I am on a photo trip to Southern Utah and notice that all the photos taken by my fairly new (around 2,000 clicks) Canon R5 have the same artifact seen in the upper left. Occurs on photos taken with four different EF or R lenses. My only thought is a grease splatter on to the sensor, but I thought this doesn’t happen with mirrorless cameras. Any thoughts or advice for now? When I get back home I will take a look at the sensor…I have the proper magnifying glass an a sensor cleaning kit.
Grease spatter DOES happen on mirrorless cameras, especially if you don’t turn them off when you change lenses and you’ve got it in electronic shutter mode when the sensor is no longer covered by the mechanical shutter. I’ve seen this with my R5. A sensor cleaning worked. Mine looked like I sneezed into the camera. 
1 Like
Thanks for the info Mark. That’s reassuring. I had hoped it was a simple problem with an easy fix.