Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> ATM, Optics and DIY Forum

Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | (show all)
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Hypo/Dialyte testing discovery
      #5551588 - 12/03/12 07:13 AM Attachment (127 downloads)

I posted a couple pics in Ed Turco's thread showing the small progress I've made with the Dialyte project i started months ago. Got it fairly well polished on the convex side to a smooth surface, likely well under 1/4 wave surface error.
Shown, is this objective sitting on the window sill in a cobbed stand of sorts. I set it up to use at a target bolted to the side of my barn about 35 yards away.
There are a couple things that should be noted about the pics- both pertaining to edges. If you look close, you'll see an edge issue on the -LEFT- of the lens, right at the bevel. None can be seen on the -RIGHT-. A good way to make a quick test for gross edges without any testing.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5551590 - 12/03/12 07:18 AM Attachment (93 downloads)

Obviously, this shows the edge problem is on the concave back side of the lens, which is only pad polished. The convex front has been pitch polished for a couple hours, and no such artifact can be seen on the right; nor is it in a position to be affected by the TDE of the back side. Cool, huh?

Edited by Mark Harry (12/03/12 07:32 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5551603 - 12/03/12 07:31 AM

This last pic shows the dialyte layout. With an overcorrected achro with very little power, the longitudinal color can be corrected to a large degree, and leave residual lateral color nearer the edge of the field. If an ordinary achro is used, it "becomes a Hypo" where longitudinal color also remains.
On the target on the barn, I used a piece of shelf-liner, and shot some black paint thru it onto a white background. It formed a matrix of ~1/8" dots---quick and dirty, relatively adequate for quick looks.
***
With a 40mm Plossl, i estimate the mag as somewhere near 40-50x. A bit much for what John Wall recommends, but it gave me something to look at. There was some aura around the dot matrix, but not too obtrusive considering what the optical layout was.
Now to the interesting part.
I swapped the 40mm for a 12, and the matrix exibited a rather very sensitive depiction of the longitudinal color. The dots first focused blue, with a red background in between them. As I brought it back thru focus, they darkened up somewhat, but showed a purplish aura. Even further, and the dots changed to red with a blue background.
This was extremely sensitive, and I was able to get a range from the blue dots to red dots of around 3-4mm~ (1/8"+) This effect will club you over the head! Very apparent, and very simple to do. I believe I can use it later when I get further along with development when checking the residual color issues with this design.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5551610 - 12/03/12 07:39 AM Attachment (70 downloads)

Maybe if someone has doubts about the color correction in a refractor they have, this test could be used to make a rough check. I can certainly attest it works well in this case.
Here's what I used on the back end- a 70mm short focus achro- nothing particularly special; along with an eyepiece held near the diagonal's prism.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5551611 - 12/03/12 07:41 AM

OK, Mike, you can laff your a-- off now!
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5551799 - 12/03/12 10:43 AM Attachment (65 downloads)

If I make a zero power/overcorrected achro or use a std achro with a negative flint, I should get spots something like this----
(probably a lot of you are thinking- 'he's lost his marbles!' but there's a couple good reasons for me persueing this. First one, is money- I'm tighter than a bulls behind???))
Here's a plot of the zero power achro version I have in mind:


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5551829 - 12/03/12 10:58 AM

The second thing- if a positive lens is used behind the eyepiece, after this thing passes thru focus, the positions of the red-blue is -REVERSED-; (blue focuses closer, red further out) and it can be varied with some spacing change.
This thing could be tuneable for the lateral color issue quite nicely.
Now it's rather expensive to get hold of a good quality chunk of flint for a "normal" 2 element achro of any appreciable diameter. I don't know how many times I've requested a quote and just ignored, or blown off. Crown, schmrown- I can get a whopping piece of that in 12-16" diameter, fairly readily---
SEE WHERE THIS IS GOING???
Now who the heck would refuse a look thru a refractor of sorts @ 12-16" diameter? and he could do it on the ground, too. (a boon for us old timers, etc.)
Interesting, or am I still a laffing stock (or shy a couple bricks???)
One other thing- the design I have for the zero power achro, uses only 2 radii, and a heavy, short flint that grinds and polishes astonishingly easy. I once polished FULLY a 70mm diameter piece of this stuff about a year ago in 15 -MINUTES-! (SF1)
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
glennnnnnn
sage


Reged: 10/20/09

Loc: San Diego, CA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5551839 - 12/03/12 11:05 AM

I get it! What this means is that you only need one piece of 8" diameter glass!
You might be a cheapskate, but a smart one.
Is there a specific Refractive Index that works better, or can you use any kind of glass?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: glennnnnnn]
      #5551855 - 12/03/12 11:13 AM

The piece used in the pic, is from newport; BK7 the defacto standard, and cost about as much as Supremax stuff.
I have a piece of SF1 flint that's 4.55" diameter and half inch thick that I got from Glassfab for about a C-note to be used in the correcting achro.
YOU ARE RIGHT ON THE MONEY!! Only one big piece of crown glass is necessary, which should be a cinch.
***********

I am not to be credited for the basic idea of this design. John Wall (CRAYFORDJON) was the originator of it, and I'm simply trying to carry it to a next step, as it were; with a little improvement that could make it a legitimate acceptable adaptation of a refractor of largish aperture.
Many thanks, John!
Mark


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5551869 - 12/03/12 11:21 AM

I also have to extend credit to Peter Wise. He also kicked me along to thinking about the possibilities; and to Mike Jones who thought of using a simple lens to compensate for the lateral color at the eyepiece.
Thank you both. I hope I can get this proprietary thing off the ground, so to speak.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5552290 - 12/03/12 03:37 PM


"G". only -ONE- guy sees the advantage/reason for persueing this idea??!!!
********
I don't believe it.
M.
(wt-)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5552298 - 12/03/12 03:41 PM

An advantage-
If the components can be made fairly reliably, the positions of the achro and focus are reasonably flexible. For something other than you have to spend mega-thousands on, a working example can be made expeditiously. But I think this is falling on deaf ears.
(who is the hitchin' post here???)
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mike I. Jones
Post Laureate
*****

Reged: 07/02/06

Loc: Fort Worth TX
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5552420 - 12/03/12 05:05 PM

I'm just being quiet and seeing how long you go before you start gnawing bark off trees again

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mike I. Jones]
      #5552441 - 12/03/12 05:17 PM


(GNAW!) See if santa fills your sock with coal!

M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5552545 - 12/03/12 06:25 PM

OK, I have a pile of woodchips here. I know that the big "Z" says I should make a triplet outta this stuff. But seein' that the big "Z" can't distinguish what's -REASONABLY- affordable or attainable, is there some kind of streamlining that I haven't thought of?
Maybe 1 ROC that I can use on all surfaces of the correcting achromat?
I have it worked down to 2 radii--- 80" and 16 point-something to get the plots above-----------
*******
Thank goodness for the human brain, and OSLO.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
ed_turco
Pooh-Bah
*****

Reged: 08/29/09

Loc: Lincoln, RI
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5552550 - 12/03/12 06:28 PM

I am watching...


Ed Turco


Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel
*****

Reged: 02/01/08

Re: Hypo/Dialyte testing discovery new [Re: ed_turco]
      #5552604 - 12/03/12 06:59 PM

Are you going to fold it ? Did you tell Mike that you ran a debarker at the mill ? Looks nice

Post Extras: Print Post   Remind Me!   Notify Moderator  
Lightning
sage


Reged: 07/04/10

Loc: Canberra, Australia
Re: Hypo/Dialyte testing discovery new [Re: kfrederick]
      #5552698 - 12/03/12 07:53 PM

I like it. Of course having neither a workshop or money kind of precludes taking an active role with such things but hey, please keep playing with the concept.

Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Lightning]
      #5552980 - 12/03/12 10:19 PM

I'm eagerly awaiting developments.

The inclusion of a singlet behind the eyepiece for the control of LCA is interesting; what kind of focal length is typical here?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5553242 - 12/04/12 01:53 AM

Nice design Mark.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5553514 - 12/04/12 08:13 AM Attachment (49 downloads)

I'm using a positive meniscus crown BK7, 8" diameter. It has a 40"(~) ROC convex on the front, and a concave 120" on the rear. About 3/4" thick.
*******
Hey, lightning--- so far, I've made this thing by using just a grind/polish stand, a hunk of glass, and some grits. You could likely use a good piece of plate glass instead of BK7. The achro, I think I got hold of it for about $15 US; very cheap. Probably scavenge a binocular objective somewhere. So far, that's all I have in it. I did however, spend something on the BK7 chunk. If this thing -DOES- work well, I'd just as soon have a water-clear objective to keep the detractors at bay, and the rep intact!
I'll try to include the basic OSLO file:- using the 'zero power' dedicated achro.
M.

Edited by Mark Harry (12/04/12 08:15 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5553533 - 12/04/12 08:30 AM

The file above should show the particulars of focal length, spacings, and radii. It could be folded with a flat for shortening up the finished scope.
*****
Jonesey sent me a file on a Ramsden eyepiece a while back. I have another file using a single achro from a Plossl, and one singlet, which maxed out the EDU's surface limit. Done afocally, it -APPEARS- to be correct, but I'm not 100% sure. But experiments with a std refractor, and low power eyepiece/positive singlet shows blue focusing first, or closer in across the field of view when using this singlet type eyepiece arrangement.
I sized the spotplots for both eyepiece and this scope using the same scale, and ran them thru the printer on the same sheet. Just quick and dirty, they overlapped nicely, and -should- compensate each other's lateral color problem.
As I said before, the singlet's distance from the eyepiece can adjust the degree of "compensation".
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5553546 - 12/04/12 08:37 AM

One provision:
The back side of the objective has hyperboloidal correction on it. IIRC, it's around -3.75 or so... shouldn't be a problem, similar to putting overcorrection on an 8" F.7.5: probably like correcting an F/4-4.5 which is quite achieveable. This makes the LSA's green and red-blue lines stand up nice and straight, as they should be. The delta, btw, is around .050"; quite respectable for even a std achro!
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5553616 - 12/04/12 09:24 AM

On further thought, I'm going to clean up the back side to a sphere, and perhaps experiment with a standard achro, and a piece of negative flint and see what happens. I can always aspherize the back side later if necessary. At least I can get the back side cleaned up, and reasonably accurate.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
glennnnnnn
sage


Reged: 10/20/09

Loc: San Diego, CA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5553673 - 12/04/12 10:08 AM Attachment (28 downloads)

I had that image of the large single front lens stuck in my head, because it reminded me of the Angenieux retrofocus. The difference being that the large objective is a negative lens producing a wide-angle short-focuser. Rich field when applied to a telescope?

Edited by glennnnnnn (12/04/12 10:52 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5553734 - 12/04/12 10:46 AM Attachment (39 downloads)

I have said this on another thread. I have developed the Hypo as an imaging scope, optical system comprises a 12 inch F:7 singlet OG in made from BK7, and another short focus 6 inch BK7 singlet half way along the focal length. The digital highly chromatic image was processed in the computer to produce the image shewn. I used alternate optical tricks to do this, to illustrate that there are alternate ways to skin a cat.

Post Extras: Print Post   Remind Me!   Notify Moderator  
tim53
Postmaster
*****

Reged: 12/17/04

Loc: Highland Park, CA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5553795 - 12/04/12 11:25 AM

That would be impressive if it were an RGB image.

-Tim.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: tim53]
      #5554018 - 12/04/12 01:41 PM

I smoothed the back side with a polisher slightly less than 6" diameter; which made the central 5+ inches fairly spherical, with the area out to the edge with an increasing radius, about .125" or so on the ROC. At least it's good and smooth, and a faint diffraction line is on the same side as the KE blade. Reasonable.
Placing it in the stand and setting up the achro/eyepiece end of things, It looks even better than before. A bit better contrast.
I also used the achro by itself on the target. Of course it has far less color issue, but detail was just a smidge less than with the meniscus objective. The target made this fairly straightforward to accomplish.
Lateral color (with meniscus) is still a problem- more so than the longitudinal color at present. The meniscus appeared to be distinctly brighter- not sure the exact reason; I wouldn't think it'd matter. Hmm.
Every once in a while when I have everything fairly well aligned, the small area in the central fov has very little/no lateral color.Looks nice there at low powers using 40+25mm eyepieces.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5554031 - 12/04/12 01:46 PM Attachment (31 downloads)

I did but not in the way it is normally done. I took three images in red green blue using narrow passband interference filters. Here is the green image

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5554039 - 12/04/12 01:49 PM Attachment (33 downloads)

Just for illustration, an image in white light shewing the degree of CA in the system

Post Extras: Print Post   Remind Me!   Notify Moderator  
Gary Fuchs
Pooh-Bah
*****

Reged: 05/22/06

Loc: Easton, PA, USA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5554057 - 12/04/12 02:04 PM

Quote:

There are a couple things that should be noted about the pics- both pertaining to edges. If you look close, you'll see an edge issue on the -LEFT- of the lens, right at the bevel. None can be seen on the -RIGHT-. A good way to make a quick test for gross edges without any testing.




