Not sure if you remember, but my friend, a proud owner of 50D did some "spring cleaning" of her mirror and focusing screen. In the process she ended up actually scratching the focusing screen (I think). I went with your advice, used the rocket blower and removed most of her lovely black cashmere sweater residue and some weird dust, but the scratch and some funky threads were there, very light, but they were there. Now, i recently became an owner of 10-22mm and decided to change my focusing screen to EF-D to get some help with leveling while shooting architecture... of course she wanted such grid as well. I figured this may help with the scratches, so we changed her focusing screen as well (in MY house, I did it, sterile conditions, no little ones present [Y]) Now she has beautifully clean viewfinder. Yay!


Ed, thanks for all your advice. It is also a lesson for me NOT to ever lend her my equipment or lenses[:P]


No matter how she begs.