Orthoplan Photomicrography using KAVAR

[bill2penn]

I was able to get my new (used from eBay) Canon 6D camera attached to my long dormant Leitz KAVAR 35mm camera adapter by using a t-mount adapter. The KAVAR fits over the Orthoplan phototube at the top of which sits a GW 10X MF eyepiece. I did some measurements with my micrometer slide (200 divisions of 0.01mm each) to check how the field of view(FOV) looks in eyepieces on the scope versus the KAVAR and camera. If I used my 16X Plan Fluotar objective and the GW 10X eyepieces on the scope, the FOV measured 140 divisions. If I look through the eyepiece of the KAVAR or take a picture with the camera the FOV is 57 divisions. This is quite a difference. Interestingly (to me at least) if I replaced the phototube eyepiece with a GF 10X or "regular" periplan 10X eyepiece, the FOV is also 57 divisions. If I look through the Orthoplan head using these two eyepieces, the FOV is 107 and 84 divisions. So it looks like the KAVAR was designed for a "regular" Periplan.

Now if I exchange the phototube eyepiece with a GF 6.3X M eyepiece, the FOV is now 83 divisions. So that's what I'm using for now.

I also took a hand-held shot of the micrometer slide through the phototube with the GW 10X MF eyepiece using the Canon 6D with a 50mm F1.4 USM lens set to manual focus at infinity. The FOV was 90 divisions. So the question I have for the experts is, do you think (or does someone have experience with) that the Canon EF 40mm F2.8 STM pancake lens would give the full field of view? If so I might consider getting one but I then would have to rig up a way to adapt and steady the camera.

Some images below: KAVAR attached, shots of micrometer slide with GW 10X and GF 6.3X.
Bill

Edit: I labeled the images

[bill2penn]

Some further measurements. I used the 50mm F1.4 lens focused at infinity set as close as possible to the eyepiece (the UV filter resting on the eyepiece) to take images of the micrometer slide through the photoport with three different eyepieces. One was the GW 10X MF which measured the FOV of 90 divisions, next was the 6.3X M eyepiece which measured 107 divisions and finally I used my old eyepiece that had been attached to my Nikon 995, a Periplan GF 10X/20 eyeglass M (this is for 160mm tube length scopes so it needs refocused quite a bit) which had a FOV of 95 divisions.

Thanks for any insight.
Bill


Edit: Note that later in this discussion I removed the UV filter so that the lens could get closer to the eyepiece. This did not change the FOV of the 6.3X eyepiece but the GW 10X FOV now measured 107. Note that this is still far short of the 141 measurement if I look by eye, or I use my iphone camera.

[Pau]

Hi Bill,

I'm trying to understand your measurements but I find some uncertainties:
- What's the magnification of your nosepiece: 1X or 1.25X ?
- Whats the FN of your eyepieces ? Leitz made 18, 20, 24 and 28mm FN models, being the more usual 18 for 23.5mm tube and 24 and 28 for 30mm tube for 10X and lower eyepieces,
- Only some Plan Apo and Plan Fluotar objectives are able to fill 28FN eyepieces, do you know the FN of your 16X Plan Fluotar?

EDIT: All the following text now has little or no sense after the clarifications and modifications made by Bill so I make it barely readable, better just ignore it
(your data marked in blue)
I think that the nosepiece is 1.25X and the GW eyepiece FN28:
140x16 = 2240 22.40mmx1.25 = 28mm
If so, your 16X is delivering a 20X primary image (16x1.25 = 20)
In the two images taken with the KAVAR I can do the following calculation:
With a 20X objective and taking the long side of your sensor as 36mm you have:
36mm/20 = 1.8mm (= 180 divisions of your micrometer slide)
44mm sensor diagonal/36mm sensor long side = 1.22 factor
Image #1 (I assume that this is with the 6.3X)
82x1.22 = 100.04, about 1mm diagonal of sensor equivalent
180/100 = 1.8; 1.8X would be the KAVAR relay magnification, adequate for FF
Image #2 (I assume that this is with the 10X)
57x1.22 = 69.54
180/69.54 = 2.58; 2.58X would be the KAVAR relay magnification, still adequate for FF, close to the 2.5X standard although too cropped for my taste having a wide field microscope
If my former calculations are correct (of which I'm not sure at all ) and being the formula to calculate the relay magnification of afocal systems:
RM = (eyepiece magnification) X (camera lens FL) /250
Playing with the former calculated magnifications, we can get values of 64.5mm and 71.4mm for the KAVAR relay lens focal length (of course all data here are approximations)

