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Higher megapixel sensor -> less resolution

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buellom Contributing Member • Posts: 800
Higher megapixel sensor -> less resolution
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Hi all,

I'm wondering why this issue wasn't discussed yet more broadly. The German website digitalkamera.de reviewed the new Sony 4/20-70G lens. A lens I really would like to see for RF. (There were patents from Canon for a 17-70 full frame lens.)

They tested the lens on the Sony 7III (24 MP), 7RIII (42 MP) and the 7RV (60 MP).

It's certainly not a big surprise that the resolution drop at the borders is higher in % on the A7RV than on the other cameras. The lens is not that good at the borders, so the lens limits the resolution of the the sensor-lens combo.

My assumption always was you can't lose with higher resolution (all else equal). A bad lens won't let you use the whole potential of the high resolution sensor but you won't lose resolution compared to a sensor with less resolution.

It seems I was wrong: The resolution in absolute terms at the borders was less on the A7RV compared to the A7RIII. It means that the higher resolution camera captures less detail than the lower resolution camera (at least at the borders). A higher resolution camera here has a clear disadvantage. And the difference of the border performance is not small: e.g. @38mm and f4: 44.9 Lp/mm (line pairs per millimeter) on the A7RIII compared to 29.6 Lp/mm on the A7RV.

The numbers are here (at the end of the page):

Sony FE 20-70 mm F4 G im Test - digitalkamera.de - Zubehör-Tests

The explanation in the review is that smaller pixels have more issues with aslant light rays compared with bigger pixels. This would mean that this issue is more likely to happen with wide angle lenses and wide angle zooms than with tele lenses.

Of course it does not mean that it will be the same with Canon cameras. Canon might have a different micro lens layer on the sensor. But, at least for me, it's something to look for before investing in a high MP camera.

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