Canon R5 Issue: Same image, same settings but totally different exposures, taken one second.

[camera3]

Canon EOS R5 Issue: Same image, same settings but totally different exposures, taken one second apart. WHY is this happening?

I have TWO Canon EOS R5's and it seems to be happening on BOTH. I'm using a Canon 35mm 1.4 with adapter.

It also occasionally will show the incorrect exposure on the back screen despite exposure simulation being on. Not all the time, just occasionally?I've attached a photo. I've obviously blanked out the invite information for the couple's privacy.

What's going on?!

[rs-eos]

Wondering if the aperture blades are sticking in your lens? And not always able to close down?

Do you have other lenses you can try along with using f/14 or another stopped down value?

[camera3]

Thanks for the reply. You might be right with the lens. It's the only common element here.  I'll test with another lens. Frustratingly, it's not all the time, just occasionally. Maybe 3-5 times within a 10 hour shoot.  But I'll test that out. Thanks again!

[Stephen]

(Not a tech) Could it be the Auto White Balance? The first image is skewing gray, while the second is skewing white. There isn't a lot of contrast in the shot. 

Also - are you shooting under fluorescent or LED lights? Do you have Anti-Flicker enabled? It could be the lights cycling, and while we (humans) don't see it, the camera might. (I'm just guessing because I don't have enough info to go off of.)

[camera3]

No flicker enables and It's only natural light in this particular image. It happens often, so that photo is just one example sadly. Indoors, outdoors - and with auto white balance on or off. 😞

[jrhoffman75]

There was similar post a few weeks ago:

EF 35mm 1.4 Overexposing Images - Canon Community

Is your lens an adapted EF lens? Maybe a generic problem with that lens?

[camera3]

Thank you!! That seems to make more sense given the testing on two different R5's. It must be an issue with the lens. Yes, it's the canon 35mm 1.4 (not an RF lens).

[ICEngineer]

I don't know if this is the same problem: I see the opposite effect with my R6, usually when the camera is waking up after going to sleep. The image is greatly overexposed, and the exposure doesn't correct within a few seconds. I usually cycle the power, and after power-up the exposure returns to normal. In my case it's the 24-105 f/4 kit lens.