sony crops sensor resolving power? DXO question.

Started Sep 18, 2016 | Discussions thread
Pixel Pooper Senior Member • Posts: 2,510
Re: sony crops sensor resolving power? DXO question.
1

The problem with perceptual megapixels is that no one outside of DXO knows how they come up with the numbers, but that doesn’t stop people from confusing them with actual MP and quoting them as gospel. If you read DXO’s rather vague explanation they call perceptual megapixles “A great metric backed up by science and the industry” but they don’t share any of the “science” behind it, and I have not seen any examples of it being “backed up” by the industry.

What they do say is: The number of P-Mpix of a camera/lens combination is equal to the pixel count of a sensor that would give the same sharpness if tested with a perfect theoretical optics, as the camera/lens combination under test.

One example of P-Mpix not matching reality is the FE 90mm macro which scores 42P-Mpix on the A7RII, so it is equal to “perfect theoretical optics” which shouldn’t be possible, and if P-Mpix is averaged across the whole frame then in the centre the FE 90mm must be even better than perfect theoretical optics.

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