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Sony introduces the a7R IV with 61 Megapixel full-frame sensor - The Business !!!! (1 Viewer)


Well-known member
I think an important thing to keep in mind is that as the pixel pitch gets smaller, the maximum allowable airy disc (circle of confusion) also gets smaller. The numbers below are from some back-of-the-envelope estimates of sensor resolving power, so they might be off by a small amount.

On the d850, the pixel pitch is about 4.3um so the largest CoC you want is about 10.7um (about 2.5x the pixel pitch, due to bayer interpolation), so diffraction limiting begins around f/8 and will get bad by f/16-f/22.

On the a7r4, the pixel pitch is about 3.7um, so the largest CoC you want is about 9.3um. Diffraction limiting will begin around f/5.6-6.3 and will get bad by f/12-16.

This also means that smaller and smaller amounts of shake will cause the airy disc to wobble over other sensor sites. This will cause a loss of micro-contrast and blur.

The Fuji GFX 50 has a 51.4 MP sensor with about a 5.3u pitch. It will start getting diffraction limited around f/16 and get bad maybe around f/22-30.

If you do not pixel peep, you will not notice it unless you made a very very large print or crop a lot. Smaller pixels will show fewer artifacts from crossing the diffraction boundary. Also, the 61MP sensor, even if slightly blurred from diffraction, will still behave like a 30 - 40 MP sensor if you are not pixel peeping. Higher MP sensors will always show more detail (same size sensors) and software sharpening can help a lot, but you will lose the finest sharpness at lower f-stops.

Steve Perry has a nice video on this: https://youtu.be/N0FXoWdHXTk

Chosun Juan

Given to Fly
Australia - Aboriginal
.... Interesting to see you say that this camera finally outdoes the Nikon D7200, do you not rate the D500? .....
Of course I rate the D500 very highly. Rightly so. I just meant that from ISO 100-400 the D7200 sensor reigns supreme ..... still.

Chosun :gh:

Chosun Juan

Given to Fly
Australia - Aboriginal
I call BS on some of that. Why is he shooting at ISO 5000? Those shots are not sharp or clean when viewed at 100%. Those shots of the perching bird with the 200-600 are not that great.

I've started a new thread with some of my experiences with the camera.

I can only think that such a high ISO was a deliberate attempt to put the camera's IQ through it's paces, or eliminate any variables from the lens? I will have to go back and read it in detail later.

Chosun :gh:

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