AO Triocular vs Beam Splitter

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Zuul
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Re: AO Triocular vs Beam Splitter

#31 Post by Zuul » Sun May 31, 2020 1:22 am

Phototube ready.
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apochronaut
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Re: AO Triocular vs Beam Splitter

#32 Post by apochronaut » Mon Jun 01, 2020 1:50 pm

That looks very nice. Fancy! What is the i.d.? That is somewhat critical; the bigger the better, since even though a smaller diameter allows one to image a full field, as the angle of any reflection on the interior walls flattens, it eventually reaches the point of reflecting incoming light into the photo eyepiece causing glare and loss of contrast.
It doesn't matter if the walls are flat blacked either; it still reflects. The only solution is either a large diameter or flocking.

Zuul
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Re: AO Triocular vs Beam Splitter

#33 Post by Zuul » Mon Jun 01, 2020 5:22 pm

The interior is quite spacious. I may flock it, regardless, once I have some flocking material on hand.

After experimenting with the set-up, I might not end up using this tube. With the 10x 437 eyepiece, the area of coverage is too small for my liking, even on a full frame sensor. Even a 5x eyepiece would still project a great deal beyond the edges of the sensor. So, without resorting to off-brand optics, I am looking at direct projection and started making a second adapter tube to experiment with.
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Scarodactyl
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Re: AO Triocular vs Beam Splitter

#34 Post by Scarodactyl » Mon Jun 01, 2020 6:00 pm

Are you doing direct projection onto the sensor? You might want to put a wide angle lens on your camera to resize and focus the image.
That is one heck of a snazzy adapter.

apochronaut
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Re: AO Triocular vs Beam Splitter

#35 Post by apochronaut » Mon Jun 01, 2020 8:49 pm

It looks like you copied the factory photo tube fairly faithfully, so I doubt if the issue with low contrast will be there. All AO did on those was flat black the inside and they work well. There is a knockoff on ebay, which may now have been improved but the original version needed flocking inside but there was very little room to do it. I think the i.d. on those was 5/8".
Direct projection will be tricky. You will need a short focal length lens and getting one with well enough corrected corners might be nightmare. You likely will end up cropping anyway.

The tube you made is so similar to the factory one that I would guess that it will perform as well as it. With an APS-C Sony sensor; so 23.4mm long, I use an external adapter that lifts that 437 eyepiece a bit inside it but yet the shank of the eyepiece is still in the tube. This lift is necessary in order to get parfocality. It's the distance from the eyepiece to the telan lens compared to the eyepiece to sensor. The distance to the sensor plane measured from the top of the casting that receives the tube into the trinocular port is 211mm. The surface of the eyelens on a 437 or 1054 eyepiece( the same) is 157mm above that casting, so eyelens to sensor is 54mm. Under such conditions the camera is parfocal with the # 176 eyepieces using a 10X ; 1019 objective. The APS-C sensor is also collecting the maximum possible area of the microscope field, with the corners of the frame, just barely inside the field stop under this condition.

In order to accommodate a full frame sensor with a similar set up, you need to just slightly increase the extension, bringing the camera out somewhat farther. The original emulsion film system for 35mm, so with the same frame dimensions, used a remote stand for the camera back and a bellows. That is possible or also to use a bellows above the photo tube but using some adapters and a helical focuser might be a better bet. One thing that does happen with a full frame set up and the required extension is the parfocality of the low power objectives changes some. It is particularly noticeable with the 2.5X and 4X, which will lose working distance in inverse proportion to the magnification. In a full frame set up I helped set up recently, where the owner wanted to maintain absolute parfocality between the objectives, I managed to shim the 2.5X , 4X and 10X to match the 20X focus. The extension above the eyelens to the full frame sensor was somewhere around 95mm, so using a helical focuser with enough throw plus an adapter to the photo tube that clamps on the outside and can move up and down the tube some allows for fine tuning the system.

Zuul
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Re: AO Triocular vs Beam Splitter

#36 Post by Zuul » Tue Jun 02, 2020 3:52 am

This is a very quick test of 2 different setups. One uses the #437 as a relay lens, and the other uses a 2X teleconverter. Aside from slightly different framing, can you see significant qualitative differences? Is one better?