Maybe I'm the only one that's missing the problem...could you be more specific? And what is the "quick test"?

Quote:

Obviously, this shows the edge problem is on the concave back side of the lens, which is only pad polished. The convex front has been pitch polished for a couple hours, and no such artifact can be seen on the right; nor is it in a position to be affected by the TDE of the back side. Cool, huh?




Do you mean the photo from the previous post, or the screen shot?

Quote:

Maybe if someone has doubts about the color correction in a refractor they have, this test could be used to make a rough check.




How do you mean "doubts about the color correction in a refractor"? Would your setup show something we wouldn't see just using the scope on say the moon or a bright planet?

Quote:

But I think this is falling on deaf ears.




Not at all. I enjoy reading about good new (or old) designs; especially ones I might be able to make myself; and especially if they're inexpensive.

But the designs have to be for scopes that have the potential to be really good performers and offer real advantages.
I've looked at most or all of John Wall's pictures and only a very few show even reasonable performance; and none look to be anything remotely better than what could be achieved by making a mirror out of that objective glass instead of a lens.

Is your design going to offer superior performance? Is it easier/cheaper to get a 12" or larger piece of BK7 than a suitable mirror substrate that size and the secondary, spider, and coating? And then maybe try to figure it to a hyperbola? Never mind mounting a 12"+ refractor.

I don't mean to be a wet blanket, and maybe if I understood more of the jargon I'd see the clear advantages...but so far I'm missing it.

Gary


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Gary Fuchs]
      #5554250 - 12/04/12 04:34 PM

Your first 2 quotes of mine pertain to the pic of the 8" meniscus lens. I guess you just don't see it. In a private communication with someone else recently, who is very knowledgeable about testing and paying attention to what they can see when using their eyes correctly, plainly understood full well with what I'm referring to. If you saw it for yourself instead of just the jpeg picture, perhaps you would not be 'missing it'. Or, perhaps not. It's better if you had tested quite a few pieces of glass, and looked at a lot of lenses and paid close attention to the edges. It would certainly help to have this experience.
Your 3rd quote of mine referrs to the dot matrix that's set up about 35 yards away. I related how I made it. Try it for yourself, perhaps; and with a refractor or lens to reveal what I explained.
******
Now the reply to your 4th quote, first sentence is fine. That's precisely the purpose of this scope. But I and I think others would appreciate you refraining from singling anyone out, and posting something that can be construed as criticism.
*****
There is -NO- refractor that has absolutely -NO- color. In light of that you have discounted the main competitor for reflecting scopes. But there seems to be a -LOT- of folks in the refractor forum that says they are just fine, and they spend a lot of money on them. In essence you're telling them they made the wrong decision???

" for scopes that have the potential to be really good performers and offer real advantages"

Yes, if money is no concern to you; that may be a legitimate statement. But you also said "...especially if they're inexpensive."

So which is it? You get what you pay for. The best color correction in a refractor is gonna cost you!
This is intended for low to medium powers, and hopefully bridge the gap between John's Hypo and a good achro, for a relatively modest outlay. Evolve the concept, so to speak. It might work just by making a smallish piece of PCV flint to go with a standard achro reduction lens, and to make a crown positive meniscus of full size.
And just my 2 cents, I wouldn't make a mirrored telescope with a piece of BK7 lens substrate. Can be done, but there are better choices.
Regards,
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5554288 - 12/04/12 05:05 PM

I should add a bit more...
The achro reduction lens can be obtained from S/S for something like $20 or so,(80mm F/4~; to provide longitudinal color correction) and they also have a lot of various lenses- in various precision, and even coated. Maybe more than a dozen or so, in the area of $5-15 each to be used to compensate the lateral color at the eyepiece of both the Hypo and Dialyte as referred earlier in this thread. This should satisfy the inexpensive "advantage" and also address the color issues. (pays to keep -ALL- aspects in mind that have been posted...)
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gary Fuchs
Pooh-Bah
*****

Reged: 05/22/06

Loc: Easton, PA, USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5554602 - 12/04/12 08:31 PM

Quote:

Your first 2 quotes of mine pertain to the pic of the 8" meniscus lens. I guess you just don't see it. In a private communication with someone else recently, who is very knowledgeable about testing and paying attention to what they can see when using their eyes correctly, plainly understood full well with what I'm referring to




I wouldn't call myself "very knowledgeable about testing"...but then this is an amateur telescope making forum and I'm pretty sure a number of us hope to learn here. I know I've learned plenty. Oh just for example that Texereau was wrong when he called the polishing tool we polish mirrors with a "pitch lap". ("For the past fifty years the polishing tool used almost exclusively by professionals and amateurs alike has been the pitch lap.")

I agree, I "just don't see it". That's why I asked.

Looking through a partially polished lens, through a window pane (or two?) at overexposed snow(?) on the ground at a very finite distance at what looks like a significant angle to the lens (which is supposed to be used at as close to infinity as we're likely to see) sounds to me like a questionable way to evaluate a lens. But then I'm not "very knowledgeable about testing", hence my asking. What I can see is the bottom of the window and through the lens that looks pretty straight. Same for the upright on the right side--which I understand was not in question. But what I see through the left side seems pretty ambiguous.

Quote:

If you saw it for yourself instead of just the jpeg picture




If the picture doesn't show it to an untrained eye (see above about the nature of this forum) then maybe it needs more explanation--which I don't think you provided.

Quote:

paying attention to what they can see when using their eyes correctly




Exactly why I asked for the explanation--so I can learn to use my eyes correctly and pay attention.

Quote:

Your 3rd quote of mine referrs to the dot matrix that's set up about 35 yards away. I related how I made it. Try it for yourself, perhaps; and with a refractor or lens to reveal what I explained.




Thank you. I actually read the entire thread twice, as carefully as possible for me, and the parts about the testing more. Now I see what you set up. I'll suggest using a printed sheet for an easier to make and cheaper target. Well, assuming you have a printer.

Quote:

Now the reply to your 4th quote, first sentence is fine.




Whew! Finally! Thanks!

Quote:

That's precisely the purpose of this scope. But I and I think others would appreciate you refraining from singling anyone out, and posting something that can be construed as criticism.




Understood. Will try to keep that in mind. But I think it was you that introduced someone into the thread at an earlier stage with what could be construed as if not criticism then certainly a disparaging remark:

Quote:

I am not to be credited for the basic idea of this design. John Wall (CRAYFORDJON) was the originator of it, and I'm simply trying to carry it to a next step, as it were; with a little improvement that could make it a legitimate acceptable adaptation of a refractor of largish aperture.




From my reading of many of John Wall's posts regarding his design, I got the impression--correct me if I'm wrong--that he thought the design was already an "acceptable adaptation of a refractor of largish aperture".

Quote:

There is -NO- refractor that has absolutely -NO- color.




Understood. Some can come pretty close though; and probably so close that human eyes can't detect the color.

Quote:

But there seems to be a -LOT- of folks in the refractor forum that says they are just fine, and they spend a lot of money on them. In essence you're telling them they made the wrong decision???




Oh no. Not my intention at all. I own a little refractor myself. Do any of those folks say their dialyte refractors are just fine? And if so, compared to what? Oranges?

Quote:

This is intended for low to medium powers, and hopefully bridge the gap between John's Hypo and a good achro, for a relatively modest outlay.




Would the outlay be significantly less than for a reflector of same or even smaller aperture? Because I'd rather have a fine performing 4" than a color-laden fairly sharp in the center 12" any day--costs being roughly equal.

Quote:

It might work just by making a smallish piece of PCV flint to go with a standard achro reduction lens, and to make a crown positive meniscus of full size.




May I have a show of hands for how many people here have made or feel confident in their ability to make a "crown positive meniscus of full size" versus say a decent 8" f8 mirror?

Quote:

And just my 2 cents, I wouldn't make a mirrored telescope with a piece of BK7 lens substrate. Can be done, but there are better choices.




Actually, I meant that for the cost of the BK7 an ATM ought to be able to find a "suitable mirror substrate" of a more usual glass: Pyrex, plate, whatever.

Cheers,

Gary


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Gary Fuchs]
      #5554815 - 12/04/12 11:05 PM

That's just about enough, Gary. Thank you for your contribution to this thread.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5555043 - 12/05/12 03:22 AM

May I butt in here, it is no more difficult to make a singlet lens than a mirror, the downside is that for a lens you have to make two surfaces, and you can correct it by placing a flat in front and do the usual Knife edge or rhochi test, in this case the lens will be tested at infinity focus. A red filter will give reasonable one colour light for testing. You test for a flat figure.I usually figure the back or flat surface it is easier. The upside is that lenses are very forgiving, as errors are four times less damaging than those for a mirror, that is why a lens always looks good after viewing a distant object with an eyepiece before figuring. Mirrors on the other hand have to be well figured before they even perform reasonably well, and they are very unforgiving.

Post Extras: Print Post   Remind Me!   Notify Moderator  
David PavlichAdministrator
Transmographied
*****

Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5555281 - 12/05/12 08:40 AM

This is a good thread. Let's leave the snark at the door, please.

David


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: David Pavlich]
      #5555413 - 12/05/12 10:20 AM

Er sorry I wasnt aware I was snarking, only giving advice.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5555889 - 12/05/12 03:50 PM

I have a plaster tool curing for the F2 flint that will go with the reducing achro. Might be a few days before I report anything more. I anticipate it will have to be switched to a short, or heavy high index flint before done. John, I wouldn't worry!
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dave O
sage
*****

Reged: 12/21/11

Loc: Sri Lanka
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5556677 - 12/05/12 11:41 PM

Hey Mark -- I enjoy and follow threads such as this one and several by John as I find the 'Hypo' design both innovative and interesting. Obviously building a 'largish' refractor using only one large piece of glass, which is easily obtained is something worth pursuing.

I do wonder though, what advantages the 'hypo' has over say a Shupmann?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Dave O]
      #5556794 - 12/06/12 01:58 AM

That is why I started researching Dialytes and of course the the non dialyte Hypo recently. The lure of large refractors is a heady one. forbidden fruit and all that.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Lightning
sage


Reged: 07/04/10

Loc: Canberra, Australia
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5556945 - 12/06/12 06:35 AM

Let's not forget that people are having *fun*! Mark and John are excited about this stuff and that in itself is great to see.

Besides, an array of these suckers would be an awesome narrowband survey/deep-sky photography tool.

Nice rich-field scope too...

I've almost cleared the garage and will be getting my wood-working tools prior to Christmas.

I think it'll be playtime for me in the New Year.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Lightning]
      #5556987 - 12/06/12 07:37 AM

I should probably clarify the differences between the Hypo and the Dialyte that are covered here. John's version can be made expeditiously with nothing more than surplus optics- a 6" lens, and achro(s) from S/S.
Mine is a bit different and more involved. You may want to have a good mirror or two under your belt in order to fabricate what the Dialyte requires.
The ultimate version of what I'm making requires a positive meniscus, a 'zero power' achro overcorrected for longitudinal color,(made with a heavy but readily obtainable smaller flint) a very low power eyepiece or possibly just an achro, to be used with a positive crown lens either in front of, or behind the eyepiece to get rid of lateral color. (some experimentation is required)
This Dialyte -should- work as good as any standard achro; or at least fairly close. I would estimate it could reach somewhere around 25-50x/inch. I could build it for a fraction of what a standard achro would be (I hope!) since only 1 piece of large glass is needed.
This differs from John's scope. His, if I recall, doesn't solve issues with color, but minimizes them; and by restricting the useage to around 15-30x, if I recall correctly. The Dialyte should bridge the gap between the std achro, and his scope. It should keep glass cost manageable, at least better than an achro. It differs from an achro; in that instead of correcting the color issues at the 2 main lenses all at once, it does so by solving first longitudinal first- and then for lateral at the eyepiece.
****
My 'swag' at this point- I think the Dialyte should give any achro of accepted good quality a run for the money. Everything at this point is proprietary; an exploration.
I have Daley's book. I've read it a few times Nice scope, though it seems to be characteristically a narrow field instrument. I sort of like to have a more wide field capability. I also have a lot of lensmaking under my belt, so have no real issues making what I might need for this project, which doesn't require anything to be coated, etc. Just polish, and try it out; which could be handy with tweaking. Another aspect, alignment. Nothing special, rather easy and straightforward. Spacings are also very liberal tolerance wise, and iterations are rather easily handled- though I wish OSLO would come with an extra surface or two. The Schupmann- a bit more involved???

And as Lightning says- it's fun! I'm an incurable glasspusher, so it gives me an interesting project that occupies my time during winter months.
Wouldn't it be something if it works as planned??!!
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gary Fuchs
Pooh-Bah
*****

Reged: 05/22/06

Loc: Easton, PA, USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5557136 - 12/06/12 09:31 AM

Quote:

a 'zero power' achro overcorrected for longitudinal color




Would you explain what tools/techniques (if any) would be needed, beyond those typically used for amateur mirror making, to make and test that lens?

Thanks,

Gary


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Hypo/Dialyte testing discovery new [Re: Gary Fuchs]
      #5557242 - 12/06/12 10:37 AM

Mark,
You may want to look up an article by Roland Christen in Tescope Making. I believe the title is 'Super Planetary Objectives.' and I think was in TM28. As anyone who has designed an achromat knows, the color correction is determined by the refractive index of the glasses. The curves correct for spherical and coma but there is no magic set of curves that results in perfect achromatic performance. Again, it is the refractive index of the glass that is what counts. Christen found an article in Applied Optics from the early 1960's were it was shown that if you draw a straight line on a graph of partial dispersions of optical glass, any three glasses that fell on the line would result in APO correction. To make fabrication of a triplet easier he wanted R2=R3 and R4=R5 and wrote a computer program to search all the combination of three glasses that fell on the straight line on the curve were the inner radii pair were the same that would result in APO type color correction.
The same would be true of a dialyte. So if you made the singlet from inexpensive glass then there should be two other glasses that could result in APO type color correction. Since the secondary lens is small, one could use more expensive glass. This agian is what Christen did when he design a triplet color corrector for a typical achromat. Because the color correction was fixed by the achromat he was forced to use a very expensive piece of glass but since you have freedom to start with, much less expensive glass could be used.
Mark, I'm sure you seen this reference but for anyone else that wants to understand what the problems are with the Dialyte design and some attempts to fix them here is a link that explains them http://rohr.aiax.de/Chapter%205.htm

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Gary Fuchs]
      #5557278 - 12/06/12 10:55 AM

Mark definately has something here. This is what I urged people like Mark to do with the simple very basic idea of the Hypo, IE develop it! and he has done just that. The Dialyte is a badly neglected instrument, and it has enormous potential for the development of high aperture refractors. Peter Wise has developed a high end apo from the retro focal dialyte system, the scope however is not for the timid as really precise optics spacings and centering is a must for this scope, Peter's apo also has one fluoro glass lens in the system, but only 30mm dia, however the scope is an eight 8 inch, you dont get that economy with a current state of the art triplet.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Dave O
sage
*****

Reged: 12/21/11

Loc: Sri Lanka
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5557378 - 12/06/12 11:52 AM

Quote:

<snip>
Wouldn't it be something if it works as planned??!!
M.




OK! Now the light clicked on for me and I have a better understanding of what you are trying to do. Good luck, and keep us posted! Cheers. Dave O


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gary Fuchs
Pooh-Bah
*****

Reged: 05/22/06

Loc: Easton, PA, USA
Re: Hypo/Dialyte testing discovery new [Re: Dave O]
      #5557653 - 12/06/12 02:35 PM

Quote:

Everything at this point is proprietary




Sorry, I need to read more carefully before asking questions. I kind of skimmed over that part inadvertently. Maybe will start a new thread and ask others how to make that sort of lens and do the testing.

Gary


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Gary Fuchs]
      #5558349 - 12/06/12 09:52 PM

Proprietary? Mayhaps the word intended was 'preliminary'?

Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: DAVIDG]
      #5558372 - 12/06/12 10:12 PM

DAVIDG, personally if I decided to make a dialyte I'g do with a Mangin mirror rather than an achromatic lens corrector. Using three single elements, all of the same (cheap) BK-7 variety, you can achieve full apochromatic color correction, no lateral color to speak of, flat field, fully anastigmatic performance at just about any focal ratio (from f.3.5 and slower), large field size, closed tube, no aspherics, and the whole telescope mounted on a low gravity, stable mount.

Rohr's refractor-type solutions just seem like needlessly expensive exercises in futility. In fact, he removed his home page because the designs are outdated!

Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5558659 - 12/07/12 03:34 AM

Sticking to Schupmanns is OK but this special case dialyte is a Catadioptric refractor and has severe limitations inherent in the optical design. Petzval type and retrofocal type dialytes are open to almost infinate adaptation and evolution, that is why the technology is so fascinating. If it is considered an exersize in futility then those who do so are lacking imagination and the inventive spirit that pushes human knowlege forward. In Science we have two kinds of scientists, those who say " it cant be done" and the other kind who see that an idea might have great potential even if it proves to be a dead end in the long run. I am the second kind.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5558849 - 12/07/12 08:51 AM

Yes, pardon the error!
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel
*****

Reged: 02/01/08

Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5558864 - 12/07/12 09:05 AM

John you are my kind of ATM not afraid to try something unproven .Some new way of doing things .So glad you share on here .

Post Extras: Print Post   Remind Me!   Notify Moderator  
Gary Fuchs
Pooh-Bah
*****

Reged: 05/22/06

Loc: Easton, PA, USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5558954 - 12/07/12 10:06 AM

Quote:

Yes, pardon the error!
M.




Maybe just a Freudian slip? So then I don't have to retract my question about tools and techniques for making that lens...

Gary


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5559007 - 12/07/12 10:29 AM Attachment (21 downloads)

Crayfordjohn, I believe I said "if I decided to make a dialyte..." not "if I decided to experiment with a dead-end design". If you have two known solutions and one gives perfect images while the other doesn't, then choosing the latter is an exercise in futility, imo.

If you have new techologies then further investigation is in order, but reinventing the wheel is and always will be an exercise in futility.

For those who are not familiar with the Manigin dialyte systems, here is one Mike I. Jones designed and posted on CN some time ago of a 5.5 inch f/7.4 system. The spectral range, in case you wondered, is from 400 to 900 nm! The field is 1.4 degrees (1 inch) in diameter. Try that with Rohr's configurations.

Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5559036 - 12/07/12 10:49 AM

Quote:

DAVIDG, personally if I decided to make a dialyte I'g do with a Mangin mirror rather than an achromatic lens corrector. Using three single elements, all of the same (cheap) BK-7 variety, you can achieve full apochromatic color correction, no lateral color to speak of, flat field, fully anastigmatic performance at just about any focal ratio (from f.3.5 and slower), large field size, closed tube, no aspherics, and the whole telescope mounted on a low gravity, stable mount.

Rohr's refractor-type solutions just seem like needlessly expensive exercises in futility. In fact, he removed his home page because the designs are outdated!

Mladen




Mladen,
Exactly! That is why I build Schupmanns. By the way, those are not "Rohr configurations" but a discussion by Roger Ceragioli about different refractor designs and the link I provided was a paper that Roger had posted. The material was expanded upon and became part of his new book and excellent book on optics "Telescope, Eyepieces and Astrographs".

All the Best and Happy Holidays,
- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel
*****

Reged: 02/01/08

Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5559052 - 12/07/12 10:56 AM

Yours has a large obstruction and is a reflective system . All is not yet known . I know only good thing come from smart people trying new things .When they fail sometimes that is when most is learned .Nothing like having the real telescope to learn from . Obstruction effects are real but we are use to seeing it in the images . Having a design in OSLO is not like having the real telescope . Mark and John knows what he is doing we should relax we might all learn some.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mike I. Jones
Post Laureate
*****

Reged: 07/02/06

Loc: Fort Worth TX
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5559061 - 12/07/12 10:59 AM

Thanks for resurrecting that one, Mladen. I need to ping Dane and see if he ever built it. Shoulda been/will be a sweet scope.
Mike


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: kfrederick]
      #5559063 - 12/07/12 11:01 AM

Thanks DAVIDG. Happy Holidays to you too.

Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dave O
sage
*****

Reged: 12/21/11

Loc: Sri Lanka
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5559092 - 12/07/12 11:16 AM

Mladen -- looks to be a variation of the Busack/Honders -- a very elegant design to be sure ... however ... it IS obstructed. For many, a central obstruction is noticeable, particularly as a loss of contrast, which is one reason refractors are still very popular in spite of their high cost; as well as many ATMs venturing (with great success I might add) into the tilted mirror telescope designs.

I think this particular design has potential; but unless folks are willing to experiment (play?) with them, that potential may never be realized. The Busack/Honders came about around 2000 or so ... only three elements, all spherical surfaces, common glass and you get as perfect an image as you could ever hope for (in an obstructed system) ... what took so long? There are still things that have not been 'discovered' and only by looking will we ever find them.


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: kfrederick]
      #5559113 - 12/07/12 11:27 AM

Quote:

Yours has a large obstruction and is a reflective system . All is not yet known . I know only good thing come from smart people trying new things .When they fail sometimes that is when most is learned .Nothing like having the real telescope to learn from . Obstruction effects are real but we are use to seeing it in the images . Having a design in OSLO is not like having the real telescope . Mark and John knows what he is doing we should relax we might all learn some.



You're right kfredrick, the CO is 1/3 the CA but that's because Mike I. Jones designed it for Dane as an astrograph with a huge field at that focal ratio. If you wanted smaller field you'd have much smaller central obstruction without serious diffraction effects.

I used Mike's configuration as an example of Mangin dialytes are capable of (mind you, at f/7.4 not f/15!), compared to dialyte refractors. The Mangin dialiyte is a true apochromat over a hughe spectral range, and a true flat-field anstigmat (no spherical aberration, coma or astigmatism to speak of) - and this is all possible with the cheapest glass (BK7, for all three elements. No exotic, expensive glasses needed!

As they say, it's hard to argue with success.

Obviously if I had to choose a dialyte I would go for a Mangin catadioptric system. If I wanted to experiement with different configurations, then all options are open. However, pursuing the ones already tried and retired seems to me somewhat pointless. That's all.

Reagrds,
Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Dave O]
      #5559117 - 12/07/12 11:30 AM

In spite of all that, the retro has no central obstruction or a tilted mirror, it has been perfected by Peter Wise and is an APO, it is cheaper than most with a very high performance, I stick to my guns on this and will always look for news ways to do things, no matter if certain dsigns are the "last word", they are not.

Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: Mike I. Jones]
      #5559132 - 12/07/12 11:38 AM

Quote:

Thanks for resurrecting that one, Mladen. I need to ping Dane and see if he ever built it. Shoulda been/will be a sweet scope.
Mike



Hi Mike, yes that was a definite keeper. Thanks. I am also curious if Dane gave it a try. If I remember the discussion of these, the clincher is the Mangin mirror which is in effect a Maksutov-like meniscus with all the thickness, and radius of curvature spot-on requirements that come with it. Also, the back surface of the Mangin has to be a super smooth, zone-free surface of reflector quality. Being convex, it would require advanced techniques and tooling to achieve.

So, I can understand why then a dialiyte refractor may be more attractive for novices, but there is no question which is a better optical system.

regards,
Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: Dave O]
      #5559163 - 12/07/12 11:55 AM

Hello Dave O. The central osbtruction in this case is large (but not too large) because the system is an f/7.4 and designed to cover a large field. If you were to make it an f/10 then the CO will be smaller as well. As long as you can keep the CO about 20-25% of the CA the diffraciton effects are not too injurious.

I understand the fascination with unobstructed telescope, but, what's the point of having a slower, longer, more cumbersome system with no central obstruction and obvious uncorrected chromatic halo around bright images?

If I had to choose an unobstructed system and perfect color correction I would go with a Schiefspiegler, not a dialiyte refractor. Why bother with lenses?

However, let me be clear about something. It looks like some have misread intentions in what I wrote that are not there, so I want to stop it before it continues in that direction: There is nothing whatsoever that I wrote to DAVIDG that should be construed as criticism of experiments, or resistance to research in general. I simply stated that "if I had to choose a dialyte..." then I wouldn't waste my time with known/existing designs of inferior quality. Nothing else should be read into that statement. Thank you.

regards,
Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5559167 - 12/07/12 11:57 AM

Quote:

In spite of all that, the retro has no central obstruction or a tilted mirror, it has been perfected by Peter Wise and is an APO, it is cheaper than most with a very high performance



Do you have his design to share?

Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Jones
Carpal Tunnel
*****

Reged: 04/06/04

Loc: Sin-sin-atti
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5559828 - 12/07/12 07:03 PM Attachment (38 downloads)

Mladen,
The Jones-Medial is a refractor that has no obstruction, color, coma, field tilt and uses 3 pieces of common glass. I am at the assembly/testing stage on mine although I haven't had much time to work on it the last few months.


Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel
*****

Reged: 02/01/08

Re: Hypo/Dialyte testing discovery new [Re: Ed Jones]
      #5559850 - 12/07/12 07:30 PM Attachment (28 downloads)

Nice design ED If I was building it I would try my interlocking box with slots for the plates to hold the optics like I used on the CHief

Post Extras: Print Post   Remind Me!   Notify Moderator  
jgraham
Postmaster
*****

Reged: 12/02/04

Loc: Miami Valley Astronomical Soci...
Re: Hypo/Dialyte testing discovery new [Re: kfrederick]
      #5559931 - 12/07/12 08:32 PM

Very, very cool Ed. I'm looking forward to your reports on this one.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Dave O
sage
*****

Reged: 12/21/11

Loc: Sri Lanka
Re: Hypo/Dialyte testing discovery new [Re: Ed Jones]
      #5560099 - 12/07/12 10:44 PM

Wow Ed! You lost the obstruction and it didn't even cost more glass! Looks to be a dandy!

Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: Ed Jones]
      #5560197 - 12/08/12 12:02 AM Attachment (25 downloads)

Quote:

Mladen,
The Jones-Medial is a refractor that has no obstruction, color, coma, field tilt and uses 3 pieces of common glass. I am at the assembly/testing stage on mine although I haven't had much time to work on it the last few months.



That's the way to go Ed! Beautiful images. The Manign dilaytes are a proven design for fully corrected apochromatic configurations, in Newtonian, off-axis and Cassegrain modes. And no exotic glasses needed! Very impressive.

I would be curious if you could share with us the problems and challenges producing the Mangin mirror.

BTW, here is another Mike I. Jones original - a Cassegrain dialyte solution he and I talked about a while back: all spherical surfaces, fully apochroamtic and anastigmatic performance, simple N-BK7 glass.

Imagine, instead of a cumbersome Schmidt corrector plate, the front corrector is just a simple plano-convex lens! Think how much cheaper would it be to make catadioptric Cassegrainss this way. It brings such configurations into the ATM realm. This one doesn't even require a field lens! (the secondary is also a Mangin mirror)

This 8-inch f/20 design would make a fantastic, compact planetary scope to die for and perfectly executable by advanced amateurs!

Mladen

Edited by MKV (12/08/12 09:52 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5560330 - 12/08/12 02:00 AM

Another Schupmann yet.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5560381 - 12/08/12 03:16 AM

Mark, does the Ed Jones Medial really belong on this thread? It is not a really a new idea in optical thinking, it is definately not an "outside the box" conception, which your design is! we have regressed into a mere recycling of the same old tired designs.

Post Extras: Print Post   Remind Me!   Notify Moderator  
nytecam
Postmaster


Reged: 08/20/05

Loc: London UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5560394 - 12/08/12 03:59 AM

Quote:

Another Schupmann yet.


Hi John - Mark Harry's thread been highjacked - why do I get the strong impression some experts don't like your design - again
Of course anyone can reintroduce the original thread right here -right? [I love the 'right?' americanism]


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: nytecam]
      #5560471 - 12/08/12 07:32 AM

I'm just sitting back eating popcorn, or sipping a cup of Joe. (and tinkering away...)
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mike I. Jones
Post Laureate
*****

Reged: 07/02/06

Loc: Fort Worth TX
Re: Hypo/Dialyte testing discovery *DELETED* new [Re: Mark Harry]
      #5560519 - 12/08/12 08:35 AM

Post deleted by Mike I. Jones

Post Extras: Print Post   Remind Me!   Notify Moderator  
Aljr
member


Reged: 12/08/10

Loc: BRAZIL
Re: Hypo/Dialyte testing discovery new [Re: Mike I. Jones]
      #5560836 - 12/08/12 12:45 PM

That sounds great to me!!! , but John Wall (re)open the door. Ps.:I am the 50° fifth recreational design:

Quote:

And by "Joe" he means C2H5O

I am 100% behind exploratory, recreational optical design. It's how I stirred the pot and came up with the designs that Mladen brought up here. Ed Jones and Mark Harry are also recreational explorers, as is Peter Wise and 50-odd other names I could drop. I guess that's why I am offended by the term "tired old designs" above. I could say that this "hypo" thing is also just a recycling of "tired old designs", in this case a Petzval lens, albeit with uncorrected Petval field curvature and lateral color. That's the only "AHA I get it!!" moment I get from a "Hypo". But knowing that doesn't trivialize it or render it undesirable to try building - it's a simple way to achieve a large-aperture refractor while only needing to make but one full-aperture refractive element. That's all Mark has presented this to you as, and I'm looking forward to his First Light report. But can we also respect and welcome other designs as well, and not practice what is effectively optical design racism?
Mike




Edited by Aljr (12/08/12 12:49 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Aljr]
      #5560940 - 12/08/12 02:03 PM

I am afraid that the term "tired old design" has been appended to the Hypochromat, well of course this shews very clearly that once more my thesis has been briefly scanned and all the wrong conclusions perceived, good old knee jerk reaction as usual. Now if you read my thesis carefully and take in all the points laid down you will get a different perspective of what I am trying to say, and with a bit of luck it will be the right one just for once. The term tired old sesign in the case of the Hypo shews I am right here in saying this. So let me remind you once more, the Hypo was discovered by me four years ago when I noticed an anomaly in the image quality which just should not have been there while I was analyzing a retro lens set on the optical bench in my lab. I realised that this would produce a very simple, if imperfect refractor. I noticed subsequently that this anomaly does not appear in any of the optical text books, so I assumed that it was a new discovery. I have repeatedly explained the simple principles of the Hypo on this forum with basic geometrical optical diagrams, and yet the message did not and still has not gone across. There are a small few who took the trouble to understand what I was saying and they understood, but just a very few. Mark is one those few. and Aldevio in Brazil took the design on board with great enthusiasm, and he has now built and researched several versions of his own. I just mention these two. It seems to me that on the ATM forum most have entrenched ideas based on those designs that have been with us since the German physicists made all those discoveries back in the 19th century, and of course you cannot discover any more, because it has all been done and dusted, a prejudice cast in tungsten carbide. The old reaction to Marks research is that it has all been done before by Petzval, the fact that Mark has come up with an achromatic version of a Hypo does not seem to get across. Even the Hypo has been described as a Petzval deriviative, which it definately is not as it bears only a vague morphological resemblence and no more. When I joined CNR ATM forum I was nticipating lively and imformed discusions abouit new ideas, but so far in all thast time, only a very small handful have done this, 99% of the time it has been carping destructive critisism all the way.

Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Hypo/Dialyte testing discovery new [Re: Aljr]
      #5560954 - 12/08/12 02:13 PM

I think the push back might be that the spot diagrams are not very good. Experimentation is great when you don't know the out come or your testing a theory. It is what I do for a living. In this case the spot diagram is clearly predicting the out come and the theory behind the raytracing math is solid. One stirs the pot around here when a design is posted that shows excellent results via raytracing. In this thread alone there have been a number of new designs discussed. Why have they been built or being built? Because the spot diagram showed the excellent results that could be achieved.
- Dave

PS Mark might want add a splash of hydrogen to that C2H5O 'Joe' to flavor it up so it more like CH3-CH2-OH. That additional 'H' makes a big difference in the taste, trust me !


Post Extras: Print Post   Remind Me!   Notify Moderator  
Aljr
member


Reged: 12/08/10

Loc: BRAZIL
Re: Hypo/Dialyte testing discovery new [Re: DAVIDG]
      #5560995 - 12/08/12 02:42 PM

All humans now know that the earth is round / spherical, but many humans can not do an experiment to prove. And many researchers believe in the "perfect theory". the "perfect theory" explains everything. I disagree.
If there were a "perfect theory", missions to Mars should be canceled. If there were "perfect theory", would not have discovered a huge oil reserve here on the coast of Brazil.


Post Extras: Print Post   Remind Me!   Notify Moderator  
DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: Hypo/Dialyte testing discovery new [Re: Aljr]
      #5561093 - 12/08/12 03:44 PM

What new theory are you trying to prove with a Hypo Dialyte ? The math discriping the interaction of light with refractive and reflective surfaces has been well established and tested many times. So unless there is a bug in the software of both OSLO, Zemax or any other raytracing program, they predict the results extremely well of any optical design that uses these materials. There are millions of designs to prove this. So why should one throw all that data away and experiment with a design that using these proven tools that shows it not to have very good performance ?

- Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gary Fuchs
Pooh-Bah
*****

Reged: 05/22/06

Loc: Easton, PA, USA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5561140 - 12/08/12 04:18 PM

I used to see a lot of newcomer's questions here and elsewhere replied to with "Search the archives, this has been answered before." Lately I think folks are starting to realize that while the answers might be in the archives there's so much there that a search can take a long time unless you know the subject well enough to structure a very specific search phrase--which of course being a newcomer you don't know how to do.

When something is posted here that piques my interest--like the current thread--I want to learn about it because maybe there's some improvement I can make in what I'm doing. Who knows, I might even be able to offer a suggestion.

Now I know of a couple of ways to make and test a convex surface...but one thing that got me interested in this thread was the idea that there might be other easier ways--ways that might not have been either known about or described before, either online or in various books--which might be known to a person with particular professional optical fabrication experience.

The answers to my questions were, with one minor exception, not forthcoming. This isn't the first time the OP has either not described a technique, or given a partial explanation, or just tantalizing glimpses.

This is an amateur forum. Not, at least for the participants as far as I know, a place to self-promote. If you're going to talk about a design or technique then you should be prepared to answer reasonable questions--questions like how do you make and test the glass you're describing as relatively easy to make and test.

If the techniques you're using aren't proprietary and are well known and you don't feel inclined or have the knack to explain what's been said well elsewhere then go ahead and cite references that any of us can lay our hands on.

Now, as far as the Wall Hypo is concerned, there were a lot of pictures posted but almost all were of fairly poor quality and not of astronomical targets and many had obviously been post-processed. So what they show is questionable. To my eye about what you might expect from a cheap pair of binoculars. There was nothing compelling to induce me to build one or even to place any faith in the claims.

Now if it were actually harder to make say a 12-16" mirror for a Newtonian then a refractor that size would be more appealing as an alternative.

It sounded to me like the OP's design had color issues with two of the extra lenses along two axes. If the alignment procedure is easy for that I'd like to have it described--and not just as being easy and simple for anyone who's made two good mirrors.

And hijacking threads...well, there are tangents and then hijacking. Not always easy to say when what occurs but certainly not hard to just say. Before we call any kettles black it might be good to consider history.

I'm all ears for those explanations of tools and techniques. I'm working on a convex surface right now and if there's an easier/simpler/cheaper way to do it than making a test plate and interference testing against that I'd love to hear it.

And if I can easily make a big loose tolerance objective and add some cheap loose tolerance OTS lenses and with a simple alignment technique end up with a 50X/inch color-free refractor with great contrast...wow, count me in as soon as I can lay my hands on that big glass...but, if it's going to end up for sale with crucial specs either secret or patented then go ahead and make it and pay for advertising like any other business...

(Incidentally, we've heard enthusiastic things before; and that attitude is fine...but attitude alone doesn't make something work.
If I were to get the idea that gasoline might make a new kind of very effective fire extinguisher material and head over to the Fire Extinguisher Forum and talk about what a great new idea I had--after all, there's nothing like this in the literature or patented and since water and gasoline are liquids and one ought to work as well as the other--should I expect all sorts of acclaim and support and lively discussion of the relative possible merits of one octane over another or the value of varying amounts of ethanol? Should my feelings be hurt because people point out the obvious? At the very least, if I have in mind to do something special and new with the gasoline to make it better at putting out fires than say water then shouldn't I describe it? Peer review?)

Gary


Post Extras: Print Post   Remind Me!   Notify Moderator  
Aljr
member


Reged: 12/08/10

Loc: BRAZIL
Re: Hypo/Dialyte testing discovery new [Re: DAVIDG]
      #5561310 - 12/08/12 06:31 PM Attachment (28 downloads)

Quote:

What new theory are you trying to prove with a Hypo Dialyte ? The math discriping the interaction of light with refractive and reflective surfaces has been well established and tested many times. So unless there is a bug in the software of both OSLO, Zemax or any other raytracing program, they predict the results extremely well of any optical design that uses these materials. There are millions of designs to prove this. So why should one throw all that data away and experiment with a design that using these proven tools that shows it not to have very good performance ?

