Luminous Landscape Forum
Equipment & Techniques => Mirrorless Cameras => Topic started by: sbay on May 21, 2017, 04:00:48 pm
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I noticed a pretty big discrepancy in sharpness for DxO ratings on the 28mm f/2 lens depending on whether it was mounted on the A7R (36MP) or A7RII (42MP). It jumps from 24 to 35 P-MPix.
https://www.dxomark.com/Lenses/Compare/Side-by-side/Sony-FE-28mm-F2-on-Sony-A7R-versus-Sony-FE-28mm-F2-on-Sony-A7R-II__1516_917_1516_1035
Should I chalk this up to sample variation, measurement error, and/or recording error? Is this due to some weird scaling/normalization of their scores? The difference seems bigger than can be explained by the slightly higher res sensor in the a7RII.
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My guess would be that at least a big part of it is due to the fact that the a7R had a significant shutter shock issue with no electronic first curtain where the a7R2 largely got rid of that with both an EFC and a redesigned shutter to reduce shock.
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That makes sense. I had forgotten that the a7r did not have EFCS.
I went and looked at a bunch of other lenses on the a7r and a7r II. There was a consistent ~10 P-MPix difference in sharpness rating which would make sense if the EFCS is the issue.
sony 50 f/1.8 16 -> 26
sony 35 f/2.8 22 -> 32
sony 90 f/2.8 32 -> 42
sony 55 f/1.8 29 -> 40
sony 16-35 f/4 16 -> 26
sony 70-200 23 -> 35
sony 70-300 15 -> 24
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As far as I remember there is no normalization in DxO, the results are resolution dependent of the camera they are using... They explain that a bit here https://www.dxomark.com/Reviews/Looking-for-new-photo-gear-DxOMark-s-Perceptual-Megapixel-can-help-you where they introduce their perceptual megapixel sharpness measurement for lens.
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