Polylite SC endusers(?)

[apochronaut]

I did fo a quick measure on one of my infinity 7 1/16"/182mm systems and with the 19mm f.n. photo eyepiece sitting parfocal in the 182mm rube, my APS-C 23.5mm sensor sits 58mm above the top of the eyelens.
You are projecting a 24mm field to a sensor very close to the same size, so you are going to have to get 15mm or thereabouts closer to the photo lens in order to optimize the field to frame coverage, assuming you want to photograph what you see. That's why the helical focuser is a good tube to use. You can do on the fly framing. Any way of trying an approx. 40mm lens to sensor distance? The helical focuser I use is 15mm closed and 31 extended , M42 to M42 thread. The eyelens end end of your WPK eyepieces, that 15mm diopter, will go inside the helical focuser but the main body won't. There is a 25-55mm version.
https://www.ebay.com/itm/285489095158?i ... R9SN2fzDYw. Also some 11/4" telescope versions.
The WPK eyepieces by the way are completely neutral eyepieces but probably do some field flattening, hence the PK.

[JWW]

If you can set the shoulder of your eyepiece at 7 1/8" ( not the surface of the top lens) you would get parfocalization and then be able to adjust your sensor distance for a preferred field. Installing a helical focuser on the camera side is a useful idea to refine focus but also to allow for some framing and cropping options.

I'm printing a bunch of stuff right now. I'll print something up to get the 7 1/8" measurement you suggested tonight or tomorrow. It depends one when the other things are done printing. Once everything is figured out, I'll incorporate a helical focuser into the configuration.

Thanks,
-JW:

[JWW]

Any way of trying an approx. 40mm lens to sensor distance?

I don't understand the question? Do you mean sensor plane to eyepiece? The Canon 50D is 44mm from the sensor plane to the flange on the front of the camera.

-JW:

[JWW]

If you can set the shoulder of your eyepiece at 7 1/8" ( not the surface of the top lens) ......

I just want to clarify the dimension, from where to where, before I draw up something to 3D print, please.

-JW:

[apochronaut]

I was wondering about the depth of that big camera. I thought maybe 20mm. Mirrorless are a lot less : 15mm or so. With the 10X eyepiece you will have to use a shallow Canon bayonet to M42 female and the shallowest helical focuser of that type which is 12mm to 17mm or something in that range. It would have to thread onto an M42 male stub that surrounded the eyepiece diopter. It's compact and doable as long as the camera body can be lowered slightly over the eyepiece diopter for framing.

With the 6.3X eyepiece it works out much closer dimensionally to my 19mm f.n. system and a 10X eyepiece. You would want a roughly 55mm distance. If you incorporated a helical with a short range might be better. Your camera is heavy and the less flex the better. My mirrorless is light. They have a 10-17mm version I think it is. The helical should be as low as possible since it isn't too much bigger than the eyepiece diopter. I doubt if vignetting is an issue. There may be other helicoids you like better.
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On your sketch the 182mm measurement is from the lens situated in the trinocular dovetail at the top of the microscope body to the eyepiece shoulder or flange. The Wild 40/14 piece is just a 30mm collar to receive the eyepiece correct? No optic in there?

The actual measurement is probably 182mm and change. I read somewhere that it was 182. 5 once but I can't be sure. AO was using this measurement going back to 1956 or so and maybe even earlier. I am not sure what the reference length was on their Met microscope beginning in the late 40's : the Apergon. It was infinity. AO was a company that almost always used inches, so if you convert 182.5 over, it comes out almost exactly to 7 3/16". They started using that with the series 4, then it became the standard for all the subsequent infinity systems they refined , right into the Leica era. When Reichert, which AO had already owned for 8 years , introduced their infinity system they used the same reference length. It eventually became known in a rounded off metric measure but probably began as an inch measure.
I can try to measure a straight through photo tube as accurately as possible. I don't have a caliper that long but will try.

[JWW]

What should the measurement be from the eyepiece shoulder to the flange on a 50D?

What camera are you using? I don't recall.

-JW:

[wabutter]

I don't know if it is the same, but likely is. the distance with a C'mount is 11mm.

[apochronaut]

What should the measurement be from the eyepiece shoulder to the flange on a 50D?

What camera are you using? I don't recall.

