Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

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bill2penn
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Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

This thread is a continuation of my efforts to obtain a wide-field digital imaging solution for my Leitz Orthoplan by using an Orthomat-W optical tube and a Canon digital camera. While at the point of this writing I am not completely finished with my conversion, I am happy with the progress. I also think I have learned the lessons to make it a good conversion. My previous efforts leading up to this point can be seen in this thread here: viewtopic.php?f=15&t=45778

There were at least two different Orthomat systems. The original one has a fixed 3.2X lens, and the Orthomat-W has a zoom system with 2.0X, 2.5X, and 3.2X stops. At 3.2X the field-of-view index is 14, for 2.5X it is 17 and for 2.0X it is 22. I wanted the greatest field of view so I got the Orthomat-W. However everything in this thread should be equally applicable to the older Orthomat except it would have a smaller field of view. For easy access I have uploaded the original Leitz literature on the Orthomat and Orthomat-W on the groups.io Microscopy site here: https://groups.io/g/Microscope/files/Or ... structions

There are a number of previous posts on the board with similar ambitions of using the optical guts of an Orthomat-W but none appeared to end with a satisfactory result, at least one that was documented in the threads. Some of these efforts can be seen at: viewtopic.php?p=278457#p278457 and viewtopic.php?p=51793#p51793 and others.

I wanted to document my efforts in this area so others could use my experience if they also wanted to use an Orthomat. If you look on eBay, Orthomat cameras can be obtained for $50 or less including shipping. Orthomat-W for just a little more. The optics in these units are first rate. My plan is simple: set up a system with the Orthomat-W optical tube that will place the full frame sensor of a modern digital camera at EXACTLY the same distance from the top of the optical tube as the film plane of the original camera. This should give exactly the same image as that of the original Orthomat-W with it's 35mm film camera.

I was able to obtain the optical tube assembly of an Orthomat-W from a friend in Netherlands. He was the one who dismantled it and cut wires, etc so I'm unable to comment on the disassembly process but others on this board have done similar. In addition to the optical tube, my friend also sent me the camera, film magazine, and shims so I could determine the distance from the top of the optical tube to the 35mm film plane.

With the film cartridge installed and the window opened I could measure the distance from the camera/optical tube interface to the film plane. It measures 32.75mm. So that's how far the full frame sensor of a digital camera needs to be from the top of the tube to get the same image view as the Orthomat 35mm camera. I have recently purchased a Canon 6D camera which has a flange to sensor distance of 44mm. So that's 11.25 mm too far assuming I don't add any kind of coupling unit onto the tube. Does this longer distance make a big difference? We'll soon see.
Attachments
cameradistance.jpeg
Last edited by bill2penn on Sun Mar 19, 2023 6:34 pm, edited 2 times in total.

bill2penn
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Location: Philadelphia, PA

Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

The optical tube that I obtained still had the electronic shutter assembly installed so no light could get through. But you can remove the top lens assembly and pull out the baffle to access the shutter. The shutter is removed with 4 screws. I tried to reinstall the baffle but it slid down too far because the shutter was no longer there to act as a stop. So I removed the two small swinging shutter leaves by ripping them out with needlenose pliers and then reinstalled the shutter assembly. The baffle fit in correctly now and with the shutter always open, light could get out the tube. The optical tube still has a couple holes in it that were used to divert some light to the Orthomat light sensor but I went ahead and used it as is for testing.
Attachments
shutter.jpg
tube-top.jpg

bill2penn
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

Now I can test out the consequences of having too long a distance from the tube to the sensor. To do this I fashioned a couple "viewers" out of a toilet paper roll. One I measured and cut at 32.5mm and the other at 44.0mm. Then I covered each with lens paper to act as a visualization screen. The diameter of the roll is about 38 mm so it will be larger than the 35mm film (24x36mm).
IMG_6290AB.jpg
I set up my scope with a micrometer scale slide. With the 16X objective I could see 140 divisions (1.40mm) in the field of view when using GW 10 eyepieces which have a field of view of 24. I focused wearing my eyeglasses so it would be focused at infinity. Then I placed the shorter viewer on top of the optical tube set at 2X zoom so that it would be at the same position as the 35mm film in the Orthomat camera. The image was in almost perfect focus on the tissue paper (as it should be to be parfocal) and measured 110 divisions.
IMG_6283AB.jpg
Then I replaced the viewer with the longer 44mm version. Now the image needed refocused to become sharp. Not a lot of refocus but enough. The projected image showed 92 division.
IMG_6284AB.jpg
Last edited by bill2penn on Sun Mar 19, 2023 7:07 am, edited 1 time in total.

bill2penn
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Location: Philadelphia, PA

Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

To "mount" my Canon 6D on top of the Orthomat tube I simply placed it on top of the tube. The camera was remarkably steady by just sitting on top. I couldn't quite center it because the retractable pin that hooks into the attached lenses pushed the camera up a little. Instead I chose to have the pin outside the tube so that meant that the camera was not quite centered.
IMG_6286AB.jpg
IMG_6285AB.jpg
I took an image of my micrometer slide and it had 87 divisions.
IMG_0560AB.jpg
Last edited by bill2penn on Sun Mar 19, 2023 7:44 am, edited 2 times in total.

