M Sync refers to a flash synchronization connection found on some older cameras, designed specifically for use with flashbulbs rather than modern electronic flashes. The "M" stands for "medium" or "mechanical," indicating the timing required for the bulb to reach full brightness before the shutter fully opens.
Understanding M Sync is important for photographers working with vintage cameras or historical photographic equipment. Correct use ensures proper exposure when using flashbulbs and preserves the authenticity and functionality of classic photographic setups.