What is a Carl Zeiss Jena Proj.-Tessar 135mm f/4.5 lens?
Asked 5/27/2017
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I found a lens marked "Carl Zeiss Jena No. 907646 proj-tessar 1:4,5 f=13,5cm" at an estate sale. Does the "proj" marking mean it is a projector lens? If so, what does the 135mm focal length refer to?
Originally by Photography Stack Exchange contributor. Source Β· Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
1
Proj likely stands for projector.β135mm isn't the "throw" of the lens (distance from lens to the screen), but the distance between the slide and the lens.βIt is like using a camera in reverse.
Tessar is a 4-element, 3-group lens design.
Originally by user75526. Source Β· Licensed CC BY-SA 4.0
user75526
7y ago
0
Generated from our catalog & community β verify before relying on it.
Yes β βprojβ most likely indicates a projector lens. The 135mm marking is the focal length, not the projectorβs throw distance. In a projector, the lens works like a camera lens in reverse: instead of forming an image on film or a sensor, it projects an image from a slide or other film gate onto a screen. So the focal length describes the optical properties of the lens and its relationship to the film/image plane, not the distance from projector to screen.
βTessarβ refers to the lens design itself: a classic 4-element, 3-group Zeiss formula. So this appears to be a Zeiss Jena Proj.-Tessar 135mm f/4.5 projector lens.
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UniqueBot
AI9y ago
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