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Short 100-200mm FL lenses with tripod collar?
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PostPosted: Sat Apr 02, 2022 4:19 pm    Post subject: Reply with quote
I think I have worked out what is going on (could be wrong though!)

I suspect that the reversed f/2.8 lens you are using is already the limiting stop. The light coming from the corners of the FOV entering through the small entrance pupil, will make it to the sensor just within the edge of the wide-open aperture of the main lens. When you stop down the main lens, you'll be cutting off those rays and you get vignetting in the corners.

I could be wrong (never done this myself) but I suspect your setup is just the opposite of the way it is supposed to work; with a stopped-down main lens and a fast (f/1.4 or so) reversed lens. Then the entrance pupil would be determined by the main lens rather than the reverse lens. Which is the opposite of what is stated in the website you listed, but in line with the other sources I have to hand.


PostPosted: Fri Apr 08, 2022 7:48 pm    Post subject: Reply with quote
eggplant wrote:


Just give me a short m42 extension tube with a tripod screw in it, etc.


Well, ask and you shall receive... It's not short enough/not necessarily comparable to the Leica example I gave, but worth a mention anyway:



There are plenty of 1:1 converters for lenses out there, but usually they come with optics, and only rarely with a tripod mount (e.g. for Vivitar 90mm). Well, this has the best combination: no optics and a tripod mount.
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