I don't have a 7D anymore but the manual says it's only available in Live View mode which means that the mirror will already be in the up position so it should be quieter. I accidently set my 1D mark 4 in silent mode at an air show & it really confused me for a few minutes. It works in the normal shooting mode on that body.
"A skill is developed through constant practice with a passion to improve, not bought."
