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Optics Theory - This forum is aimed towards the TECHNICAL side of photographic OPTICS THEORY. There will be some overlap by camera/manufacturer, but this forum is for the heavy duty tech discussions. This is NOT the place to discuss a specific lens or lens line, do that in the appropriate forum. This is the forum to discuss optics or lenses in general, to learn about the tech behind the lenses and images. IF you have a question about a specific lens, post it in the forum about that type of camera, NOT HERE.

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Old 07-26-2017   #41
Calzone
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I forgot about my chrome 65/3.5 Elmar, a Visoflex lens with macro capabilities.

There are reports of mounting this lens on 645 cameras because it has a large image circle. I use mine on a black 1975 SL2-MOT with a Leica Viso to R-mount adapter.

This lens has no click stops for the aperture, but features a stop that can be set to swing from wide open to your selected setting easily. It only uses the "sweet spot" of the large image circle for edge-to-edge illumination and sharpness so it is kinda highly corrected, but a single coated lens. The macro function is great on a SLR.

Cal
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Old 10-21-2017   #42
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One way to be sure you have a Tessar is if it says' "Carl Zeiss Tessar" on the retaining ring (or someplace on it). I consider a "Tessar type" lens to of the traditional two elements, one positive and one negative, in front of the diaphragm and one cemented doublet in the rear, like the drawing Chris Crawford showed.
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Old 10-21-2017   #43
someonenameddavid
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Quote:
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Pan F,

Thanks for the correction.

Cal

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Old 08-06-2018   #44
JPD
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There was a five element/four groups 2,8/50 and 2,8/75 Xenar by Schneider. It's a Tessar type, but with the front element split in two to allow for better corrections. On the pre-war Kodak Retina II and IIa it was called "Xenon". It's sharper than the four element 2,8/50 Xenar used on the post-war Retinas, but has lower contrast due to being uncoated.



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Old 08-06-2018   #45
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At that point Xenar was a trade name there are 3 Element Xenars and five element Xenars the majority are tessar type lenses but not all. Ross also made a five element tessar to circumvent the Zeiss Patent.
The Ross X-press is a more than decent Tessar type lens.
Pre war Hugo Meyer Primotars are also good lenses.
A previous poster mentioned the 4/4 Dialyte type lenses they are actually often superior to tessars they have a wider image circle and are very well corrected. The drawback was less contrast due to more air to glass surfaces but a modern coated dialyte design gives more complicated designs a run for their money. The faster doppel Anastigmats that are found on plate cameras are usually dialytes.
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Old 08-07-2018   #46
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Quote:
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A previous poster mentioned the 4/4 Dialyte type lenses they are actually often superior to tessars they have a wider image circle and are very well corrected. The drawback was less contrast due to more air to glass surfaces but a modern coated dialyte design gives more complicated designs a run for their money. The faster doppel Anastigmats that are found on plate cameras are usually dialytes.

Indeed. I'm using a 6,3/135 Goerz Dogmar, which is a dialyte, and it's razor sharp, while the 4,5/135 Tessar is only decent. I have mounted a 4,5/135 Dogmar on another plate camera, that I will try, and have a fast Eurynar 3,5/150 (another dialyte) on another. I suspect that the 6,3 is the best one, but the shallow depth of field with the 3,5 Eurynar fully open could be nice.



Dialytes are interesting lenses and less commonly used than the Tessar types today by classic camera shooters. With the lens hood on and sun in the back, and using black-and-white film, a good dialyte can be excellent.


The slow 6,3 Tessar is said to be the sharpest version, but I haven't tried one yet, and not sure if I will. I have used enough Tessars.
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