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MrBill's new APM Apos....

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#351 Mr. Bill

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Posted 29 July 2014 - 06:35 PM

It would be most interesting to compare the innards in detail with another bino such as the Miauchi Saturn...


Yeah....that's going to happen. :grin:

OK....here's a proposal. You buy an APM APO to dissect and I'll donate my APM semi APO for you to dissect and compare.

:cool:

#352 Rich V.

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Posted 30 July 2014 - 10:13 AM


It would be most interesting to compare the innards in detail with another bino such as the Miauchi Saturn...


Yeah....that's going to happen. :grin:

OK....here's a proposal. You buy an APM APO to dissect and I'll donate my APM semi APO for you to dissect and compare.

:cool:


We've talked about this before; the Saturns have an aperture stop just ahead of the rhomb. So do Bill's semi-apos I think. If he were to remove a turret I think he'll find the stop is 20mm or less. It doesn't change the effective aperture, just the illumination of the edge of the field with largest field stop eyepieces.

It's a trade I think would be worthwhile under the circumstances. Perhaps the Saturns are less effected because of it's longer focal length, though. Seems to work with the semis all right, however. They don't show the ghosting like the apos...

I'll happily break down my Saturns or Bill's semis to demonstrate the baffle placement. ;)

Rich

#353 Mr. Bill

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Posted 30 July 2014 - 11:16 AM

My conclusion after all this is that the ghosting caused by the clipped false pupils cannot be fixed with "bandaid" solutions, but is a design flaw which IMO lies in the prism train.

Using the eyepiece screw in aperture stops lessens the ghosting but it cannot be eliminated by either stopping down the objectives or the rear prism aperture.

#354 GlennLeDrew

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Posted 30 July 2014 - 12:08 PM

Bill,
It would seem the efficacy of the add-on stops is not so great because the better location for them would be ahead of the rhombs, where more of the unwanted light would be clipped before getting into the rhombs. Moreover, being farther up the light cone means they can be rather smaller than the field stop without inducing notable outer field darkening, which means yet more unwanted light is intercepted.

As I've written numerous times over the past several years, it's not at all necessary in a visual instrument to have edge-of-field illumination better than 50%. This kind of vignetting, when gradual, is discernible only by careful scrutiny, if then. And of course control of stray light is necessarily improved.

Virtually every Porro bino I've seen has the middle aperture--between the two prisms--as smaller than the other two (front and rear). This reduces the amount of light illuminating the rear prism's walls, and reduces the extent of the front prism's walls visible through the eyepiece.

#355 Mr. Bill

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Posted 30 July 2014 - 01:36 PM

Virtually every Porro bino I've seen has the middle aperture--between the two prisms--as smaller than the other two (front and rear). This reduces the amount of light illuminating the rear prism's walls, and reduces the extent of the front prism's walls visible through the eyepiece.


This presupposes the problem is the lack of or inadequate baffles between the prisms....we don't know which or whether it is the problem.

I am very reluctant to tear apart a $3K pair of binoculars to determine the problem (and voiding the warranty) with the distinct possibility that the prisms are indeed undersized for the light cone and nothing can be done to fix the problem.

I doubt that you would do it either if you had "skin in the game."

I will ask Markus if I can get a complete CAD drawing with all the parts shown. This would at least tell us if there is a baffle in between the prism sets and what size it is.

#356 Rich V.

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Posted 30 July 2014 - 02:28 PM

Bill, how hard would it be to remove the rear turret assy and see what you have? It's only a few screws, right?

We've seen the back comes off easily and photos have been posted showing the intertie linkage and rhomb entrances underneath. The front apertures of the rhombs are where I'd start experimenting with pasting some aperture masks. Maybe use a tiny amount of rubber cement with paper masks?

Rich

#357 GlennLeDrew

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Posted 30 July 2014 - 04:37 PM

I'm not at all suggesting to do any disassembly. Careful scrutiny through back end and front can tell much.

For starters, the immediately obvious fact of very high outer field illumination reveals that *somewhere* a restrictor can be installed without impacting effective aperture. This could be at the Schmidt's entrant face or between it and rhomb. The question is, which location would be best? And of course there's every possibility this by itself might not cure the problem fully.

A green laser could potentially be used as a probe. Aim it into the objective so that its light emerges out the false, clipped pupil, then observe its path through the prisms. It might require creativity to come up with a way to see the beam intercept points on the air-glass interfaces without getting in the way, and do it safely.
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#358 Mr. Bill

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Posted 30 July 2014 - 04:51 PM

I'm not at all suggesting to do any disassembly. Careful scrutiny through back end and front can tell much.