- Dave




Maybe John Wall can never agree with what I say:
The person who will find the bug / get the credit.
The programmer who wrote the program(Oslo, Zemax, DBoptic) might help. Maybe some student who wants to defend his doctoral thesis. John measured the results on your countertop and the program gives another result. In my simulations with DBOptic, I noticed that when we insert in the program DBoptic, a series of lenses to form an equivalent lens(this is similar to a combination of resistors) the program provides a result that agrees / is similar to experiment / practice. I would like to apologize to John Wall for doing your Hypo with a OG lens F/D 17, he recommends f/d 30 or f/d 40. HE NEVER ACCEPTED IT. I then decided to put a series of negative meniscus (common spectacle lens), in front of the OG lens, in order to extend the focal length of the lens at F / D 40. In my mind, every time I put a negative meniscus of -0.25 diopters in front OG lens, the focus of the OG lens would be far / long, so focus lens OG could also be infinite... Anyone can try this in the program. Take a OG lens 150/3000mm, place 8 meniscus of -0.25 diopters, 1700mm after OG lens front, and an achromatic doublet 70/500mm behind( +/- 50mm distance after meniscus). See soluction.jpg and bug.jpg


Post Extras: Print Post   Remind Me!   Notify Moderator  
Aljr
member


Reged: 12/08/10

Loc: BRAZIL
Re: Hypo/Dialyte testing discovery new [Re: Aljr]
      #5561313 - 12/08/12 06:34 PM Attachment (31 downloads)

The Bug, this system is Better(only one negative CR39 meniscus lens -2 diopters = -0.25x8). Good Results in practical. See bug.jpg

Edited by Aljr (12/08/12 07:35 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: Aljr]
      #5561505 - 12/08/12 09:05 PM

Excsue me, Aljr, how can you have three air spaced elements and only 5 surfaces??? Thanks.

Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
Aljr
member


Reged: 12/08/10

Loc: BRAZIL
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5561561 - 12/08/12 09:50 PM Attachment (19 downloads)

Surfaces are 7 in total. Is understood: there are three elements. Please, see this new drawing: I went down the "scroll bar" on DBoptics.

By other hand: is important I say: the sketches above are referring to dialyte Petzval. These drawings do not refer to Hypo.


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: Aljr]
      #5561599 - 12/08/12 10:20 PM

Quote:

Surfaces are 7 in total. Is understood: there are three elements. Please, see this new drawing: I went down the "scroll bar" on DBoptics.

By other hand: is important I say: the sketches above are referring to dialyte Petzval. These drawings do not refer to Hypo.



Thank you, sir, for clarifying this.

Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: Aljr]
      #5561615 - 12/08/12 10:36 PM

Aljr, are you saying this configuration is corrected?

Regards,
Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5561849 - 12/09/12 03:45 AM

Yerse Mike, point taken. The snipe at " shewn" is of course how we spikka da lingo ere in good old Blighty. As to the bad images taken with a hypo, you are right, they are bad, but I have already admitted that, the quality is mainly due to the fact that I am not using an imaging camera, but an ordinary bog standard camera such as a Panasonic Lumix, great for the snap shot general public but not too good on critical focus, next the shots are also taken through double glazing, which dont help much, however the images are to illustrate the lack of " huge amounts of colour" that have been levelled at the system, which of course is untrue, if it were so, I would have abanded the Hypo at birth, and none of you would have heard about it. Now I come to the nub here, you have still not grasped the points I laid down in my original thesis, so I will go over them once more. The Hypo is a visual instrument. The hypo only works at low power as found in binoculars etc, so it belongs in that region of use. The Hypo is incredibly cheap to build. The Hypo can be made by those starting out in ATM or Astronomy. The Hypo when used visually gives bright and very clean images. The Hypo has colour in the system, but it is of a low order and is tolerable to ordinary folk. The Hypo is not the new scope that will sweep the board. Now Mike, it is a matter of choice, as you sniffilly aver that you will never bother to make one, so be it, I am not bovvered one bit, its your choice. Finally we come to my egotistic attitude, sorry about that and you have a right to say so, but in my defence my attitude is due to the obdurate refusal to entertain my point of view, not accept it mind you, and so far the whole idea of the Hypo has been met with derision and hostilty, by the majority of the ATM population here, which says something! believe you me. I will say no more on this topic.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5561898 - 12/09/12 05:43 AM

This thread has totally fallen thru the floor; nowhere near on topic of an interesting facet of a test I made on longitudinal color. That was totally ignored.
Otherwise fine and good minds here have allowed themselves to be drawn into endless bickering, nitpicking, pontifying, and posturing.
******
It's sometimes a wonder (to myself) -WHY- I even bother to try posting about something interesting that I may have observed, come across, or might be working on....
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel
*****

Reged: 02/01/08

Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5562014 - 12/09/12 08:46 AM

Mark there are many who read and get informed from your posts. Think you could use two eyepieces with one lens if the large singlet was slow enough .

Post Extras: Print Post   Remind Me!   Notify Moderator  
ed_turco
Pooh-Bah
*****

Reged: 08/29/09

Loc: Lincoln, RI
Re: Hypo/Dialyte testing discovery new [Re: kfrederick]
      #5562230 - 12/09/12 11:18 AM

Mark,

Please please, keep up the posts. Nitpicking sometimes help discover something better.

As to those pictures shown; they were taken through Double Glazing I can only imagine what these systems work outside! Open that window forget the seeing and the heat loss and look through air only. It may be lousy but a lot better than glazing and/or a window screen; (mine has both).

Maybe on a warmer day; but please, take new piccys.

Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: ed_turco]
      #5562908 - 12/09/12 06:25 PM

They ain't my pictures!
Actually using this meniscus like a hypo can resolve small overspray specs down to .005-.010" in diameter at about 35 yards- window open, or closed.
It impresses me at the moment that without any baffling that the extraneous light is spoiling the MTF to a degree.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
jgraham
Postmaster
*****

Reged: 12/02/04

Loc: Miami Valley Astronomical Soci...
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5563292 - 12/09/12 10:51 PM

Despite the lively banter, I've seen nothing in this discussion that would stop anyone from pursuing this design if they wanted.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: jgraham]
      #5563570 - 12/10/12 04:59 AM Attachment (23 downloads)

Ed. Here are a couple of test pics outside using a six inch standard Hypo. The greenish cast is Cyan, as the 50mm Plossl is coated with "Ruby" coating. Minus red from RBG gives Cyan. Yes it is about time this thread was put back on the rails so here is the kick off.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563571 - 12/10/12 05:00 AM Attachment (18 downloads)

Same greyscale

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563572 - 12/10/12 05:03 AM

Any slight fuzz is due to the quality of the Camera, which is cheap and cheerful.

Post Extras: Print Post   Remind Me!   Notify Moderator  
ed_turco
Pooh-Bah
*****

Reged: 08/29/09

Loc: Lincoln, RI
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563748 - 12/10/12 08:50 AM

Your pics are most informative. Why not go for a full color shot? Pretty please?


Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: ed_turco]
      #5563924 - 12/10/12 10:48 AM

The green imageis a full colour shot, the other is greyscale.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563934 - 12/10/12 10:55 AM Attachment (16 downloads)

To follow on I have been developing a Hypo style refractor which had no achromatic elements in it at all, the idea behind the concept is to get three monochromatic images: R G B, and then combine them into a colour image free of CA and LCA. Three interference filters were used. The last image is the green one greyscaled.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563939 - 12/10/12 10:57 AM Attachment (12 downloads)

The three separate images. First

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563941 - 12/10/12 10:58 AM Attachment (19 downloads)

Second

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563946 - 12/10/12 11:00 AM Attachment (17 downloads)

Third

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563947 - 12/10/12 11:01 AM Attachment (21 downloads)

Forth

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563959 - 12/10/12 11:07 AM

Just taking one image in green will yield a good image when greyscaled. OK for the Moon, for instance, The system being monochromatic is not constrained by the low power initiative, and very high powers can be used.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5563985 - 12/10/12 11:26 AM Attachment (22 downloads)

Ed here is a full colour image taken wuth a six inch Hypo, a bit unsharp, but the camera is not up to it.

Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5564062 - 12/10/12 12:17 PM

What is the focal length and aperture if the camea's taking lens? If a small-format point and shoot, the aperture (for daylight exposures, and when not zoomed in much) might be as small as about 1mm. This will effectively stop down the telescope if the exit pupil is larger.

For example, an 8mm f.l. lens at f/8 would have its aperture stopped down to 1mm. If the scope's exit pupil were to be, say, 6mm, that 150mm aperture would be effectively reduced to 1/6, or a mere 25mm. This will offer dramatic improvements in aberrations.

This is one of the dangers of afocal imaging. And I contend that the camera is well up to the task of representing what it 'sees', as long as it's reasonably well centered and positioned, and not shaking during the exposure. If the camera is so bad, all other 'normal' snaps would be poor, too.


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5564184 - 12/10/12 01:21 PM

Quote:

Forth



So, you have to adjust the size as well? Nice photo art.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5565765 - 12/11/12 11:27 AM Attachment (24 downloads)

I switched to internal imaging techniques by fitting a 5 inch 60 inch focus refractor lens in front of the Hypo system up on test. I could place images close to the bench and control them. The first image is the optical layout of the system. This hypo array uses an achromatic reduction lens. The test is to qualitatively assess the amount of colour aberration in the images.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5565767 - 12/11/12 11:30 AM Attachment (21 downloads)

The second image is an artificial solar disc with an outsize spot, this to test a black and white image

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5565771 - 12/11/12 11:32 AM Attachment (21 downloads)

Note residual colour fringes typical of the Hypo system. The third image is of a brilliant star cluster.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5565774 - 12/11/12 11:36 AM Attachment (25 downloads)

Final image is to shew the amount of colour in a pattern of bright spots, these are RBG mix LED lamps, this colour aberration is the amount encountered with a Hypo.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5565779 - 12/11/12 11:38 AM

Mark, I now withdraw from the Arena

Post Extras: Print Post   Remind Me!   Notify Moderator  
ed_turco
Pooh-Bah
*****

Reged: 08/29/09

Loc: Lincoln, RI
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5565968 - 12/11/12 01:39 PM

Why do that; I'm very impressed with the new pics; very impressed!


Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: ed_turco]
      #5566163 - 12/11/12 03:42 PM

With the new series of pics, we still need to know the diameter of the camera lens's aperture with respect to the exit pupil under test. If the iris is smaller than the exit pupil, the system is stopped down and so performance will be artificially improved.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5567162 - 12/12/12 08:55 AM Attachment (12 downloads)

OK Ed here are a few more, these are all artificial images, IE illustrations from glossy mags, and in the case of the moon a picture post card, now these images suffer as a result of this reproduction. The intention is to see how various images are affected by the colour aberration, extended images show very little or none, re the moon and the ring neb, yet the star images shew colour splitting. Jupiter is another pic from a well known astromag, and here again the extended image shows little or no spurious colour Now I have seen colour splitting in images taken with SC scopes just as bad as the stars shewn here.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5567165 - 12/12/12 08:56 AM Attachment (10 downloads)

Next

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5567169 - 12/12/12 08:57 AM Attachment (10 downloads)

finally

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5567176 - 12/12/12 09:01 AM

MKV. I had to downsize the image to suit reqirements laid down, I would be happy to shew the tree larger than this.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5567207 - 12/12/12 09:28 AM

Glenn I have not a clue what size the camera lens is, as it is buried deep inside the digital, hard up against the detector. Most cameras these day have lenses which are nothing more than glorified pinholes, gone are the huge lenses we enjoyed on the old SLR film cameras, I know the more expensive and hugely complex digital cameras have larger lenses, but they are out of my league. For all that the ordinary run of the mill digital produces marvellously good images for general use due to the efficiency and high resolution of the imaging chip. Now what you say is true, a one mm aperture will cut down the OG quite a lot, but all of it is still used. Complex camera lenses are stopped down in varying amounts to suit light levels, never is the full wide open lens system used, (some do perhaps ), With the Hypo system I am using, the OG is stopped down but look at it as a camera lens and not a telescope in the way we use them for visual work. You might say why use a full aperture if it is only going to be used at one third aperture, so lets only use a smaller diameter OG, this does not work in the same way as leaving the system at full aperture, where as I said before, although it is stopped down, you are still using the full aperture, as it scans the full field of view. Incidently, binoculars, generally have an exit pupil of around 5mm, yet we use them in the daytime when the average human pupil is only 2 to 3mm. Everybody accepts this quite happily, as long as you can see the type of tail feathers a lesser spotted twit is displaying, it dont matter

Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel
*****

Reged: 02/01/08

Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5567232 - 12/12/12 09:42 AM

It images nice that is all that matters. Congrads John for this design. Mark will push the design and learn some . All good . To have a big single lens telescope is what ATMs dream off .

Post Extras: Print Post   Remind Me!   Notify Moderator  
Wes James
Postmaster
*****

Reged: 04/12/06

Re: Hypo/Dialyte testing discovery new [Re: kfrederick]
      #5567249 - 12/12/12 09:56 AM

I don't understand what the issue is of using an inexpensive, small sensor'd digital camera... digiscopers do it all the time with extremely effective and sharp results. The sensor in the typical small digital point-n-shoot is about the same size as the human eye- so putting a small digital point-n-shoot behind an eyepiece is as if your eye was placed behind the eyepiece. The main requirement for digiscoping is that high-range zoom camera's don't work... typical of a digiscoping candidate is a camera with only a 4:1 zoom range.

Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Wes James]
      #5567896 - 12/12/12 04:19 PM

In the case of a stopped-down system, as occurs when the aperture of the afocally employed system (camera or eye) had a pupil smaller than the telescope's exit pupil...