bill2penn
Posts: 29
Joined: Mon Jan 02, 2023 2:42 pm
Location: Philadelphia, PA

Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

I took an image of a large diatom arrangement prepared by the late Klaus Kemp. This was taken using a Leitz NPL Fluotar 6.3X 0.20 objective and the 2X zoom position of the Orthomat tube. This is a single image (no stacking or stitching) and no postprocessing other than scaling it to 1024 pixels for the board.
IMG_0562AA.jpeg
As an added cool feature of this Orthomat tube, the sensor port acts as a projection system. When the system is focused for the eyepieces (or the 32 mm sensor distance), the image on the wall is also focused! Cool.
IMG_6293AB.jpg
IMG_6287AB.jpg

bill2penn
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Location: Philadelphia, PA

Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

So that's about where I am with this project right now. I can get a field of view index of about 17 using my Canon 6D just sitting on top of the tube. To get the full field of view index of 22 will require a camera sensor to be 12mm closer than mine (44mm). So someday I may get a mirrorless Canon camera that has a frame to sensor distance of 20mm. That combined with an adapter to mount on top of the Orthoplan tube should make an almost perfect match. But I am quite happy with what it does currently.

bill2penn
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

One more piece of data: I added a t-adapter to my Canon 6D to see how additional distance effects the image. This added 10mm distance so the total flange to sensor distance is now 54mm. I could place this on top of the Orthomat tube just like before. An image of the micrometer scale using the same setup as before gave an image of the micrometer with 77 divisions.
IMG_0575AB.jpeg

Pau
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by Pau »

This is a very nice piece of equipment and your results very promising.

Despite the results can be good with partially well tuned setup, the key to have it right is the parfocality:
- parfocality when changing objectives (only little refocusing needed)
- parfocality between the eyepiece visual image and the camera image (once corrected the eyesight if needed)
- In this case also parfocality when changing the Orthomat zoom magnification (here not 100% sure but almost)

So, yes, a mirrorless FF is the best option.
The diameter of the roll is about 38 mm so it will be larger than the 35mm film (24x36mm).
In fact the diagonal of 24x36 film and full frame sensors is about 43.3mm, a bit larger
Pau

bill2penn
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

Pau wrote:
Sun Mar 19, 2023 12:17 pm
This is a very nice piece of equipment and your results very promising.

Despite the results can be good with partially well tuned setup, the key to have it right is the parfocality:
- parfocality when changing objectives (only little refocusing needed)
- parfocality between the eyepiece visual image and the camera image (once corrected the eyesight if needed)
- In this case also parfocality when changing the Orthomat zoom magnification (here not 100% sure but almost)

So, yes, a mirrorless FF is the best option.
The diameter of the roll is about 38 mm so it will be larger than the 35mm film (24x36mm).
In fact the diagonal of 24x36 film and full frame sensors is about 43.3mm, a bit larger
Yes, of course, I always forget about the diagonal of the rectangle versus the diameter of the circle.

I checked the diameter of the image at 32.75mm above the tube end. It is 51mm so that will easily fully fill the frame. In fact the micrometer scale can be seen in the projected image as 150 divisions (vs the 140 in the eyepieces). Also it can be seen projected on the wall.

Bill

bill2penn
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

When the GW 10X adjustable eyepieces are completely screwed in I get a parfocal focused image in the eyepieces and at the 32.75mm viewing screen as one would expect.
Now when I focus the image on my Canon 6D camera (44mm distance) I need to refocus slightly. If I now adjust the eyepieces to get a good focus, the adjustments are only 2.7 to 3 mm extension of the eyepieces which is not a lot. With this eyepiece extension the eyepieces and the Canon 6D are now parfocal from 6.3X to 40X (all that I tried). So this is a very useful adaptation. The only "drawback" is that the field of view is "only" 16.8. But if I didn't know it could be 22 using a mirrorless camera, I would be an extremely happy camper with a field of view of 16.8!

Bill

bill2penn
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by bill2penn »

Kittonia elaborata image generated with Picolay using 16 stacked images. Taken on Leitz Orthoplan with a Canon 6D through Orthomat-W optics using Leitz Pl Apo 40x/0.75 160mm tl objective. Of course I had to reduce the size of the image to have it accepted by the board.
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k-elaborata-A900.jpg

Pau
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by Pau »

This is a great picture of a most nice subject
=D>
Pau

Scarodactyl
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by Scarodactyl »

Great image, and very clean too! Looks like you've got a great setup!

Beatsy
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by Beatsy »

Great image from a desirable homebrew setup. You can clearly see the 3d nature, even without a stereo. Very nicely done.

KI4THC
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Re: Using an Orthomat-W optical tube as a wide-field digital camera adapter for Orthoplan

Post by KI4THC »

Bill...I'm headed in a similar direction with the same basic equipment as you know. Right now I'm using a coupler from Bunton that works really well with the Canon, but we're going to pull the optical core from the Orthomat W and use that to fully replace the existing coupler. And that will connect to the Canon adapter. It should be able to Zoom I think.
Really nice work on your part!

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