[Pau]

I also took a hand-held shot of the micrometer slide through the phototube with the GW 10X MF eyepiece using the Canon 6D with a 50mm F1.4 USM lens set to manual focus at infinity. The FOV was 90 divisions. So the question I have for the experts is, do you think (or does someone have experience with) that the Canon EF 40mm F2.8 STM pancake lens would give the full field of view? If so I might consider getting one but I then would have to rig up a way to adapt and steady the camera.

I think that you have something limiting the FOV, at least with the 10X eyepieces IMO you would fill the sensor without vignette and in plus the periphery of the image field just at the limit of the Periplan eyepiece diaphragm would be sharp and showing an orangeish halo (typical of compensating eyepieces) if it was the limit.
The guilty can be the the camera lens and/or the phototube (I think that the KAVAR is designed for 23.5 eyepieces)
If you can fill the frame shooting through one of the visual eyepieces without vignette it's the phototube. You can also test shooting through the eyepieces with a phone camera : It will show vignette but showing the full visual field and the aforementioned sharp limit with halo, if the phototube is vignetting you will be able to see it this way.

The 50mm lens will provide 2X magnification with 10X eyepiece and only 1.26X with the 6.3X
The 40mm lens would provide 1.6X magnification with 10X eyepiece and only 1X with the 6.3X
In both cases you will get vignette with the 6.3X although maybe the 50X could be adequate if you crop the frame to a more square format

[bill2penn]

Hi Pau,

My nosepiece is 1.0X. I also have a 1.25X if you want me to try that.
I assume that the 30mm GW 10X eyepiece FN is 28 but I'm not certain. I also am not certain of the FN of the Pl Fluotar 16X but it's one of the newer 160mm tube length ones so I assume it's also 28.

The first image in my first post (40 - 90) is taken by KAVAR and the 10X eyepiece.
The second image in my first post (30 - 100) is taken by KAVAR and the 6.3X eyepiece.
Ignore the images in the second post since they suffer vignetting from the 50mm lens not being close enough.

I imaged through the eyepieces using my Iphone XR. One image is using the GW 10X eyepiece, the other the 6.3X eyepiece.

Do you think the Canon 40mm pancake lens will show the whole field?

Thanks for trying to help me understand this.
Bill

Edit: GW 10X eyepieces have FN of 24

[bill2penn]

And one more measurement and piece of information:

The GF 10X/20 high eyepoint eyepiece has a FOV of 114 divisions when I view through it with the binoc.

So using this piece of information the GW 10X would have a FN of 140/114 x 20 = 24.5

Oh, and one more thing. All the images in my second and third posts were taken through eyepieces that were in the binocular head so they show what I see through the scope.

Bill

Edit: I looked it up and the 30mm GW 10X eyepieces have a FN of 24
GW 8X and GW 6.3X have a FN of 28

[Pau]

My nosepiece is 1.0X. I also have a 1.25X if you want me to try that.

If you used the 1.0X my calculation must be wrong, although I don't see why

I assume that the 30mm GW 10X eyepiece FN is 28 but I'm not certain. I also am not certain of the FN of the Pl Fluotar 16X but it's one of the newer 160mm tube length ones so I assume it's also 28.

Yes, AFAIK 160 Pl Fluotars are FN28

(paragraph removed because Bill's correction on original post)

Ignore the images in the second post since they suffer vignetting from the 50mm lens not being close enough.

So, you think that the camera lens is the vignette cause, do you?

I imaged through the eyepieces using my Iphone XR. One image is using the GW 10X eyepiece, the other the 6.3X eyepiece.

Did you it with the eyepiece at the phototube or at the visual ones? In the second case please repeat the test on the phototube.
It seems that the 6.3X has smaller FN than the 10X

Do you think the Canon 40mm pancake lens will show the whole field?

(More than the whole field the maximum rectangle covering it)
If the phototube doesn't vignette I think so with the GW10X: 28x1.6 = 44.8 , an almost perfect match for the FF sensor diagonal
I use a Olympus Zuiko 50/1.8 and a now also a SMC Pentax K 40/2.8 pancake and both are very convenient for afocal. The Canon likely is better optically but mechanically much less solid

[bill2penn]

I took off the UV filter so I could get closer to the eyepiece. With both the GW 10X and GF 6.3X eyepiece and my 50mm lens, I see 107 divisions! Images below.

When I use my Iphone to take images through the eyepieces in the phototube (and of course the KAVAR is removed) I see the same as through the eyepieces of the binocular head. I get 141 divisions for the GW 10X eyepiece and 107 divisions for the 6.3X eyepiece.

edit: I replaced the original images with images with titles so they are easy to know what they are.

[Pau]

Thanks for the corrections of text and images, now most aspects look clearer.

Some of my former points aren't now valid, I would need to redo most my calculations although right now I don't have the time for doing it, so I just comment some relevant points:

- The vignette with the 50mm /1.4 is due to the camera lens, its diaphragm plane seems to be too recessed for the eyepoint of the eyepiece. A smaller lens like the ones I use would avoid lens vignette producing adequate coverage.
If your GW 10X has FN 24 now I don't think that a 40mm camera lens could completely avoid vignette
at https://sensorsizes.com/ you have an useful tool; select EOS R5C (photo) to have FF sensor and your eyepiece FN x afocal magnification in your case 24x2=48, just a bit larger than the 43.27mm FF diagonal, but 24x1.6=38.4 with a 40mm lens, smaller than needed (although still useful if you want to crop to a more square format profiting a some more microscope field)

- Based in your phone pictures your GW 6.3 must have smaller FN cause the field with the image is of 1.06mm vs 1.40 of the 10X, doing the proportion it is 18 (18.17), so useful with the KAVAR but not with the 50mm camera lens

[bill2penn]

Hi Pau,
Thanks for the info.

My 6.3X is not GW. It is a 23.2mm eyepiece and probably a GF (FN18) although there is no writing on the eyepiece other than 6.3X M

Bill

[Perl]

there are Periplan 10X GW with 26 FOV

[bill2penn]

there are Periplan 10X GW with 26 FOV

But I believe those are 160mm tube length.

[bill2penn]

This is a followup from my previous post (viewtopic.php?p=287882#p287882)

So after seeing Alex's set up (viewtopic.php?p=287881#p287881) I decided to have another go at positioning my camera on my Orthoplan. I ended up using a ring stand with clamps to hold my tripod upside down. Not pretty but it did allow me to do some more testing using the Charles Krebs projection method. I focused the slide using the eyepieces and my glasses, then after making sure the eyepiece in the phototube also had a focused image I raised the eyepiece by about 8 mm. Then I positioned my camera without lens above it and centered it as well as I could with this apparatus. Using Canon Liveview I raised/lowered the camera until I had the best focus. This distance was about 30mm from the camera flange to the top of the eyepiece. I was able to get a good sized field of view of about 90 divisions on my micrometer slide scale. Through the GW10X eyepieces I get 141 divisions so this is a pretty good field of view. I then took some shots of diatoms to see how well it works.

So now I have to find a better way to attach my camera and get a bellows as a hood for the unit. But I think a variation of this is what I will settle on.

[bill2penn]

And as a preview of what I hope to eventually implement, I have the optical guts of an Orthomat-W coming via post from Europe. This unit can "zoom" 2X, 2.5X and 3.2X by a twist of the bottom ring. At 2X it supposedly has a field number (FN) of 22. So this would be able to image a large amount of the field of view that I can see with the GW 10X eyepieces. According to the Leitz literature in a previous post, I think that I will need to place the sensor of my camera 83.3mm away from the top of the lens on this unit (http://www.science-info.net/docs/leitz/ ... -15-64.pdf) and it should work just like the original 35mm camera.
Stay tuned!

[Perl]

The GW 10X 26 FOV Periplan are not specified to any special tubelength
Regards
Pär