For starters, the immediately obvious fact of very high outer field illumination reveals that *somewhere* a restrictor can be installed without impacting effective aperture. This could be at the Schmidt's entrant face or between it and rhomb. The question is, which location would be best? And of course there's every possibility this by itself might not cure the problem fully.


I may be a bit dense, but how would either of these mods be done without disassembly, assuming that it could be determined which was necessary (using green laser)?

:question:

#359 GlennLeDrew

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Posted 31 July 2014 - 12:42 AM

The first order of business is to see if it can be determined by non-invasive scrutiny where a baffle might be more effective.

#360 Mr. Bill

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Posted 31 July 2014 - 10:26 AM

Markus has just told me that all future deliveries will have 21.5mm field stop installed instead of current 25mm.

:cool:

#361 kcolter

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Posted 05 August 2014 - 06:32 PM

I was asked a few weeks ago whether the Kowa HIghlander had any "fingernails" in the exit pupil. .  I finally got around to looking with the 21X eyepieces in place last weekend   I was going to reply directly to the person that asked me, but I can't find the PM function with CN's new look.   I could find no "fingernails" indicative of prism leak in the Kowa Highlander.   I compared to a Zeiss 7X42 FL that does manifest "fingernails" in order to make sure I was doing the maneuvers of my eye relative to the binocular that would reveal fingernails if they were there.  Kowa doesn't show any.    



#362 Mike Harvey

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Posted 05 August 2014 - 09:25 PM

Mr. Bill, et. al.

 

I finally got some decent weather and reasonably dark skies this past new moon and discovered that you're right about the 'fingernails' being an annoyance while sweeping. Following the Milky Way from Cyngus down through Sagittarius was a thrill....BUT.....I did use a few four-letter words if I swept too quickly and got "fingernailed"!

What is your opinion of what affect the new 21.5 mm field stop might have? Where would we reach the point of losing effective aperture or f.o.v.?

 

On the other hand, I got my all-time favorite view of the Double Cluster - with the APO's and 12.5mm Docters.

If the term "steely pinpoints" didn't already exist, this binocular/eyepiece combo would provoke someone to coin it!  

Most of my recollections viewing these clusters are that all the stars were just 'white-ish'. No more!

They are now a riot of colors. And that "orange" star between the two clusters is really, really orange!   :)

 

Also got what MAY be my favorite M-31 "family portrait"...31 showing sharply defined dust lanes, 32 looking like a small, unresolved, globular cluster and NGC-205 a silvery patch, hovering ghostly above the other two...all easily in the same field of view.


Edited by Mike Harvey, 05 August 2014 - 09:32 PM.

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#363 Mr. Bill

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Posted 06 August 2014 - 02:35 PM

"Mr. Bill, et. al.

 

I finally got some decent weather and reasonably dark skies this past new moon and discovered that you're right about the 'fingernails' being an annoyance while sweeping. Following the Milky Way from Cyngus down through Sagittarius was a thrill....BUT.....I did use a few four-letter words if I swept too quickly and got "fingernailed"!

What is your opinion of what affect the new 21.5 mm field stop might have? Where would we reach the point of losing effective aperture or f.o.v.?"

 

Mike....no problems with losing effective aperture or fov, but from my above comments using stacked filter cells and 21mm aperture stop attached to 19mm pan, this did NOT eliminate false pupils seen in exit pupil and so did not eliminate ghosting. The real solution would be a restricting aperture between the Schmidt and rhomb prisms, according to Glen LeDrew who is more knowledgeable than me in optical design.

 

One problem with 21mm rear prism aperture will be severe vignetting of 24 Pan eps which I enjoy using with the existing rear prism aperture  of 25mm.

 

A 4.2mm ep and almost 3 degree fov (23x) go a long way to make up for the ghosting issue. 

 

 


Edited by Mr. Bill, 06 August 2014 - 02:50 PM.


#364 Mr. Bill

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Posted 06 August 2014 - 02:46 PM

Question....how do I get attached images to above posts in this thread back??

 

:shrug:



#365 WOBentley

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Posted 06 August 2014 - 11:55 PM

The image transfer is still ongoing in the background. It is a very slow process...they should just show up at some point. Please remind one of us mods if you don't see them in a few days...we can recheck on progress.

Dave



#366 Mr. Bill

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Posted 07 August 2014 - 10:32 AM

Thanks, Dave....

 

:cool: 



#367 WOBentley

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Posted 07 August 2014 - 03:27 PM

I am told they are all transferred. A quick look shows pics in this thread... What I can't tell is if there are any stray pics that have gone missing...let me know (I would need specifics so we can look).

Dave


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#368 Mr. Bill

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Posted 12 August 2014 - 01:45 PM

Here is my 9/09/08 report on the Fuji 10x50s where I first observed this false pupil issue....

 

Lots of interesting discussion from EdZ....



