On most devices pressing the volume key brings up a slider with a little gear icon. Touch that and it expands to separate sliders for notification, system and media volumes.
However it may not be that easy. I just tried on my tablet and had to completely mute the device to silence the shutter noise. So have a go, but no promises.
On my phone I can just turn the sound off in the camera app - HTC are more sensible that Samsung
