Shutter speed not stable?

[tpatana]

This happened me earlier time too, and today more often than earlier.

I have green H+ on the screen and set for 12fps shutter. Fast card which records 8k (if needed so it's not slowing it down either).

At semi random times, the camera noticeably slows down. The 12fps sounds the usual trtrtrtrtrtrtrtr. But at times it goes chonk-chonk-chonk-chonk, I'm guessing around 4-5 fps. Next shutter press might be back to fast, or could be slow. Happened with fairly full Canon OEM batteries (2x in grip) with native RF lens (28-70).

Today it was hotter than usual, but it should impact shutter speed that much? Especially as it seemed randomly go fast or slow. Also each shutter press it didn't change in-between, so either it was 12fps whole burst or the slow speed whole burst, it never changed during the burst.

 

[Rob2563]

Hope this helps.
HIGH SPEED CONTINUOUS + - This is the fastest option the camera has, that can work on the mechanical shutter or the electronic first curtain shutter option. This can shoot at 12 frames per second which will be maintained whilst the shutter button is depressed as long as the shutter speed is 1/1000 second or faster and there is at least 50% power in the camera’s LP-E6NH battery.
The symbol depicting the High speed continuous + on both the black Q screen and in the viewfinder when set, changes colour according to the speed that the camera is able to give. If it is displaying in green then you will get 12 frames per second. If it is displaying in white you will only get 9.2 frames per second and if it is flashing in white you will be down to 6.8 frames per second. To achieve the maximum speed of 12 frames per second the Wi-Fi needs to be not connected, the flicker reduction needs to be turned off and the camera needs to be using compatible lenses which is any RF lens or one of the compatible EF/EF-S lenses. The aperture also needs to be set to its maximum or widest aperture.

 

[tpatana]

Yes there was green H+ so in theory it should have been 12fps all the time, but some reason it was now only occasionally. Don't remember what the flicker setting was but it shouldn't alternate between fast and slow if it was enabled, and last time when this happened I remember disabling flicker detection and it still happened.

 

[tpatana]

Also I did shoot at 1/500, not 1/1000 or faster, but again if that made the difference, wouldn't it impact all the time and not just occasionally?

 

[PB Aus]

What are the conditions for shooting at the maximum burst during high-speed continuous shooting? (EOS R5)

When the Shutter Mode is Set to [ Mechanical ] or [ Elec. 1st-curtain] EF Lenses Supporting 12 Shots/Sec. Continuous Shooting When the Shutter Mode is set to ...

my.canon

This article from Canon Malaysia explains the conditions for 12fps (with R5) and some reasons why that may fluctuate as well......PB

 

[tpatana]

I wonder if the room temperature impacted the speed, but it'd be strange to drop to half while the green H+ was still showing.