Canon just released firmware version 1.6 for the EOS R5; the big add in 1.6 is the new "Auto power off temp" option, with settings "Standard" and "High". Since the release, I've been testing how the new option affects overheating. It seems to be a big improvement. So I thought I'd share my results.
All tests were shooting the TV, so the camera had some motion to process. The room was about 19-20 °C (66-68 °F). Obviously the 30 minute record time limit (7.5 minutes in 120 FPS) kicked in, so I just pressed record again each time the camera stopped, until it actually overheated and shut down -- or I got fed up and went to bed.
In all cases, once the camera shut down, I stopped the test. Of course you can let it rest a bit and get more time out of it, but how much time depends on how long you let it cool. With infinitely many options, I couldn't be bothered testing this. The camera was allowed to get stone cold between these tests.
Auto power off temp = Standard
4k HQ 23.98 warning @ 31m 02s, shutdown @ 40m 18s
8k IPB 23.98 warning @ 25m 50s, shutdown @ 33m 57s
4k LQ 59.94 warning @ 1h 11m, shutdown @ 1h 41m
4k LQ 120 warning @ 14m 45s, shutdown @ 19m 53s
Auto power off temp = High
4k HQ 23.98 ran for 3 hours, no warning or shutdown, gave up
8k IPB 23.98 ran for 4 hours plus, white warning after an hour or so, red warning intermittent, no shutdown
4k LQ 59.94 ran for 3 hours, no warning or shutdown, gave up
4k LQ 120 white warning @ 22m 50s, red warning @ 29m 45s, shutdown @ 35m 54s
In the cases where the camera ran for 3 hours or more, it just didn't seem to be getting hotter, so I couldn't see much point in continuing. The camera was pretty warm after these tests, but not crazy; though the memory card was too hot to hold. It cooled down pretty fast, though.
For a mirrorless camera without active cooling, this looks about as good I would expect.
Obviously I can't guarantee that you'll get these run times. Individual variations between cameras, different environments etc., will all have an effect. In particular in the 8k test, the warnings were showing intermittently after the first hour or so, so the camera was clearly close to the edge.
Please bear in mind that in "High", the camera can get hot, so watch out for low-temperature burns if you're holding the camera for a while.
I've uploaded a more extensive write-up to my web site: https://moonblink.info/MudLake/gear/r516
