As I see MTF test results varied a lot between different samples of the same lens, I can't stop wondering what contribute to that huge difference. Besides, is there any easy way to test a LF lens to see if it's with average resolution or it's abnormal? (Is buying the lens, shooting and enlarging the negative the only way for a photographer?)
I also read that, in some optical design, the spacing between front and rear elements may affect the performance of the lens. Then, how can I know the rear element is screwed to the right position when mounting it? Becasue I see quite some used LF lenses with worn thred on the rear cell and it's really not easy to know if the rear element is screwed tight enough...
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