The “subject” is a laser print. I wanted something that would be reasonably consistent across the frame. It was what I could think of in a hurry. No doubt there are flaws in the test but I had to start somewhere. Feel free to suggest improvements.

ImageAO 10 Photo Adapter Test TC by Mickey, on Flickr

ImageAO 10 Photo Adapter Test EP by Mickey, on Flickr

apochronaut
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Re: AO Triocular vs Beam Splitter

#37 Post by apochronaut » Tue Jun 02, 2020 10:04 am

The first noticeable thing is that both are displaying a bit of asymmetry. There is a falloff of corrections in the lower left corner of each image but in the second image it is worse. Something is out of alignment. How were these taken? It seems that you are capturing almost the entire image circle that the objective is capable of. The misalignment could be the objective being a bit off center.
To answer your exact question, though. Both show a bit of peripheral distortion, which is expected when you go to the extreme edge of a lens or lens system. The second image however, seems to have it worse, and also , maybe slightly worse contrast in general .
If I pick out specific details in what I would assume to be the area of the lens that would be used for framing. I would give the first image a higher score for contrast and resolution.

Zuul
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Re: AO Triocular vs Beam Splitter

#38 Post by Zuul » Tue Jun 02, 2020 1:43 pm

apochronaut wrote:
Tue Jun 02, 2020 10:04 am
The first noticeable thing is that both are displaying a bit of asymmetry. There is a falloff of corrections in the lower left corner of each image but in the second image it is worse. Something is out of alignment. How were these taken? It seems that you are capturing almost the entire image circle that the objective is capable of. The misalignment could be the objective being a bit off center.
Hmmm. There may well be some issues with the microscope that need to be addressed. I’m learning as I go, and the stand has quite a few years under its belt. I’ll continue to iron out the kinks as I discover them.
apochronaut wrote:
Tue Jun 02, 2020 10:04 am
To answer your exact question, though. Both show a bit of peripheral distortion, which is expected when you go to the extreme edge of a lens or lens system. The second image however, seems to have it worse, and also , maybe slightly worse contrast in general .
If I pick out specific details in what I would assume to be the area of the lens that would be used for framing. I would give the first image a higher score for contrast and resolution.
That’s pretty much the same conclusion I came to. In all honesty, I feel the difference is quite small and could be resolved during post processing. Still, the winner in this case is the 2X teleconverter. A tighter crop to eliminate the peripheral distortion would be ideal. Shame I don’t have a 1.7X converter. I’ll try my APS-C sensor on the 2X, and 1” sensor without the 2X.

Any suggestions for a better subject?

apochronaut
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Re: AO Triocular vs Beam Splitter

#39 Post by apochronaut » Tue Jun 02, 2020 2:28 pm

You shouldn't have to post process to remove lack of correction with a photo eyepiece. Coma and distortion shouldn't be part of the picture and can only be cropped out anyway.


I still would like to know the particulars of how you did that set up. I use a # 437/1054 focusing eyepiece all the time in the factory made trinocular tube and it provides corner to corner correction and sharpness covering close to the entire field ; at least with the corners of the frame at the field stop.

so , here are three characteristic images I took a few weeks ago, testing some phase objectives. Only one of these is a plan but the corners of the frame are right out to the field stop, so the field coverage compared to the visual eyepiece is maximum.

those are all 100X oil immersed, so the fine details are .5 micron or less.

apologies for the image choice; not the best , I should have found some at a lower magnification but these came to hand, easily. 100X oil photomicrographs are always difficult but the point is about the peripheral distortion. I don't see it with those eyepieces normally, and I have used quite a few of them.
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Zuul
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Re: AO Triocular vs Beam Splitter

#40 Post by Zuul » Tue Jun 02, 2020 3:41 pm

I didn’t note the particulars of the set up last night, so rather that guess, I reset the camera and shot a couple more. This time the spacer between the phototube and #437 was shorter, so the extremities have been cropped out. The distance from the trinoc shoulder the the top of the eyepiece is 155mm. From the eyepiece top to sensor plane is 92mm. (Measurements +/- 0.5mm) Objectives: 10X (1019) and 20X (1022) No effort to make parfocal (but it’s close). Focus by live view.