-JW:

Eyepieces are all different in height from their mounting shoulder to the eyelens or projection surface, so I don't use the eyepiece shoulder as the beginning point for the second important linear measurement. I use the eyelens surface to sensor. My camera is a Sony A5000, with a sensor about 5% larger than yours. The math is a little difficult to be dead certain on becsuse of the sensor diagonal difference plus the f.o.v. difference between our two systems. You also may use a different aspect ratio, than the 16 x 9 I usually use. Assuming you are looking to have the visual microscope f.o.v. just outside the sensor diagonal, then the eyelens to sensor difference will be in the mid. 40mm distance for your system, adjustable + or - with a helicoid.
Factoring in those differences in sensor size and f.o.v. means that your image circle at any given distance is about 30% larger than that on my working system, so you need to either shorten the distance from the eyepiece to sensor in comparison to my syetem or use an eyepiece with a correspondingly larger real field coverage , the 6.3X.

Wayne Butter mentions 11mm for a CCD camera. Maybe that was the sensor diagonal used originally? Could even be the distance because I did see that old picture of a Poly something with the ccd camera right on top of the lens.

[apochronaut]

If I was doing it, I would make a mock up out of cardboard tubing, ABS pipe, sonotube, or something similar to see what the projection comes out like first. A packing tape roll is 48m and wide enough to avoid vignetting and a toilet paper tube might be at the narrower end of the spectrum.

[JWW]

I don't know if it is the same, but likely is. the distance with a C'mount is 11mm.

Thanks Wayne.

-JW:

[JWW]

Not that anyone cares. I finally have both the Polyvar MET and Polylite SC configured for a DSLR (APS-C ). Each configuration was a little different for each scope. All parts on the MET were 3D printed. The 3D printed components are not as ridged as matching them would be, but they work. I wish I had the original controller, but they seem to be unobtainable. It would be sweet to have the motorized turret working on both scopes. I have a friend who has two 100% complete Polyvar SC's. Anyway, I'm happy with the current configurations. I've also included a test shot with the MET, but there is no stacking.

-JW:

[Scarodactyl]

Congratulations! Looks like you're getting good shots.

[apochronaut]

I am interested in knowing what the field capture is and what measurements you used . Telan lens to eyepiece and eyepiece to sensor
The test shot looks good.

[JWW]

There is a big difference between the image viewed through the binos and captured by the camera setup. The MET came with WPK 10x eyepieces installed in the bino head. The MET and SC are different. The MET doesn't have a lens in the top plate as does the Polylite SC. The MET was set up for a film camera. I removed all those components and tossed them. I machined a new top replacement cover plate for the MET. I bored a hole in the appropriate place. So, to be clear, there isn't a Telan lens in the MET. The measurements for the MET are approximately 132mm from the top plate I machined to the top of the WPK 6.3 eyepiece and 120mm from the top of the eyepiece to the 50D sensor.

On the Polylite SC, it's 150mm from the Telan lens to the top of the WPK 6.3 eyepiece. I don't recall what the measurement was from the top of the eyepiece to the sensor on the SC.

This is another test shot, with a 50/0.85 IK. My cell phone was just held up to the eyepiece.

-JW:

[JWW]

Just another test. Here's a single-shot image taken with the MET and SC. I used the exact same objective (20x0.40 IK) in each. I removed it from one of the scopes and placed it into the other scope. It's the same wafer but in a different area. The SC has that Telan lens (?) in the top. As you know, that lens doesn't exist in the MET. Both scopes are using a WPK 6.3 relay. The filename will tell you which scope is which.

[apochronaut]

So the telan lens is not contributing any corrections for ca or likely sa either. It is just a convergence lens. The eyepieces that I have from some Poly microscope, I just today pictured in your other thread , seem to have some correction for curvature of field. They have a fairly pronounced concave eyelens, similar in fact to the AO #145, which works equally well with the Reichert Austria objectives, while the array of other AO eyepieces yield varying degrees of mostly curvature but some ca too.
Probably without the eyepiece in the photo tube, you would have curvature. Did you attempt to directly project?

[JWW]

The very first thing I tried with both scopes was a direct project approach. That was at least three years ago. All I really know is it didn't work. I also had some pincushion going on, but I also don't remember what the setup was that caused it. The attached image is from yesterday, taken with the SC. To me it appears something is going on with this image. Just a single shot. The lower right hand corner seems skewed but then again I have vision issues in my old age.

-JW:

[apochronaut]

It looks like it might be decentered to the right some plus some pincushion curvature. The brown line that runs top to bottom on the left side is slightly bowed in and there is some ca bordering the characters to it's left.

[JWW]

I should have done a better job centering and rotating the actual image. Oh well. Here's a screen capture with a grid.

-JW:

[JWW]

A few test images with the Polylte SC. I should have added a few more photos to the stack for complete focus. Oh'well. This is a Calcite sliver photographed with my Polylite SC. It's the same stuff Wollaston Birefringent prisms were made out of and used in a Polarimeter to measure magnetic fields via a solar telescope, Differential Interference Contrast (DIC) microscopy, and other uses. I am happy with the results.

-JW: