One of the things many photojournalists find annoying about SLRs, both film and digital, is the noise they make. As camera technology advanced and motor drives got built into cameras they not only got bigger, they got significantly louder. The whisper quiet click made by Leica M series cameras is one of the reasons many photojournalists used Leicas for documentary work.
I think one of the most overlooked features on the Canon 5D Mark III is the Silent mode. Put the drive into the S mode and it dampens the sound so it’s barely audible. It slows the camera down a little, including slightly more shutter lag, but I think it’s worth the small trade off when you’re trying to be discrete. The 5D Mark III doesn’t sound like a cannon when it makes a picture, but it’s pretty loud. It’s much quieter in the Silent mode.
I use the silent mode a lot when I’m working in a temple, mosque or church – when I’m covering something spiritual and I don’t want the camera’s noise to disrupt what’s going on. There’s more on manipulating the 5D Mark III on Canon’s Quick Start Guide.
The silent mode isn’t something I thought about when I bought the 5D Mark III and I don’t think it’s a deal breaker, but now that I have a camera with a stealth mode, I find myself using it more often than I ever thought I would.