Image#437 10X Test by Mickey, on Flickr

Image#437 20X Test by Mickey, on Flickr

apochronaut
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Re: AO Triocular vs Beam Splitter

#41 Post by apochronaut » Tue Jun 02, 2020 5:28 pm

The 1019 is pretty good because those objectives are not quite plan and perfectly corrected to the periphery anyway, so the image capture is probably fairly accurate. Something is off with the 1022. That objective is perfectly plan, at least across 20mm anyway.

I have a question for something you can try. If you put the 437 into the side of the optical tube with the diopter, how does it work paired with a 176?

Zuul
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Re: AO Triocular vs Beam Splitter

#42 Post by Zuul » Tue Jun 02, 2020 8:05 pm

apochronaut wrote:
Tue Jun 02, 2020 5:28 pm
I have a question for something you can try. If you put the 437 into the side of the optical tube with the diopter, how does it work paired with a 176?
Aside from not being parfocal with the 176 (it’s wound to its lowest, and I didn’t try to match focus) it looks fine viewed by eye. I am surprised by how “deep” the ink is, though. The black is on an obviously different plane than the color ink, and there seems to be some separation I can’t explain. But I digress....

The only thing that was touched between viewings (both photos and by eye) was focus and rotating between objectives. Maybe there is something amiss with the nosepiece? It is a quint from a 110, but that in itself shouldn’t be a problem. I’ll try to troubleshoot more tonight when I get home from working at home. :D

apochronaut
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Re: AO Triocular vs Beam Splitter

#43 Post by apochronaut » Tue Jun 02, 2020 9:01 pm

The focusing eyepiece should be closely parfocal with the 176, it should be easily attainable to do so with the diopter and the view should not have anything noticeably deficient about it. If it isn't compatible; if it causes undue eyestrain, requiring a fairly large degree of diopter adjustment to get acceptable parfocus with a 176, then it is likely it has been taken apart for cleaning at some point and the bottom element has been reversed. Such eyepieces will focus and seem o.k. but not particularly well corrected; lacking planarity and with some peripheral distortion ; kind of like a Huygens used with a standard achromat but with a wider field. Old school W.F. eyepieces from the 40's were like that, before it became a reasonably priced option to offer w.f. plan eyepieces.
The eyepiece should be perfectly plan in the ocular tube and project a perfectly plan, full field image to the sensor, moderated only by the degree of planarity of the objective.

The bottom element is a doublet with a rather thick lower lens cemented to a thinner upper lens. The upper lens overhangs the edge of the lower one some, with the upper surface having a stronger convex curvature then the lower.

Zuul
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Re: AO Triocular vs Beam Splitter

#44 Post by Zuul » Wed Jun 03, 2020 1:11 am

I decided to put something interesting on the ‘scope for a change. Obviously, there are lots of things yet to learn.
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Zuul
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Re: AO Triocular vs Beam Splitter

#45 Post by Zuul » Wed Jun 03, 2020 1:45 am


apochronaut
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Re: AO Triocular vs Beam Splitter

#46 Post by apochronaut » Wed Jun 03, 2020 11:07 am

not knowing how much crop there is with these, based on the corner distortion in the earlier laser print images, I would verify whether the eyepiece is correctly intact but take a closer look at the 20X objective. Seems it may have something going on.

einman
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Re: AO Triocular vs Beam Splitter

#47 Post by einman » Thu Jun 04, 2020 1:36 am

Hmm..I don't recall any of the issues Apo referred to when commenting on some of the proposed set-ups I used. However- he tends to have a more precise eye. For example I will often comment about, but overlook the fact, the camera is not parfocal with the eyepieces as I generally have my camera tethered to my laptop and rarely use the eyepieces when stacking etc. I use a monitor. In any event he is the resident AO expert.

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