Canon 1D Mark III Flash
Canon EOS-1D Mark III Flash
The Canon 1D Mark III's X-Sync speed is 1/300 second, and a High Speed Sync option synchronizes the flash with all shutter speeds available on the Mark III, from 1/8,000 to 30 seconds. (Note though, that a full-power flash almost invariably lasts longer than 1/8,000 second, so you won't see the full flash power when working with a shutter speed that fast.) When using a wireless capable Canon EX flash unit, you can also sync up wireless slave units for greater coverage, with no connecting wires, special codes, or anything. Full TTL flash metering is available even with multi-flash wireless setups.
Other flash related options available on the Canon 1D Mark III include evaluative or average flash metering, first- or second-curtain synchronization, in-camera access to Custom Functions specific to the attached Speedlite model, and the ability to disable the external flash while still using its AF assist beam for low-light photography without flash.
Flash Test Results
The Canon EOS-1D Mark III does not feature an on-board flash, thus we did not perform any testing here. Performance will depend on the external flash in use.