Flash synchronization
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In photography, flash synchronization or flash sync is the synchronizing the firing of a photographic flash with the opening of the shutter admitting light to photographic film or electronic image sensor.
An example of improper synch. Either the flash is firing too late or the shutter speed is too fast (shutter moving vertically). Note the different exposure levels.
PC-socket
Hot shoe
Videos
A hot shoe is a mounting point on the top of a camera to attach a flash unit and other compatible accessories. It takes the form of an angled metal bracket surrounding a metal contact point which completes an electrical connection between camera and accessory for standard, brand-independent flash synchronization.
Canon EOS 350D Hot shoe
Proprietary hot shoe used by Minolta and older Sony cameras (Konica Minolta Maxxum 7D)
Minolta SRT101 accessory shoe without electrical function