I just did an experiment. The scene was composed of side trees with dense green leaves, an apartment gate, a parking lot with cars. The evening sun lightened some part of the scene. There was strong wind. I used one lens on 5D3 and 650D. The cameras were set up on a tripod. The whole experiment was done within 30 minutes. The focus length of the lens was about 28mm. All of the parameters in MLV App were default (except one footage I will mention it later). I used MLV App to process the raw into prores 4444. The footage was viewed in Potplayer on my 27 inch computer monitor of 1920x1080 in full screen mode.
The following modes were tested:
5D3 1x1 UHD
5D3 1x3 anamorphic UHD 10 bit color depth
5D3 1x3 anamorphic UHD 14 bit color depth
5D3 1x3 5.7k anamorphic 10 bit color depth
5D3 1x3 5.7k anamorphic 14 bit color depth
650D 1x1 3K
650D 1x3 anamorphic UHD 10 bit color depth
650D 1x3 anamorphic UHD 14 bit color depth
The common acquisition parameters were 14-bit lossless compression. Aspect ratio was set to 3 to make all modes continuous. The acquisition period was 1 minutes for each take.
Here are my observations:
First, 10 bit color depth modes and 14 bit color depth modes were not different in terms of IQ, because the MLV App parameters were default.
Second, confirming my previous experiment, I can see that the details of leaves were noticeably better in 5D3 1x1 UHD mode than in 5D3 1x3 anamorphic UHD mode. For the apartment gate and the park lot and the cars, the difference was not noticeable. Some of the trees had wind shake, so the difference was not noticeable. Thus, motion blus will mask the difference.
However, the difference of 5D3 1x1 UHD mode and 5D3 1x3 anamorphic UHD mode was much greater than the difference of 650D 1x1 3K and 650D 1x3 anamorphic UHD. In addition, 5D3 1x3 anamorphic UHD 14 bit color depth footage meta data were not recognized in MLV App, so I had to manually change the stretching ratio to 0.33. I suppose that the 5D3 1x3 anamorphic UHD submode is not optimized. I recommend not using this mode, even for testing. It will be great to have a separate preset of 1x3 UHD 60 fps on 5D3.
Third, 5D3 1x3 5.7k anamorphic was as detailed as the 5D3 1x1 UHD, if not more. Actually watching these footages again, I think that 5D3 1x3 5.7k anamorphic was noticeably a little bit sharper than 5D3 1x1 UHD, not much though. Therefore, there is no advantage to use 5D3 1x1 UHD, considering that 5D3 1x3 5.7k anamorphic 14-bit color depth is continuous, except that 5D3 1x1 UHD has much shorter processing time in MLV App. In the future, a test on the details of 5D3 1x3 5.7k anamorphic vs 5D3 1x1 5.7k will be more proper. If the difference in IQ is not significant, as demonstrated on 650D, I would rate 5D3 as a 6K Raw camera. Red Komodo users, BMPCC 6K Pro users, Canon C500 MKII users are welcome to challenge this claim.
Forth, 650D 1x1 3K was the sharpest of all the modes tested, 650D 1x3 anamorphic UHD was very close to 650D 1x1 3K in terms of IQ details. The sharpness of these modes is consistent with my previous experiments on 650D, so I consider that it is true. I am confident that the general audience will not see the difference between the 650D 1x3 anamorphic UHD and the 650D 1x1 3K in many commercial theatres with 2K projectors, neither by watching cable TV, nor by watching internet streamed videos. Therefore, for myself, I will use 1x3 anamorphic UHD 14-bit color depth on 650D as the main mode. It has a data flow of 55 MB/s thus continuous on 650D. I would rate 650D as a 4K Raw camera. BMPCC 4K users, Canon C70 and/or C200 users are welcome to challenge this claim.
Fifth, I am surprised to see that 650D modes were noticeably sharper than 5D3's. More experiments are needed to verify if this is true.
Future directions:
All of the above observations are based on "unprocessed" neat footage. I will do PP for each footage to improve the IQ. I think that PP will mask or at least mitigate the difference observed.
More studies with different approaches to test 1x1 vs 1x3 modes by community members are helpful. I am curious to see if results from similar experiments viewing on a 5k monitor will be the same.