Measuring rolling shutter: put a number on this issue!

[Samuel H]

I'm not really interested in the 4k 30fps mode, but I'd also like to see some 1080p tests, because softness there is what kept me away from the a6500: I do shoot slow motion often, and I don't mind cutting some 1080p shots with 4k footage but they have to be sharp 1080p shots.

[Dr_Jon]

BTW note here:
https://www.dpreview.com/reviews/son...ent=7117048566
Rishi suggests the A7III has a lot less rolling shutter in 4k/30p

[NorBro]

With most cameras, it always gets better with more frames per second or knocking down your system to a lower resolution.

So 4K/30p should be better than 4K/24p, but may not be better than 1080/24p. Some cameras may be pretty even all across the board.

[Samuel H]

When that happens, it's because you're using less information in order to create the final image. It's either cropping, skipping lines, or switching to a lower-bit-depth ADC path. But depending on the shot it may be worth it.

[Samuel H]

Just added the Pentax K-1 to the list. It's not a camera I would consider, but somebody was interested enough to shot the test clip and send it to me, so, here you go:

Pentax k1 1080p24 - 15.2 ms (15.9-15.7-13.9)

[Rdouthit]

Might want to add to the chart the result that DPReview saw when they tested rolling shutter on the A7III at 4k/30p: 16.7ms (!) with 1.2x crop. (Standard crop at that resolution.)

[Samuel H]

That's a lot faster than what I got at 25 fps. Did they test any other frame rates or resolutions?

[Rdouthit]

Yes, they also tested 4k/24p, where it matched your score of 25ms. Seems the slight crop pays big dividends in RS reduction.

[Samuel H]

Perfect. Added to the table. Thanks!

[Samuel H]

I get lots of questions about this (well, not so many, but over the years they pile up) so I updated the opening post with a detailed description of how I calculate these numbers