Assuming the camera's iris is correctly located in the plane of the exit pupil (as it should be for evenness of illumination, and especially when the iris and exit pupil are close to the same size), an image of the iris is formed at the object glass. And so all image forming light contributing to the image passes through this reduced central aperture at the OG.

And even if it were such that off-axis image-forming light passed through the OG offset from the latter's center (as though an off-axis mask were installed), the same reduced fraction of its aperture would be employed.

The point is that no one image point anywhere in the field is being formed by the full aperture of the OG, and so aberrations are reduced. Make up a 'telescope' using a single-element objective, which with a suitable eyepiece produces an exit pupil of about 2mm for daytime testing, or better yet 5mm for nighttime. The chromatic and spherical aberrations will be awful. Now place a mask up front which reduces the exit pupil to 1mm, or a bit less (starting from the larger, low-light exit pupil will make for a more dramatic change). The image, while dimmer, will be of rather better quality.

This is why I'm stressing the importance of knowing whether and by how much the afocal imager is reducing the effective aperture by virtue of its small iris. Any aperture reduction artificially improves performance, especially when the reduction is significant. And for the Hypo (in its simpler configuration), which is limited to larger exit pupils, images are only properly representative when the camera's iris at least comes close to equaling the exit pupil diameter.

One way to obtain an idea of the actual working aperture is to find the diameter of the circular obstruction which just blacks out the image. With the camera's iris located at the exit pupil plane, the eyepiece will form an image of the iris on the OG, the diameter of which is the iris's diameter times the telescope magnification. An obstructor having the same size as this projected iris will, when positioned on top of it, will just fully block all image forming light. Experimentally try successively smaller obstructors until one is found which just blacks out the image when positioned just so; this is, to reasonable accuracy, the effective aperture of the system.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5568064 - 12/12/12 06:35 PM

It occurs to me that using a front end occulting disk to ascertain the working aperture with camera can only work with full-auto cameras only when the camera's iris is already fully open. If the light level is high enough during picture taking to cause the iris to stop down, placing an occulter up front will cause the iris to open up wider than when actually taking the pics.

This leads to one approach to follow when assessing via afocal imaging. Do this at a low enough light level to ensure that the camera's iris is fully open. By zooming in at least somewhat, the increase in focal length should further increase the camera's own linear aperture. And as long as the coupling of exit pupil and iris allows (what with reduced eye relief distance), a shorter focal length eyepiece will aid in getting the exit pupil down to a size more in line with the camera's entrance pupil.

A closer match in the pupil diameters will provide in the pictures a more realistic visual impression of performance.

Does your camera, or the manual, provide specifications on the lens re. the focal length and aperture ratio ranges?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5568627 - 12/13/12 03:21 AM

Thanks Kfred, you see my point, My thinking is holistic, not reductionist, reductionists nick pick over small details and see faults in everything, nothing ever positive comes of it, the old saw that a camel is a horse designed by a committee is germain here. I am now pulling out and handed it back to Mark. Thanks Mark.

Post Extras: Print Post   Remind Me!   Notify Moderator  
wiseone
Vendor (Zerochromat)


Reged: 01/07/08

Loc: North Wales, UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5568668 - 12/13/12 04:35 AM

I sent some design results to Mark a week or so back for a 6 inch retro. The front lens and field lens are both BK7, and are easy to make. The corrective lens set is just a couple of small identical doublets. The tolerance to decentration is very loose, so it is not a problem to actually make. It is diffraction-limited over most of a 1 degree field of view, and would make a great all-round long focus refractor (f12), and under 4 feet long when folded. If anyone is interested, I can post the spot diagrams and Ray Intercept Curves.

Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel
*****

Reged: 02/01/08

Re: Hypo/Dialyte testing discovery new [Re: wiseone]
      #5568760 - 12/13/12 07:27 AM

Yes post them sounds great . Thanks

Post Extras: Print Post   Remind Me!   Notify Moderator  
wiseone
Vendor (Zerochromat)


Reged: 01/07/08

Loc: North Wales, UK
Re: Hypo/Dialyte testing discovery new [Re: kfrederick]
      #5568854 - 12/13/12 09:12 AM Attachment (29 downloads)

Here are the spot diagrams. First on-axis

Post Extras: Print Post   Remind Me!   Notify Moderator  
wiseone
Vendor (Zerochromat)


Reged: 01/07/08

Loc: North Wales, UK
Re: Hypo/Dialyte testing discovery new [Re: kfrederick]
      #5568855 - 12/13/12 09:14 AM Attachment (22 downloads)

Off-axis

Post Extras: Print Post   Remind Me!   Notify Moderator  
wiseone
Vendor (Zerochromat)


Reged: 01/07/08

Loc: North Wales, UK
Re: Hypo/Dialyte testing discovery new [Re: wiseone]
      #5568859 - 12/13/12 09:16 AM Attachment (26 downloads)

And Ray Intercept Curves. By the way, the whole refractor can be made from BK7 and F2 glass types, with only a small loss in performance. Easy for experienced ATMs to make!

Post Extras: Print Post   Remind Me!   Notify Moderator  
ed_turco
Pooh-Bah
*****

Reged: 08/29/09

Loc: Lincoln, RI
Re: Hypo/Dialyte testing discovery new [Re: wiseone]
      #5568970 - 12/13/12 10:37 AM

I hate to jump in here and be a jerk. This is not a disparagement of anyone or the designs mentioned.

Why not use a corrected singlet in a refractor, say f/12 or so and use a filter? Any thoughts?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: ed_turco]
      #5568995 - 12/13/12 10:48 AM

Ed I did this using R G and B interference filters, refer back to page 6. Yes, monochromatic scopes work fine, even if images are red green or blue, great on the moon but a bit dim for fuzzies to be seen. The spherochromatic ab disappears using discreet filters and the images using a singlet OG are extremely good.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Scout92
member


Reged: 12/20/11

Loc: Hoquiam, WA.
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5570710 - 12/14/12 11:40 AM

Would a six inch +meniscus from suplusshed work?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Scout92
member


Reged: 12/20/11

Loc: Hoquiam, WA.
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5570796 - 12/14/12 12:40 PM

Mark I am fascinated by your experiment and am tring to understand John's hypo as well, however I have very little understanding of optics so it is coming slowly. Keep up both the good work and the posting I would love to see what you come up with and maybe try to create one of my own. Take your time and explain at your pleasure...I am all ears!

Post Extras: Print Post   Remind Me!   Notify Moderator  
ed_turco
Pooh-Bah
*****

Reged: 08/29/09

Loc: Lincoln, RI
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5570906 - 12/14/12 02:06 PM

Who needs fuzzies? I'm a Lunatic!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: ed_turco]
      #5571967 - 12/15/12 03:22 AM

Scout 92, you should try to build a Hypo keeping STRICTLY to my specifications, and use a low power eyepiece to get anything from X16 to X25. You will then see what a Hypo can do. If you dont like then OK, no sweat, but at least you tried to see one for yourself, instead of just shooting it down in flames because it does not conform.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5571971 - 12/15/12 03:26 AM

Scout 92 again, I know the meniscus you are talking about, it comes from surplus shed, be careful, they are suspect, and they are a meniscus lens, which aint a very good lens for inaging.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5572058 - 12/15/12 06:29 AM

The Hypo can be built, as John says- and stick to a low power setting.
My dialyte is different. It requires tighter tolerances, but not nearly as much as an achro, or apo. Also, I don't know of any place that sells what I am discussing here- I have to fabricate most, if not all the parts (though a low-medium power eyepiece I believe, can be made expeditiously from S/S parts)
I think the way it's going to work out (dialyte) is that by correcting lateral and longitudinal color in 2 different places, good imaging and correction can be had without the tight tolerances. So far, longitudinal color can be made by changing spacings by 1/16-1/8" when tinkering with OSLO. If all goes as planned, I will wind up with something that performs about as well as an achromat.
****
At present, I'm roughing in the curves on the "zero" power achromat. Think of finish- generating a curve of ~17" with 220 grit on the flint! (SF1, really soft stuff!)
****
I would be a bit cautious about the 6" PCX lenses from the Shed- heard (though haven't confirmed personally) that they could be a bit sloppy. But they could be cleaned up with a pitch polisher???
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5572062 - 12/15/12 06:36 AM

And how does a meniscus objective singlet compare to a PCX? Or DCX? The altered shape is expected to have some impact, methinks, at least for the 'faster' lenses like this f/17 from the 'Shed.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5572068 - 12/15/12 06:55 AM

I made this meniscus (concave back) so that I can use typical aspherizing technique to make this concave surface a hyperboloid. It affords tilting the RGB color correction on the longitudinal graph so that they're straight up and down; shrinks the spotplots quite a bit. Left spherical, it tips these lines off vertical, and blows the spotplots.
****
The shallower the concave back, the more correction it needs. There is a point where you can deepen the curve by bending the meniscus, and just have paraboloidal correction; and even spherical. But that makes for pretty steep curves which necessitate a thick blank to start off with. (a lot of grinding there)
So I picked curves that would fit a typical BK7 moulded blank that used tooling I already have on hand. (call me lazy)
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Aljr
member


Reged: 12/08/10

Loc: BRAZIL
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5572171 - 12/15/12 08:45 AM Attachment (16 downloads)

Quote:

Words of Mark Harry: I would be a bit cautious about the 6" PCX lenses from the Shed- heard (though haven't confirmed personally) that they could be a bit sloppy. But they could be cleaned up with a pitch polisher???
M.



Mark, you're right. This lens PCX is hardly polished, but it is made of white glass. It is necessary to make a new polishing. I can say that the lens "PMN(positive meniscus)" is/has superior quality.
I used the lenses PCX "Surplus Shed" in Hypo as if these were "good quality lenses". That's how I took a "giant / big man" with feet of clay.
I would like to warn that "Stipe Vladova" of Croatia, was the person who first tested the PCX lens.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Scout92
member


Reged: 12/20/11

Loc: Hoquiam, WA.
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5572469 - 12/15/12 11:55 AM

Quote:

Scout 92, you should try to build a Hypo keeping STRICTLY to my specifications, and use a low power eyepiece to get anything from X16 to X25. You will then see what a Hypo can do. If you dont like then OK, no sweat, but at least you tried to see one for yourself, instead of just shooting it down in flames because it does not conform.




Jon,

I plan on building (already strarting to collect materials in fact) trouble is I have no clue where to find a lens like the one you discussed so I have to research that and as of right now do not have he skills to produce on my own. As soon as I get the materials I will check it out and form my own opinion (don't understand most of the opinions on here anyway...yet) thanks for the advice and I enjoyed reading your original hypo thread.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Aljr]
      #5572483 - 12/15/12 12:01 PM

As I said watch out for those lenses but they are the right focal ratio for a simple Hypo, you must repolish them. Remember they must be F:40, bottom limit F:30.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5572501 - 12/15/12 12:12 PM Attachment (25 downloads)

Image of a security light taken with a 76mm F:40 PCX OG using a 7 X 50 bino OG for the reduction lens. fuzzy due to misty night. Note lack of colour.

Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel
*****

Reged: 02/01/08

Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5572683 - 12/15/12 02:22 PM

Mark does the BK7 polish faster than Pyrex??

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Aljr]
      #5572890 - 12/15/12 05:20 PM

I discovered something that might be of value, whether you're making a Hypo, or Dialyte.
****
I have my meniscus sitting on a windowsill. The conjugate focus (with objects outside) happens to be where a chair is placed in the room.
I picked up a pair of binoculars, and took a look. The lens aperture was totally a blur, and a uniform color. Strange, I noticed that just using my eye, the color resolved into fuzzy blobs.
So I went downstairs, and drilled a 1mm (.040") hole through a piece of sheet metal. (smallest I had)
The blobs of gray, white and green seen with naked eye resolved into treebark, and evergreen individual pine needles, with their characteristic curved tips!
The bark grooves off an ash tree are vertical, so I swept the grooves across the lens aperture, and the dark lines representing the grooves revealed straight lines to within 1/32" of the meniscus edge on the concave side. My methods and theories of polishing remain intact!!!
I could see these edge issues on each surface, but using an apertured hole to view through sharpened things up to an excellent degree.
The hole I am sure, apertured the lens down to a smaller virtual lens, but being near my eye, allowed me to see the whole aperture, and some of the surrounding background, all at once.
There are individuals who would call it preposterous that I could test edges and general conditions simply by eye, but it is possible; if you pay attention to what you can see. Experience can be a big help as well.
Aljr, mine looks very smooth cmpared to your pic. No trace of zones.
M.

Edited by Mark Harry (12/15/12 05:27 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5572895 - 12/15/12 05:24 PM

BK7 is very similar to pyrex for polishing time; maybe slightly less (with pads).
This piece as far as waiting to test or otherwise take a look, posed absolutely no problems; and displayed hardly any stress at all using polarized light. Nice piece of glass.
M.

