EOS R6 Mark II - constantly changes ISO randomly & white balance periodically

[fstopPhoto]

I started using this camera last September (2024) and every single time I use it the ISO randomly changes on its own.  I typically shoot all indoor, low light situations with ISO 3200 - 4000.  Exposures will be fine the suddenly either dark or overexposed.  The ISO might go down to 400 or 640 or up to 12,500 for no reason whatsoever.  This happens multiple times a day, every single day I use it.  I'm ready to throw it out. 

I have turned the return to auto ISO off and this does absolutely nothing.  It's driving me crazy!  Nothing works to change this.  I have set the ISO range to a low of 3200 and a high of 6400, which I don't want it to be that high but that's the only option, set the ISO to 3200 and it will still change ISO to AUTO or to any ISO between 3200 and 6400 for no reason.  

I thought maybe my forearm is touching the screen and somehow changing the ISO, which is hard to believe, so I turn the camera off when walking.  I can turn it back on and the ISO has changed from my original settings.  I can shoot a series of photos and it changes ISO on the next photo.  

I have reset the camera to factory settings.  The firmware is up to date but I downloaded it again and reinstalled the most current firmware and it still does it.

This is absolutely insane and I can't figure out why it's happening or how to get it to stop. 

Every once in a while the white balance will also change randomly but that has only happened a few times in the last 7 months of use, whereas the ISO changes every single day, multiple times a day.  

Any suggestions or Canon employees who can help with this?

Thanks,

Dave  

[Waddizzle]

Pay attention to how you hold the camera between shots.

I used to have similar issues.  I would seem to get random under/over exposures for no apparent reason.  Like you, I had just bought a new camera. At some point it I noticed that it was not happening, anymore.  

I never did figure out why it stopped with any certainty.  All I know for sure is that I had begun using Back Button Focus. It gave my thumb something to do besides linger and wander around the back panel. I guess I was tapping [AE Lock] or something.  I don’t know.

[LeeP]

Although this is not directly related to the question above, the detents for the mode dial on my R100 are so soft that I can inadvertently change modes holding/picking up the camera. Sometimes the most simple explanation is something we overlook because we tell ourselves it can't be that simple. Given the buttons on the backside of Canon cameras, the notion of touching something is plausible. I too would feel a sense of rage at having a nice camera like an R6 and find it "possessed".

[LeeP]

Waddizzle's explanation is plausible and the likely source of the issue, but you can always send it in for a once over if your frustration is getting to the fist through drywall level. Doing so would either tell you that something is wrong--and potentially fixable--or that nothing is wrong and Waddizzle's explanation of inadvertently touching/bumping something is possible. 

Although I have not seen it with my Canons, I have had other cameras that were sensitive to battery strength and in one case replacing the battery was the savior. I am NOT suggesting that you buy another battery to test out this theory, but if you have a back-up battery that you never use, charge it up and see what happens. This suggestion is pure spitballing rather than any empirical knowledge of the issue. Though I feel empathy for your predicament, I realize that does little to solve the issue.

If a solution doesn't come from this discussion, have it looked at. Good luck in your endeavor to solve this issue and keep us posted if you figure it out because it helps to know that too.

[p4pictures]

Which shooting mode are you using, is it one of the custom modes C1/C2/C3?

With custom modes the setting for auto update stored settings is important. If set to disabled, then any changes made to the camera - ISO, custom functions, auto ISO range etc, are not saved. So when the camera switches off, or is switched off or the mode changed then the changes are lost. 

[fstopPhoto]

I shoot in manual mode 99% of the time.  Last week I got so fed up with it that I set a custom mode and set a low ISO of 3200 and a high of 6400 and it still changed randomly.  

[p4pictures]

When you set the ISO range, did you do both the auto range and the manual chosen range?

From the EOS R6 Mark II ISO Speed setting menus, I see this on my camera when I set the ISO speed range to be from 3200-6400 as you described. This range setting only applies to ISO values chosen by the photographer. Since even with this range limitation the photographer can also choose AUTO ISO. In my second screen capture you can see exactly that.

However the range for AUTO ISO is determined by the AUTO range setting, and in my camera that is set for 100-25600. This means that if I choose auto ISO then the camera can work with any ISO between 100 and 25,600. IF you want to restrict AUTO ISO then you need to do the same 3200-6400 limitations as you do for the manually chosen ISO in the second line. The two are independent. 

Additionally check what you have set in the camera custom functions for Speed from metering/ISO auto. When this is set to the default setting - Restore Auto after metering - then if the camera is set to AUTO ISO, you can turn the ISO dial and change ISO to a value in the 3200 - 6400 range.

However as shown below, there is a grey AUTO icon next to the ISO value, and this is to indicate that once the metering timer expires the camera will return from the current value to auto, which is what has happened in the last screen.

[fstopPhoto]

I set all ISO ranges to the same thing.  There is no option to not include Auto when setting speeds.  Speed from metering is turned off.  

[p4pictures]

At this point I am somewhat at a loss as to how the camera is changing ISO beyond the ranges you specified. I have tried this with my own EOS R6 Mark II camera in both M, and a custom shooting mode configured with the same M mode and ISO settings, and there is no way for me to replicate your problem.