#369 Mr. Bill

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Posted 17 August 2014 - 09:44 AM

Moon cycle finally cooperating with dark, transparent skies (SQM 21.5) showing off the summer Milky way with the Great Rift arching overhead fully articulated.

 

Spent two hours tracing the MW star clouds from Sagittarius to Cygnus with the APM APOs using 24 Pan, 19 Pan and 13 Denk eps. Each ep set had its own unique offerings of image scale and contrast viewing the intricate interweaving dark nebulae against a splashy background of stars.

 

I was lost in the detail that these binoculars provided....B92-93 in M24 revealed delicate spiderwebs of dark nebulae that could be traced out across several fields of view....much more subtle detail than seen in recorded images; the charm of visual observation that cannot be captured otherwise. It was a rare night that allowed me to "be the view" 

 

I want to repeat that the optics are capable of delivering stunning views, the ghosting issue aside. The sharpness, flatness and contrast are first rate and answer the question of whether or not they are worth the money with a big "yes." 


Edited by Mr. Bill, 17 August 2014 - 12:03 PM.


#370 RodgerHouTex

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Posted 17 August 2014 - 11:45 AM

Great to hear that you're happy with the APM APOs Bill.



#371 ianatcn

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Posted 18 August 2014 - 10:06 AM

Since my first outing with these binoculars the 10mm DELOS pair have remained in place. They are a great power for this binocular. I will try going higher when the moon is around. For now I am soaking up  the exceptional contrast and resolution that this setup provides. I do notice the ghost images when panning with 24mm eyepieces but in the 10mm Delos I don't notice it.

 

This is the best all round binocular I have owned and I used 25x150 and 40x150 Fuji in the past until, with advancing years they became too heavy to move around. I much prefer the APM apo to the Mayuchi 100fl that I used for the best part of 20 years. I would put the APM apo more on a par with the 40x150 Fuji than the Mayuchi. Being able to up the magnification on the APM is a really big advantage that cannot be overstated. That, together with the ability to use narrow band filters make them so much more versatile.

 

This is my personal opinion. Others may find the increased aperture of the Fuji (especially if blessed with really dark skies) make them more attractive. I find the combination of the APM apo and Delos eyepieces give an immersive experience that the narrower field of the Fuji do not. 



#372 ianatcn

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Posted 18 August 2014 - 10:07 AM

Oh and yes,  they are worth it!



#373 Mr. Bill

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Posted 18 August 2014 - 10:39 AM

Since my first outing with these binoculars the 10mm DELOS pair have remained in place. They are a great power for this binocular. I will try going higher when the moon is around. For now I am soaking up  the exceptional contrast and resolution that this setup provides. I do notice the ghost images when panning with 24mm eyepieces but in the 10mm Delos I don't notice it.

 

 

Interesting about the 10mm Delos....I ordered a pair and found them to be excellent but for me the exit pupil and fov was a bit restrictive for my type of observing. I sent them back.

 

I think the 12mm Delos would be more to my liking as I found the Docter 12.5mm to be a good medium power.

 

IMO, the 19mm pans are still the best overall combo for balancing fov/image scale for sweeping MW structure,  in spite of a bit of field curvature and pincushioning.

 

Adding the 21mm aperture stop to the 19 Pans really helps suppress the ghosting but does not eliminate it.

Attached Files


Edited by Mr. Bill, 18 August 2014 - 10:45 AM.


#374 GamesForOne

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Posted 18 August 2014 - 11:14 AM

I'm rather fond of the view from my Pentax XW10's in the APO bino. The magnification is excellent for medium-sized and smaller open clusters, as well as globs, galaxies, and a surprising number of double stars. The field with the XW10's is sharp to the edge and flat. Excellent with little ghosting.

 

My Pentax XW20's are not as good in the bino with some softening at the edges. The on-axis view is still quite good, but ghosting is noticeable with bright stars just outside of the field at certain angles. The contrast is still otherwise excellent. I still prefer the Pentax XW20 over the Pan 19 for reasons of eye relief.

 

I'm thinking about trying the Nikon NAV series if I can get the 17.5mm version for ~$260 direct from Amazon Japan.

 

---

Michael Mc



#375 Mr. Bill

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Posted 18 August 2014 - 01:39 PM

The other candidate for me would be the 17.3mm Delos. 

 

I know that they reach focus (barely) as I borrowed one off the TV rep at this years GSSP. It seemed the field didn't have the problems the 19mm Pan has...

the Delos was flat and in focus to the edge of the field.

 

They have about 2mm left before they bottom out.

 

That also means the 14mm Delos would work as both have the same fieldstop position relative to the ep shoulder.

 

Only cost me $600 to find out.... ;)


Edited by Mr. Bill, 18 August 2014 - 04:14 PM.







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