Edited by Mark Harry (12/15/12 05:28 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5572908 - 12/15/12 05:34 PM

Even though I have just the meniscus objective, I can see more detail, than with naked eye, by far. With a "pinhole" in daylight anyways; using my eye and the aperture stop. I would like to see using a 3/4 and 1/2mm (.030, .020") pinhole would show.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5573517 - 12/16/12 01:29 AM

Mark,
I know what you mean about the surprising sensitivity of the bare eye when near the focus. When figuring 12.5" f/2 ellipsoidal primaries for a CDK, to quickly see if I'm keeping the very edge under control I use the reflected image if the light fixture overhead. The fine pattern of 'diamonds' in the clear plastic diffuser, when observed as I move my eye laterally, can let me know if the edge is beginning to turn, thus warning me to move the *very* sub-diameter polishing tool a tad farther in from the edge. And this is at f/2, where sensitivity is much lower than at longer f/ratios.

I discovered this somewhat by accident, after noting the not-too-subtle difference in reflection after a spell of overcorrection, as revealed by a tiny test plate made specifically for monitoring the very edge. Thereafter I found that once the proper variation in slope was achieved, with very little practice a departure of about 1/2 fringe over the 1/4-1/3 inch edge zone width of concern could pretty reliably be detected by the eye alone when scrutinizing the way the reflected image modulated as it was made to sweep across said zone, where the slope variation amounted to a good 5-6 fringes.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5573588 - 12/16/12 03:37 AM

This is termed "reading an optic", you will find reference to this technique in ATM somewhere, I do it by looking through an OG under test at a distant object, and put a vertical of some sort in the field, then place the eye at the focus, you can see exactly the condition of the optic, turned edge zones, roughness etc, another way is use the edge of the iris in the eye as a knife edge and do a crude Foucault test, this gives the figure trend as you go along. I peer through commercial scopes sometimes and can see how bad they usually are.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5573721 - 12/16/12 08:17 AM

Glen:
-PRECISELY-! I use a light source regularly for a quick look!
******
I can add, the back side of this meniscus is about 122", equating to an 8" F/7.6~. The stroke needed to get rid of the pad polished edge had to be known on the outset. I reduced it to the point of getting a hint of a diffraction line showing, and figured the rest should be obscured by a cell made to hold the lens. Gratifying to see it's so narrow now. I tested it only once, and it's interesting to see the verification with such a simple pinhole.
The other thing- using just the pinhole with the lens can be used as a makeshift scope of sorts with suprising detail.
The lens is facing out toward the barn around 30 yards away. When fully illuminated, it projects a highly detailed image of the face of the barn on the wall- a camera obscura. The aperture is large enough to make a good image even when the curtains are open. The image is 4 feet tall, and 6 feet wide. The conjugate just so happens to be close to the width of the room.
This would make a good educational example to bring to a school...
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5576985 - 12/18/12 09:20 AM Attachment (15 downloads)

This specification works very well for imaging and visual viewing. The spec shews the OG as F:31, this is the bottom limit. Two images taken through this scope of test objects. The images were cleaned up in photoshop, the colour was not tampered with.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5576991 - 12/18/12 09:22 AM Attachment (16 downloads)

First image

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5576994 - 12/18/12 09:23 AM Attachment (22 downloads)

Second image

Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Jones
Carpal Tunnel
*****

Reged: 04/06/04

Loc: Sin-sin-atti
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5577060 - 12/18/12 10:26 AM

For only $39 you can pick up an 80 mm diameter achromat from Surplus Shed 400 or 900 mm focal length. I'm sure it will perform much better and have less color.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Ed Jones]
      #5577100 - 12/18/12 10:53 AM

Ed Where can you see the colour in these images ???. So you can get an achro for cheap so what! I am pushing new idea for the inventive and imaginative ATM here. But it seems I am having very little success.

Post Extras: Print Post   Remind Me!   Notify Moderator  
ed_turco
Pooh-Bah
*****

Reged: 08/29/09

Loc: Lincoln, RI
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5577201 - 12/18/12 12:08 PM

At the eyepiece your eye does not process with photoshop. Please show the images as they are.


Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: ed_turco]
      #5577210 - 12/18/12 12:12 PM

Quote:

At the eyepiece your eye does not process with photoshop. Please show the images as they are. Ed



Ditto!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Jones
Carpal Tunnel
*****

Reged: 04/06/04

Loc: Sin-sin-atti
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5577225 - 12/18/12 12:22 PM

Quote:

I am pushing new idea for the inventive and imaginative ATM here



The goal should be something that's an improvement.


Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel
*****

Reged: 02/01/08

Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5577235 - 12/18/12 12:28 PM

John is TRYING to share some of his cool design . I like the effort and am glad he shared . John builds his ideas and shares the results .Easy for some who has NOT used this type of telescope to tell the guy who invented and built it and owns it and HAS USED IT is is no good . John you are the ATMs ATM .

Post Extras: Print Post   Remind Me!   Notify Moderator  
MKV
Carpal Tunnel
*****

Reged: 01/20/11

Re: Hypo/Dialyte testing discovery new [Re: kfrederick]
      #5577366 - 12/18/12 02:03 PM

K Fredrick, and I think Ed Turco was TRYING to convey that the images John presents here are not what you see at the eyepiece, but Photoshoped RGB photo art. No one is trying to deny John's inventiveness or willingness to share, but what is shared should be WYSIWYG (what you see is what you get).

Mladen


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5577471 - 12/18/12 03:15 PM

My main concern with Jon's 76mm Hypo prescription above is the very nearly 10mm exit pupil. A point and shoot camera's effective aperture in daylight conditions might be near the 1mm range, meaning the scope's effective aperture is probably less than 10mm (!).

I assume all ATMs understand the effect of stopping down an aperture. And that this stopping down occurs at the exit pupil offers no escape clause in the laws of optics. What accurs at the exit pupil is projected onto the entrance pupil. Stop the exit pupil down to 1/10, and the entrance pupil is correspondingly stopped down to 1/10.

Ray trace the system with a 7.6mm stop placed at the OG (now operating by itself at f/310.) The now *very* slimmer light cone passing through both the singlet and doublet will greatly supress at least the longitudinal aberrations.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: MKV]
      #5578342 - 12/19/12 03:34 AM Attachment (23 downloads)

Thanks guys, nice of you to say that. Now here are the two images before massaging them in photoshop. All I did was size them to fit this forum requirements. Oh a point I think critics should take on board, what do imagers do but alter their images and process them to get the wonderful images that they can achieve electronically, when the actual image as seen visually through the telescope appears as a faint greenish smudge.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5578346 - 12/19/12 03:36 AM Attachment (24 downloads)

And

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5578379 - 12/19/12 04:15 AM

Glenn I think I explained how the system works as a camera lens works in a previous post. Now, I say, does it matter! as long as you get nice images. look at the cleaned up images of the antenna and house frontage, the fine detail is very good. Do you have to use a telescope at absolutely the full aperture all the time?, usually telescopes are not, and visually the diameter of the pupil is never fully wide open to suit the design parameters of the scope in question, At best most observers never do. Now a camera lens is not used at the full aperture of the front element, it is not designed to do so, and here the Hypo is acting as a camera lens.

Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5578485 - 12/19/12 07:17 AM

If a 76mm aperture scope is working at a 10mm exit pupil, and the observer's pupil is 5mm, the the scope is really working at 1/2 its nominal aperture, or 38mm. Therefore the outer portion of the objective is not contributing to image formation, and so the performance is improved.

Visually, about the largest portion of the 76mm aperture one can utilize is about 7/10 of 76mm, or 53mm. How is this an improvement on the 50mm doublet if used by itself? The big singlet up front is nothing more than an aberration-inducing hunk of glass which essentially adds nothing to light grasp.

In order for the added singlet to even begin to pay its way, it must materially increase light grasp. And so the exit pupil must be not so much larger than the eye's pupil, or the camera's entrance pupil, that the effective aperture of the system be hardly larger than the doublet alone.

This is like a 7X50 bino used in bright daylight. The observer's pupil is about 2.5mm, and so the real aperture is 50 * 2.5 / 7 = 17.9mm. That is, the 7X50 bino is working instead just like a 7X18. If the bino suffers noticeable aberrations when the observer's pupils are 7mm (or nearly so), those aberrations will certainly be much diminished or eliminated in the daytime.

And so it likely is the case, too, if your camera's entrance pupil is much less than the scope's exit pupil.

How about affixing an eyepiece which delivers an exit pupil closer to a couple of millimeters (as opposed to 10mm) and take some pics for us?

Or at least supply the camera lens's focal length, from which can be derived a likely entrance pupil diameter for it. This will suggest a close-to-matching exit pupil.

I belabor these issues for three reasons:

1) In order to assess the relevance of the supporting images, it's mandatory that it be known whether the system is working at least near to full aperture.

2) To be satisfied with muddling along without understanding the test apparatus and the requirements for its effective use cannot be expected to inspire confidence in the reader.

3) If it's known or even suspected that the images are taken at less than full aperture, to not disclose this smacks of misrepresentation.

While I certainly don't demand the strictest adherence to the precepts of the peer review process, at least paying some semblance of lip service to the scientific method will go a long way. Surely this is not too much to ask among a community of instrument designers and makers.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5578518 - 12/19/12 08:04 AM

I have a question:
***
What I'm looking at with just a meniscus lens sitting on the windowsill, and using a piece of sheetmetal with various holes in it...
If I use 1.25mm hole (~.050") and looking 50 yards away roughly, I can see a Frasier fir, and I can see the individual twigs as a round green stalk, only seldom seeing individual needles. If i switch to a 1mm hole (~.040") I can see practically all the individual needles on each twig, at a decidedly reduced light level.
Both cases, I am somewhat inside focus- and I can get closer to the lens, and get less magnification, somewhat sharper detail.
But to mention what's puzzling, I see that Glen is right- I am likely not using the whole aperture. But I can see the whole lens, and additional background besides- So exactly what is happening? I can use this to also check the edges of the lens- just look at any vertical line as it approaches the periphery, and view whether it has any hook or not.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5578714 - 12/19/12 10:44 AM

Actually the outer portion of the OG is used, field angle dictates that. What happens is that only a sub aperture zone is used by the eye for all parts of the OG diameter, this happens with a stopped down camera lens.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5578758 - 12/19/12 11:23 AM Attachment (32 downloads)

This highly simplified diagram illustrates the point I just made.

Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5579396 - 12/19/12 06:28 PM

Mark,
In the test you describe, you're using the lens like a simple magnifier. Indeed, because you're so far back from the lens, you must employ an aperture stop (the pinhole) in order to obtain good focus via an increased depth of focus. When you examine any particular, small detail, note its apparent size with respect to the lens; this tells you the maximal fraction of the aperture contributing to the formation of any one image point.

Now this is not *quite* the same as when testing a complete system in the afocal configuration.

Jon,
Your diagram does indeed get to the issue of stopping down of the system. However, it does require a further refinement, because the OG defines the entrance aperture.

The image-forming light for an off-axis image point still passes through the central zone of the OG, along with the light for an on-axis point.
In your sketch, you have the light cone for the off-axis ray bundle passing through the same center-of-field point at the focal surface as for the on-axis bundle. An off-axis image point is displaced from the center of the field, which here would be below the optical axis.

With this in mind, a ray trace will show that all image-forming bundles from all parts of the field pass through the same reduced central zone on the OG. Again, this is due to the OG defining the entrance pupil.

Here's another way to understand this. The exit pupil is a reduced image of the OG (technically, the entrance pupil) formed by the eyepiece. And the same works in reverse; anything at the the exit pupil is projected upon the OG by the eyepiece. For example, an iris located centrally at the exit pupil, and having half the diameter of the exit pupil, will be projected onto the OG, filling the central one-half of the OG. All image-forming light, no matter where from across the field of view, which passes through the reduced iris (at the exit pupil) must necessarily pass through this central half-diameter zone on the OG; the outer zone of the OG does not contribute to image formation anywhere across the field. And again, this is because the OG is the entrance pupil.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5580006 - 12/20/12 03:09 AM

No the stopping down of the pupil does that, all over the real aperture. The larger the pupil the larger the stopped down aperture all over the real aperture, until the limit is reached when pupil aperture equals real aperture.

Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5580042 - 12/20/12 04:03 AM

Jon,
Revisit your previous illustration to identify the flaw whereby you show a light bundle coming from a point off axis (at the field edge) and coming to focus at the same point as does an on-axis image point. The off-axis bundle arriving from the upper left will come to focus below the optical axis, and not at the same place as for an on-axis image point.

Once this is rectified, a correct ray trace will show that the off-axis bundle will pass through the same central zone on the OG as for an on-axis bundle.

I should post an image showing this...


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5580389 - 12/20/12 10:36 AM

You are absolutely correct, a drawing error, done in haste, but the argument still holds.

Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5580742 - 12/20/12 01:49 PM Attachment (22 downloads)

Jon,
In this illustration, the relevant system is at the bottom, which is the same as the one at the top except for the system being stopped down by a smaller iris at the exit pupil.

The only rays which make it through the reduced iris are those which pass through the reduced entrance pupil; the outer zone of the OG does not contribute because any image-forming light passing through here is intercepted by the reduced iris.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5580769 - 12/20/12 02:06 PM

An additional thing to study. In the lower illustration, follow the three rays passing through the upper edge of the reduced entrance aperture on the OG. The red, white and blue rays diverge from a point, pass through the eyepiece, and are then brought to a focus at the lower edge of the reduced iris. This shows how the eyepiece is a kind of two-way projector; it focuses the image of the entrance pupil at the exit pupil, and focuses the iris at the entrance pupil.

The eyepiece is the optical coupler between the objective and the eye (or camera) in the afocal configuration. If the iris is smaller then the exit pupil, the eyepiece projects an image of the iris onto the objective, the latter defining the new working aperture of the system.

I had assumed all ATMs were well aware of this optical principle.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5581867 - 12/21/12 04:38 AM Attachment (17 downloads)

Please do not patronise me Glenn, If I did not know the basics of geometrical optics I would never have been able to invent the retro focally corrected dialyte. during the period I was developing the idea I performed a vaste amount of calculation and analysis involving complex application of geometric optics; as I have mentioned previously, one of the top optical designers in the UK took my basic invention and found that it could be made apochromatic, and he built one and it was!. When I invent a system I resort to experimental physics techniques and have a home optical lab to do verification experiments of any hypothesis I have come up with. Many times I have been wrong , but also, many times I have been right. I might mention that I do have a science degree, as now doubt you have. So about our argument, I quickly set up an experiment to see if I was actually wrong!, not to shoot you down. It seemsthat my argument was right, as the images I send you verify, yes made a blunder with my previous optical diagram, a greenhorn mistake, but we all make em dont we. The first image shews a mask that will be placed over the five inch OG of a non achro Hypo I currently have on test on the bench. In it is cut a circukar hole one inch diameter placed close to the edge. The second image was taken with the full; aperture of the system IE five inches. The second image is an image formed by the one inch aperture at the edge of the OG, a lousy image yes, but adequate. The final image is the mask in place over the OG of the array on the bench. Note then that the configuration I have been arguing over does work as I suggested. Now I am pulling out of this thread as I have wasted too much time as it is arguing.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5581872 - 12/21/12 04:45 AM

I seem to be held up by the system not sending the rest of my images, I will try later.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5581877 - 12/21/12 04:49 AM Attachment (15 downloads)

The one inch aperture at the edge image

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5581879 - 12/21/12 04:50 AM Attachment (15 downloads)

The central five inch image

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5581880 - 12/21/12 04:51 AM Attachment (15 downloads)

The aperture plate on the OG

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5581884 - 12/21/12 04:56 AM

Correction, image No 2 in the sequence is taken with the one inch edge stop placed over the OG.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5581924 - 12/21/12 06:11 AM

Glen, I understand now. I estimate the resolution is approximately (but not quite) similar to the singlet lensed Galilean telescope I made, which is around 38-40mm... roughly a 5th of the total meniscus diameter. (wider field though, where most of the color error resides.) Pretty neat fiddling with this; am learning useful tidbits along the way.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5581958 - 12/21/12 07:21 AM

Jon,
I'm not trying to patronize you, or anyone. As to education, I'm just a high school grad (grade 11, age 16, 1979, in the province of Newfoundland.)

If the latest images you took through the masks were afocal also, then of course you can obtain an image simply by moving the camera laterally to pick up light from that portion of the exit pupil which is illuminated.

That is, an off axis mask offsets the reduced exit pupil from the optical axis. Try this experiment:

With the OG *not* masked, mount a piece of tracing paper in the plane of the exit pupil so that it cannot move, then trace the pupil. Install the mask centrally, and note the reduced exit pupil centered on the optical axis; trace the circle on the paper. Now locate the mask halfway from center to edge on the OG, and trace the new exit pupil. Place the mask at the edge of the OG, and trace the exit pupil again.

You should see that the exit pupil has shrunk and moved just like a miniature version, to scale, of what's going on up front.

If an iris equal in size to the reduced pupil were placed in the plane of the exit pupil, it should now be seen that light passing through portions of the OG not contributing to that smaller pupil does not contribute at all.

Reexamining the case where the full aperture contributes to image formation (where the iris is at least as large as the exit pupil), note how both the on-axis and off-axis bundles entering the OG share the identical extent of the entrance pupil. Why, in this case, does not the off-axis bundle tend to be offset from the optical axis, at least to some small extent? If not in this case, then why should it be so when the system aperture is stopped down?

Another way to look at it: Say we have a system wherein the exit pupil and iris just match in size (like the upper one in the diagram I supplied above.) The existing objective is removed and is replaced by one of identical focal length, but larger aperture. Does that new, extra annulus on the OG contribute to image formation? No, because the entrance pupil is already as large as needs be for the iris. Now, incrementally enlarge the iris, and a corresponding incremental increase in the entrance pupil will occur, until the iris diameter equals the new OG diameter divided by the magnification. The entrance and exit pupils are the apertures through which all image-forming light must pass, irrespective of field angle. And each is a 'mirror' of the other, as defined by that optical coupler, the eyepiece.

[IN EDIT: Clarified the first line of paragraph #4. Added the final paragraph.]

Edited by GlennLeDrew (12/21/12 03:41 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5582637 - 12/21/12 02:58 PM

Yes, Glenn!
This is my whole point about this thread. Why can't the longitudinal color be solved with an achromat; and the lateral color be solved at the eyepiece???
Sure, the eyepiece to a purist will not be up to standards, but it should work well with this scope.
It works against the supposed idea to get any arbitrary eyepiece to work fairly well with any scope of various types-.
---but to get a dedicated eyepiece to work with a scope that would be essentially perfectly complimentary with each other... and to never fool around with a large piece of flint glass for matching the objective...
And the eyepiece would be cheaper, and easier to make by the ATM...
I'm persueing this on the premise that performance with short focal length eyepieces will differ very little. Just to have a low power eyepiece or two to work well at low power would be sufficient.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5582740 - 12/21/12 04:08 PM

Mark,
Indeed, the color errors must be addressed, as evidenced by the smorgasbord of rainbows in evidence even with an aggressively stopped-down Hypo. Sub-aperture correction is a most attractive approach. As to lateral color, have you developed a 'feel' for the best place for the singlet with respect to the eyepiece? It would be a shame if it had to be placed behind, thus robbing some eye relief.

By the way, I'm developing the feeling that in the main, knowledgeable amateurs can discuss such things as aberrations, spot plots, interferograms and what not, with more authority than they can the relationship between entrance and exit pupil as I've been hammering away at here. Can this be so? Such fundamental concepts are important, dealing as they do with that all-important interface between objective and eye, the exit pupil.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5583069 - 12/21/12 07:18 PM

Well, the focus of the objective in relation to a Ramsden allows the objective to come to focus first; lateral color and all. (that's what I'm counting on) The Ramsden should compensate or remove at least a significant portion of that problem since its layout relies on being after the focus of the primary...
Your mention of "pupils" is exactly why I'm piddling around with the meniscus of my scope. Plenty of aspects to be aware of in understanding the fundamentals, etc.
May this find you well,
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5583098 - 12/21/12 07:35 PM

Jon,
It suddenly occurred to me that the behavior you ascribe to off-axis imaging-forming light passing through the OG is exactly as occurs in Galilean telescopes. In such, the negative ocular locates the exit pupil lies inside the instrument, which of course is inaccessible (as if that would matter in any event ). In the Galilean, the field of view depends directly on the OG aperture; reduce the aperture and the FOV is reduced in step.

But in positive systems having the exit pupil behind the ocular, reducing the aperture can only reduce illumination uniformly across the FOV, provided the exit pupil is not larger than the iris. In the latter case, illumination does not change, doing so only when the exit pupil becomes the smaller.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5583683 - 12/22/12 08:17 AM

Glen,
The correction at the eyepiece has to be made past the objectives primary focal point 'somewhere'. I could either make an actual RAMSDEN (think I have some spare lenses that I could do so) or use an achro, with a singlet for a 3-element; 2-group eyepiece of sorts. Haven't really done much yet, for I still have to make the 4.5" achro.
I did use spotplots in OSLO of the dialyte, and a Ramsden eyepiece. Sized them to be identical scale, and printed both out on the same sheet, and it APPEARS that it might work pretty well.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5645480 - 01/27/13 04:56 AM Attachment (18 downloads)

I built a Hypo to my own specs using an F:40 127mm OG and a75mm Bino OG reduction lens. I took some images afocally. Visually at X30 where the exit pupil is 2mm, the same as my eyes, I was looking through the full aperture of the scope. I could only see a very faint colour splitting at the edge of the field, the images are very sharp and bright. The scope is as good as an achromatic.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5645481 - 01/27/13 04:57 AM Attachment (18 downloads)

Terrestrial snow scene.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5645487 - 01/27/13 05:04 AM Attachment (17 downloads)

This is an image taken in th optical bench array, the star cluster is produced by pinholes in a foil overlaying an LED source.

Post Extras: Print Post   Remind Me!   Notify Moderator  
wiseone
Vendor (Zerochromat)


Reged: 01/07/08

Loc: North Wales, UK
Re: Hypo/Dialyte testing discovery new [Re: Mark Harry]
      #5645491 - 01/27/13 05:12 AM

Hi Mark, I am enjoying this thread, and to add my two penn'orth, you can see what a simple achromat plus dialyte corrector elements does. Have a look on my web site - www.firefly85.com. I haven't pushed this yet, as there were some mechanical issues to sort out. This has now been done, and I plan to get this going this year.
Best wishes,
Peter


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: wiseone]
      #5645508 - 01/27/13 05:32 AM Attachment (22 downloads)

Faux Jupiter.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5645510 - 01/27/13 05:34 AM Attachment (17 downloads)

Another snow scene, note lack of colour in these images.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5645514 - 01/27/13 05:39 AM Attachment (20 downloads)

Finally for now, antennae. In this you can see the small amount of colour that is left in the images.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Jones
Carpal Tunnel
*****

Reged: 04/06/04

Loc: Sin-sin-atti
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5645786 - 01/27/13 10:45 AM Attachment (18 downloads)

The closest doublet I could find to your design is a Ross L-AOC306 which gives the spot diagram below for C,D and F. The little black dot in the center is the airy disk with a 72 micron blob of CA around it. Why don't I see all this color in your photos?

Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: Ed Jones]
      #5645985 - 01/27/13 12:36 PM

Ed,
Imagery at sufficiently low magnification/image scale will not reveal all aberrations evident visually at small exit pupil diameters. And as I've harped upon here previously, if an afocal camera has an entrance pupil smaller than the exit pupil, the resulting image will evince an artificial improvement due to the smaller-than-full-aperture system pupil.


Post Extras: Print Post   Remind Me!   Notify Moderator  
ed_turco
Pooh-Bah
*****

Reged: 08/29/09

Loc: Lincoln, RI
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5646742 - 01/27/13 07:19 PM

Quote:

I built a Hypo to my own specs using an F:40 127mm OG and a75mm Bino OG reduction lens. I took some images afocally. Visually at X30 where the exit pupil is 2mm, the same as my eyes, I was looking through the full aperture of the scope. I could only see a very faint colour splitting at the edge of the field, the images are very sharp and bright. The scope is as good as an achromatic.




If the exit pupil is 2mm and the magnification is 30x, you are looking thu a 60mm telescope, not a 127mm one.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Hypo/Dialyte testing discovery new [Re: ed_turco]
      #5647193 - 01/27/13 11:44 PM

Indeed, a 127mm objective and a 2mm exit pupil must provide 63.5X.

If both the magnification of 30X and the 2mm exit pupil are correct, the system is being stopped down to about half aperture. If this is the case, the culprit could be a too-long focuser drawtube for the faster-than-f/4 light cone behind the 70mm doublet.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: GlennLeDrew]
      #5648295 - 01/28/13 02:10 PM Attachment (12 downloads)

Star field test for colour with the F:40 Hypo. the field is 3 degrees wide.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5648299 - 01/28/13 02:11 PM Attachment (13 downloads)

The last image is the raw image, this image has been sharpened

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Hypo/Dialyte testing discovery new [Re: Crayfordjon]
      #5648327 - 01/28/13 02:21 PM Attachment (17 downloads)

The optical test bench with the F:40 optics mounted. OG to right, with white masking ring. Folding flat at the back. Red lens in foreground behind the focuser, and focuser at front.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | (show all)


Extra information
3 registered and 12 anonymous users are browsing this forum.

Moderator:  ausastronomer, richard7, Starman81 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 8097

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics