114Using Non-Canon Flash UnitsSync SpeedThe EOS-1Ds can synchronize with compact, non-Canon flash units at 1/250 sec. or slowershutter speeds. With large studio flash, the sync speed is 1/125 sec. or slower. Be sure to testthe flash to see if 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 isthreaded to prevent inadvertent disconnection.• There are studio flash units whose sync cord polarity is oppositefrom the camera’s PC terminal. Such flash units do not work withthe EOS-1Ds camera unless the polarity of the sync cable ischanged. Consult the manufacturer of the flash unit or purchase acommercially-available polarity conversion cord. The camera’s PCterminal polarity is shown in the figure on the right.A flash unit attached to the camera’s hot shoe and a flash unit connected to the PCterminal can be used at the same time.• If the camera is used with a flash unit or flash accessory dedicated to a anothercamera brand, the camera may not operate properly and camera malfunctionmay result.Also, do not connect to the camera’s PC terminal any flash unit requiring 250 V ormore.• Do not use a high voltage flash on the hot shoe. It might not fire.+ (plus)– (minus)
