Zeiss Tessovar

[augusthouse]

Hi, I can't seem to find much info on the web regarding this guy - Zeiss Tessovar Photomacroscopy System.

Would anyone have a moment to briefly enlighten me on the benefits of owning one for studio macro work?

I did manage to find some info at The Macrolens Collection Database.

http://www.macrolenses.de/ao_detail.php?AdonsNr=213

I am currently using a Nikon D100 and PB6 bellows and have been building a stacking bench from old microscope parts and some other course and fine focus gizmos.

[DaveW]

Just done a search and these came up. Don't know if these are what you are talking about?

http://www.a1.nl/phomepag/markerink/tessovar.htm

http://www.users.globalnet.co.uk/~kevsm ... pment.html

http://cgi.ebay.com.au/Zeiss-Tessovar-p ... dZViewItem

http://www.microscopen-specialist.nl/fs ... scoop.html

DaveW

[augusthouse]

Thanks for input DaveW

Just wondering how this guy would perform on the end of the PB6 Bellows? If I wanted to extend its mag. capabilities....

The Zeiss Tessovar macrophotographic system has zoom capabilities using a total of three auxiliary lenses which allow a magnification range of 0.4X to 12.8X in total.

With the Polaroid attachment it can reach up 40x. What about a DSLR on the end of the PB6 bellows instead of the Polaroid attachment?? DOF and all things being considered.

I'm intrigued.

[DaveW]

Rik or somebody else will know, but I would have thought the camera on the end would make no difference. 1:1 is the same on any camera and the magnifications the same providing you are using the same extension.

I am unclear though if you were presently using a Polaroid camera on the PB6 bellows with the Tessovar attached? If so the only alteration in magnification I can see would be any difference in magnification caused by lens mount to film plane measurement in the two cameras?

I would have thought it would be altering the focal length of a lens on the front of bellows basically, not altering the camera on the back that would determine magnification, apart from any lens mount to film plane differences as said before? I don't know the equipment however.

DaveW

[rjlittlefield]

Hi, I can't seem to find much info on the web regarding this guy - Zeiss Tessovar Photomacroscopy System.

Would anyone have a moment to briefly enlighten me on the benefits of owning one for studio macro work?

I did manage to find some info at The Macrolens Collection Database.

http://www.macrolenses.de/ao_detail.php?AdonsNr=213

I am currently using a Nikon D100 and PB6 bellows and have been building a stacking bench from old microscope parts and some other course and fine focus gizmos.

I think the key word here is "System" -- Zeiss Tessovar Photomacroscopy System". I have never had hands on one of these things either. But judging from the photos at macrolenses.de ...

That system appears to includes:

• boom stand
• coarse focusing dovetail
• fine focusing dovetail
• nosepiece with one fixed objective, 3 external auxiliary lenses, and some internal optics for zooming
• 3 different camera attachments, each with its own additional optics

Because of the additional optics in each camera attachment, the System really does change the magnification for different film sizes. The maximum magnification of 40X, using the Polaroid adapter, is achieved by taking what would be a 35mm image at magnification 12.8X, and spreading it out over a larger area. If you replace the large Polaroid film sheet with a small sensor, it's likely that you will not reveal any more detail at 40X than at 12.8X, although the field of view will definitely be a lot smaller.

I'm not sure what would be involved in sticking the Tessovar optics on the end of a bellows, and I'm not sure why you would want to do that. I would guess that Zeiss optimized all the parts to play well together, to produce the best image possible on each of the film sizes that they support. It should work fine to use a slightly smaller DSLR sensor (e.g. Nikon D100) in place of film, on the 35mm adapter. The field size will shrink by a factor of 1.6, but the image quality should remain good.

I don't know what would happen if you fitted the Tessovar nosepiece by itself on the end of a bellows, dispensing entirely with the Tessovar's camera adapters. If you're lucky, and the Tessovar's 35mm adapter actually does not have any glass in it, then of course the image quality would remain high. If you're unlucky, and the Tessovar's adapters not only contain glass, but very special glass that performs the last bit of optical correction, then doing away with the adapter might not work so well.

The other question that crosses my mind is how much tradeoff in image quality Zeiss had to make, to pack such a wide range of magnifications (from 0.4X to 12.8X, for 35mm) into such a small package. Zeiss is good, but I cannot help being suspicious every time I hear the magic words "auxiliary lens".

As to DOF, that's determined entirely by the aperture and follows the usual tradeoff caused by diffraction: small aperture -- lots of DOF but low resolution; large aperture -- minimal DOF but potentially high resolution.

Since you're intending to stack, the most important feature of your lenses will be to have the highest possible resolution. For the Tessovar, Zeiss quotes NA of 0.110 at 12.8X. That is significantly less (less=worse) than the NA 0.25 that you could easily get from a 10X microscope objective. It's also less than the NA=0.16 that corresponds to an Olympus 38mm f/2.8 bellows macro lens (ref) used wide open at those same magnifications.

I know from personal testing that lenses in the Olympus bellows macro series are very good. Reversed primes and good enlarging or cine lenses can be almost as good and are much cheaper.

Bottom line, I'd have some reservations about sticking the Tessovar into your setup. It might work fine, but to my eye the other approaches should give equal or better quality images, and they have a lot less to go wrong.

Hope this helps -- let me know if I seem to have misunderstood or scrambled anything.

--Rik