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


Extra information
12 registered and 22 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: 8081

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics