What is the best looking 4K footage settings on the Sony A1?

The Sony A1 can shoot 4K footage in FF mode and APS-C mode, and at various frame rates. In addition 10 bit capture and 4:2:2 vs 4:2:0 capture is possible at various bitrates. What option gives the best looking footage in terms of detail, and how easy is it see differences?

I did some tests on a tripod shooting footage on my A1 in 4K FF and APS-C, and at various frame rates. I adjusted the position of the camera further from the target when shooting APS-C, so that I would get the same framing. I used a sharp lens and plenty of light to get the best IQ. In real low light the APS-C footage will have more easily visible noise and somewhat lower DR, but that was not an issue in my tests, as the ISO was low.

I viewed the resulting footage on a 4K 32" BenQ monitor sitting about 27" in front of my eyes. I also captured frame grabs of each of the video clips in camera, and viewed them.

My preliminary finding is that I will be happy to use any of the 4K frame rates in either APS-C or FF (so long as I have plenty of light), as it is difficult to see differences in overall IQ when viewed on a quality 4K monitor close in front of me, and the differences are minor in actual practice. Choose APS-C/Super35 crop either On if you need the additional equivalent focal length or Off if you don't without overly worrying about any affect to IQ.

Note that on the Canon R5, there are two FF 4K modes, 4K High Quality, and 4K standard, and it is really easy to see the difference between the two. See for example, https://www.dpreview.com/reviews/canon-eos-r5-review/7

and use the comparator to compare the various 4K FF options. This is not a knock on the Canon R5, as the 4K HQ FF mode is probably a little better than the best 4K FF mode on the Sony A1. However, the Canon quickly overheats in the 4K HQ FF mode, and takes a long time to cool down.

Of all the test footage I shot with the Sony A1, the 8K footage is clearly superior to the various 4K footage, even when viewed on the 4K monitor. I was using Quicktime to play back the 8K footage on my 16" M1 Max MBP, on the attached 4K BenQ monitor, and QT has the option of zooming in on the footage during playback, and the detail visible, compared to the 4K captures, is amazing.

I think if you want the best 4K footage from the A1, shoot 8K, then during the editing stage, use some combination of cropping and/or down-rezing to get the best 4K footage (of course you will be limited to 24p or30p, and you are capturing in 4:2:0). This of course adds extra work in the editing stage, and depending on the computer you are using, it may be impractical. Fortunately the recent M1 and M2 Macs can easily handle editing multiple streams of 8K video, often without the fans coming on.

At this point, I am not going to post my frame grabs, but will do so in the future. The reason being is that I made some minor mistakes when capturing the footage (I don't think they will affect the final conclusion), but I think it wise to re-capture the footage and make final conclusions from that.

One mistake I made was having Image Stabilization set to Active. This will slightly diminish the IQ of 4K FF video shot at 24p and 60p. It doesn't affect the IQ of 4K FF 120p or 8K 30p footage, since Active IS is not available in those modes, only Standard. Having Active IS on also slightly affects the framing, which messed my framing up slightly. The second mistake I made is that I was not always using the highest bitrate capture for each section of footage captured.

Therefore, I plan to re-shoot the footage, on a tripod, with IS off, and use the highest bitrate, and 4:2:2 capture (when possible), and more carefully position the tripod to get the FF and APS-C footage framed as identically as possible. Unfortunately I will be busy with other projects for more than a week, so it will take some time.

One other caveat to A1 shooters is that if you have APS-C/Super35 set to Auto, when you shoot 4K video at 24p or 60p, the camera will default to Super35 mode, even if you have a FF lens attached. This might be because Sony considers the Super35 capture to be better, but who knows? If you shoot 4K 120p or 8K 30p, the camera will stay in FF mode. You can force 4K 24p and 60p to shoot in FF mode by setting the APS-C/Super35 setting to Off.