Testing sharpness of adapted 24x36 SLR lenses

Started Sep 20, 2017 | Discussions thread
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Belgarchi Senior Member • Posts: 1,252
Testing sharpness of adapted 24x36 SLR lenses

What camera to use? Here is my point of view on 5 typical mirrorless cameras, covering 90+% of the market.

I don't pretend that this is an absolute truth, it is only my opinion based on my experience and logic, to help inexperienced people wanting to test lenses. My comments on areas and MP are approximations.

All opinions welcome, of course.

1. APS-C 16 MP: ok but not great. Covers 1/3rd of the useful area of film SLR lenses. The pixels are close enough to differentiate a bad lens from good ones, but not  a good one from an excellent one, especially at medium (f/4.0-f/8.0) aperture

2. APS-C 24 MP: probably the best one-camera test. As above, but the extra pixels allow to differentiate between good and excellent lenses

3. Full-Frame 24 MP: inadequate. Yes, it covers a 24x36 mm area. But it corresponds to 8 MP in the central 'APS-C' area, and in my experience, even 12 MP is not good enough to differentiate lenses

4. Full-Frame 36 MP: not good enough for testing the central area of the image, especially at optimal aperture, but useful to test the edges, and the only way to test the corners (but we must keep in mind that the angle of the ray path is a problem for many sensors far from the center)

5. MFT 16 or 20 MP: excellent to test 1/6th of the 24x36mm area. Corresponds to a 96 or 120 MP FF sensor! Surprisingly, allows to detect decentering of lenses.

In conclusion, for simplicity, I prefer to use one APS-C 24 MP camera, but the best is to use two cameras - a 36 MP FF and a MFT 16 or 20 MP.

 Belgarchi's gear list:Belgarchi's gear list
Olympus Stylus XZ-10 Panasonic LX100 Olympus Stylus 1s Panasonic Lumix DMC-FZ300 Panasonic Lumix DMC-GM5 +68 more
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