Noticed a weird mirror/shutter issue with 5D Classic today.

I was shooting portraits for family, group shot of kids/toddlers so I was clicking away in hopes to get some with all of them looking and smiling. I was in manual mode and the shutter speed would have been anywhere between 1/400 and 1/800 depending on what aperture and ISO value I was on, and randomly it sounded and looked through the viewfinder like the mirror was staying up much longer than that, I would have guessed around 1/30 or even slower. But when I checked the photo and histogram after everything looked fine, none of the photos were overexposed. I didn't pay much attention to it at the time since I was busy. It didn't occur to me until later that I was probably hitting the limit on the buffer (I believe on the 5D it is 9 RAWs, and it writes pretty slow to the CF card). I suspect that at the buffer limit the mirror was still going up when I clicked the shutter but waiting for space to free up on the buffer to activate the shutter mechanism, and the shutter curtains were moving across as usual at the fast speed I set. I don't usually take so many photos in a short period of time so I rarely hit the buffer limit on this camera. Is this normal behavior, or a sign of something failing? For what it's worth I know for a fact that the shutter count is currently at about 58,000.

Heya,

I have a couple of 5Dc's. If you were shooting manual and you felt like it slowed down, it was likely buffer. If you were shooting AV, or any other semi-auto mode, maybe you did get something with a slower shutter.

I wouldn't worry about it.

If something was failing you would have noticed an issue with the images, such as a shutter issue or corrupt files or buttons not responding, etc.

As you pointed out, you likely simply met the buffer clicking away too fast. And it wasn't that the shutter slowed down, it was just that it didn't respond when you clicked because it couldn't take another image until the buffer cleared, so it felt "lagged."

Very best,

Thanks, yeah I usually shoot in aperture priority, but due to some harsh backlighting I didn't trust the metering to stay consistent for each shot, so I switched over to manual took a few test shots checking the histogram and then fiddled with it a bit when needed. I checked the photos again today, and the EXIF shows I was actually at 1/250 during these (which is correct) when I noticed this weird lag. Nothing out of the ordinary in any of the resulting photos, shutter speed, aperture, and ISO were all exactly as I had set, just that there was a very noticeable delay between the mirror going up and coming back down randomly when taking some of the photos which sounded like something between 1/4 and 1/30 shutter speed.