Making camera tube on Reichert Zetopan parfocal

[brettpim]

I have a Reichert Zetopan that I am getting ready for use. I have noticed that the photo tube is not parfocal with the oculars. This has been noted by Ian Walker and, like Ian, I find that it is worse for lower magnification objectives. What I have found is that if I raise the photo tube ocular by about 5mm then it is parfocal across different magnifications. My photo set up will be afocal using a Pentax 40mm pancake lens on my DSLR (although I am also working on duplicating the original Reichert camera system with my DSLR. I have all the parts except the Remica 35mm camera)

• Is the non-parfocalness simply a function of the effective tube length and the camera tube length is just shorter by 5mm? If so, why did Reichert make the tube length this much shorter?
• If I raise the camera tube ocular by 5mm, will this seriously interfere with the compensating function of the ocular?
• Is there any other reason I should not do this?

[Pau]

In principle the right position is the one where you get parfocality, so I would go ahead adding 5mm to the TL.

If the visual eyepieces are parfocal when changing objectives and the phototube eyepiece also is when raised you're OK almost for sure.

If the tube length is not right the main concern is not compensation but spherical aberration with high NA objectives plus the lack of parfocality with low magnification ones you've detected

Another thig is the cause, this could be due to the desing: lack of an adapter, regulation...I can't say, I have not experience with Zetopans

[Scarodactyl]

Was the zetoplan supposed to be used with a viewing eyepiece in this position, or did they possibly have dedicated photo optics?

[Pau]

Was the zetoplan supposed to be used with a viewing eyepiece in this position, or did they possibly have dedicated photo optics?

According with the parts catalogue available at http://www.science-info.net/docs/reichert/ it seems to use PK visual type compensating eyepieces.


brettpim, are you using original objectives and eyepieces?
I ask it because compensation can differ between makers and models and tube lenght also can (for example, I use Leitz Periplan eyepieces for 170mm system in a Zeiss 160mm stand and to work as designed they need to be raised 8mm)

[brettpim]

Thank you both for your replies.

brettpim, are you using original objectives and eyepieces?

My objectives and oculars are all Reichert and from Zetopan microscopes. They seem to correspond well with the parts I see listed (and some pictured) in the Reichert Zetopan catalog and price list.

Was the zetoplan supposed to be used with a viewing eyepiece in this position, or did they possibly have dedicated photo optics?

Another thig is the cause, this could be due to the desing: lack of an adapter, regulation...I can't say, I have not experience with Zetopans

I have been studying the documentation on Reichert's photography system and the parts I have to understand exactly how it works. I have parts 9 18 63 21 ("Beam splitter casing"), 9 18 63 25 ("Adapter ring"), 9 95 00 07 ("lens flange") shown on pp. 20,21 of Reichert Zetopan catalog and price list. The beam splitter casing only has optical elements for the viewing ocular and when image is directed towards camera it is simply an empty tube with a shutter mechanism. It is designed to clamp to a 35mm tube and is fitted to different eyepiece tube sizes with adapter rings. The lens flange is a 0.5x lens which mounted to a 35mm camera body that Reichert sold. I have found instructions for its use with both a steromicroscope and with the Zetopan. Both instructions indicate that the adapter ring is placed over the tube and the ocular replaced which puts the ocular at the same height as it would have been. In the stereomicroscope instructions this is the viewing tube itself, not a dedicated phototube and the ocular being referred to seems to be the viewing ocular. Then the beam splitter casing is attached over the adapter ring and ocular. Then the camera with attached 0.5x lens is fitted to the beam splitter casing. From length measurements I have made of the 0.5x lens flange I have and measuring lengths in images of the lens flange and Remica camera in various manuals and the catalog, I have a 10mm range of distances that the 0.5x lens flange should be from a camera sensor/film plane. With my m38 and m42 adapter rings I can get within this range attaching the 0.5x lens flange to my DSLR and it looks as if this is around the appropriate distance to focus an object at infinity to the sensor/film plane. I have ordered a helicoid M42 adapter so I will be able to test the entire 10mm range of positions for the 0.5x lens away from my camera sensor. Hopefully I will be able to solidify this assertion once I can do those experiments.

All this makes me believe that the Reichert photography setup was essentially afocal and leads me to think that the phototube on the Reichert was simply not parfocal with the viewing tubes. But I am not absolutely sure.

[Smokedaddy]

Just in case you don't have this, I copied it.

https://pbase.com/smokedaddy/zetopan

-JW:

[brettpim]

Just in case you don't have this, I copied it.

https://pbase.com/smokedaddy/zetopan

-JW:

Thanks Smokedaddy, I did not have those. Do you have the whole document that they come from?

[Smokedaddy]

Sure, I'll scan the booklet. There aren't that many pages. PM me with your email.

[Smokedaddy]

Thanks Smokedaddy, I did not have those. Do you have the whole document that they come from?

Here's the entire manual.

https://pbase.com/smokedaddy/zetopan&page=all

-JW:

[brettpim]

Here's the entire manual.

https://pbase.com/smokedaddy/zetopan&page=all

-JW:

Thanks. It covers a lot of the same information as the manual at the science-info repository but the camera info is new to me.
brett