Snapshots - 'snaps' has been around for a very long time and I suspect may have come from the snap the shutter release on a box brownie makes when you flick it over.
Also used to differentiate casual photos from the posed photos made by professional studio photographers who's expensive shutters did not snap. BTW nearly all pro wedding photos originally were posed studio shots. Guests might take some snaps of the wedding party squinting into the sun with their box brownies. Powell
