I received my Canon 5D Mark III's last Monday and have been shooting pretty much every day with them ever since (short review: AF finally works, thank goodness, and the hand grip is deeper, which is nice). In perusing the online reviews, I saw a mention of the Silent Shooting Mode. Having used this on the 5D Mark II, my impressions were that it was a pretty interesting idea, but badly implemented. Basically, on the Mark 2 the mirror would stay up as long as the shutter button was held down, making for an exceptionally long blackout time and having to consciously think about releasing the button every time you took a picture.
With the 5D Mark III, the feature has been improved immensely and essentially just slows down the mirror a bit to decrease the sound of it hitting. You get a slightly longer mirror blackout, but otherwise there's no difference except for the sound, which is ridiculously quiet. Like, quiet enough to proclaim on Twitter that it seemed even quieter than my trusty (read: unused) Leica M6.
So, is it?
In search of some answers (and waiting for some RAW images to be outputted), I set up a little test, placing both cameras on a couch and measuring the sound of their shutters using dB Meter Pro on my iPhone. I initially was going to put a lens on each one, but sadly, I sold my last Leica lens a few years ago, and have for some reason held onto the M6 body thinking that one day I might pull it out again and run few rolls of Tri-X through it. So, I decided to do the test with the shutter caps off (hello sensor dust), and the iPhone positioned about two inches away from each (yes, I measured).
Anyway, on to the test. I did five actuations for each (both at 1/500), making sure the phone's microphone was positioned the same distance away.
Here are the numbers (measured in dB):
Leica M6 : 100, 101, 103, 102, 102.
Average: 101.6 dB
Canon 5D Mark III (in Silent Mode) : 98, 99, 99, 98, 100.
Average: 98.8 dB
Here's an audio file, with five actuations of the Canon, then Leica. As you can hear, the Leica's shutter sound is shorter and a bit sharper, while the Canon is stretched out a bit, but sounds more dampened.
So, what does this all mean? Comparing a film camera that ended production in 1998 with the latest/greatest from Canon doesn't really count for much of anything, except that the Leica has always been held up as the paradigm of quiet-- the camera by which all others are measured. More importantly, this is a killer feature for a camera that seems to have fixed the majority of the issues its predecessor had, and then furthers its appeal by improving a feature that most photographers didn't even know existed.