Canon EOS 20D EOS 20D Instruction Manual - Page 98

Using EOS-Dedicated, External Speedlites ¡ When using an external Speedlite, retract the built-in flash before mounting the external Speedlite. ¡ If the EX-series Speedlite's firing mode is set to TTL autoflash with the Custom Function, the Speedlite will not fire. ¡ If autofocus cannot be achieved, the external, EOS-dedicated Speedlite's AF-assist beam (if the Speedlite has an AF-assist beam) will be emitted automatically (except in modes). ¡ The EOS 20D is a Type-A camera that can use all the features of EXseries Speedlites. Using Non-Canon Flash Units Sync Speed The EOS 20D can synchronize with compact, non-Canon flash units at 1/250 sec. or slower shutter speeds. With large studio flash, the sync speed is 1/125 sec. or slower. Be sure to test the flash unit beforehand to make sure it synchronizes properly with the camera. PC Terminal ¡ The camera's PC terminal is provided for flash units having a sync cord. The PC terminal is threaded to prevent inadvertent disconnection. ¡ The camera's PC terminal has no polarity so you can connect any sync cord regardless of its polarity. ¡ If the camera is used with a flash unit or flash accessory dedicated to another camera brand, the camera may not operate properly and malfunction may result. ¡ Also, do not connect to the camera's PC terminal any flash unit requiring 250 V or more. ¡ Do not attach a high-voltage flash unit on the camera's hot shoe. It might not work. A Speedlite attached to the camera's hot shoe and a flash unit connected to the PC terminal can be used at the same time. 98