M-synch

M-synch is a flash setting or socket which synchronizes the firing of the shutter with the peak light output of a flash bulb.

Roughly speaking, FP or M-synchronisation is constructed to fire flashbulbs just before the shutter is fully open, allowing a build-up time, and X-synchronisation fires electronic flash exactly at the moment the shutter is fully open.

See also: Shadows, Mount, Balance, Value, Type