mirror & Q-tips need help

On a quick test with my 5D, I got the same readings on my wall (1/60 @f2.8 ISO3200) regardless of what metering mode I was in.

gjl711 wrote in post #2276391
A front surface mirror is very fragile, but touching it very lightly with a q-tip is not going to wreck the mirror. The mirror itself is actually a bit more durable than many are making out as anyone who has owned a reflective telescope for any length of time can tell you. The damage is more likely to occur in that any pressure applied against the mirror will knock it out of alignment before it will remove the coating. If the dust is annoying, use the rocket blower so something similar, not canned gas. That usually knocks it off. If it’s still there, then try to live with it. It won affect you image quality. If it bugs you so much that you just have to get rid of it, don’t use a dry q-tip, use a micro-fiber cloth and use the lightest of touches you possible can just on the speck itself. Or, take it to a camera shop and let the gorilla behind the counter do it for you.

Jon wrote in post #2277218
Do all 3 settings give you comparable exposure? That's why a uniform surface - to rule out differences in the different metering areas.

Eagle wrote in post #2280656
Agree. Don't worry you didn't damage anything. The worst you would have done with your methodwas to leave cotton fibers on the mirror. Just don't do it again. Got scared and learned a lesson.