Electronic Flash EF-500 DG ST can be used with Sigma's and other manufacturers' AF 35mm SLR cameras and Digital SLR cameras. It has a maximum guide number of 165 in feet or 50 in meter at 105mm focal length (ISO 100). Projection angle of the flashlight is set automatically to match the lens' focal length ranging from 28mm wide-angle to 105mm medium-telephoto. It incorporates a wide panel that expands the angle of illumination that of a 17mm focal length lens.
It enables full automatic flash photography by TTL automatic flash exposure control. It includes S-TTL flash photography for Sigma, 3-D multi-sensor balanced fill flash function and D-TTL flash photography for Nikon, E-TTL flash photography for Canon, ADI flash photography and P-TTL flash photography for Minolta.
For bounce flash it can be tilted 90° upwards and 7° downward for close-ups. Also, it can be swiveled 180° to the left and 90° to the right. In addition manual flash can be set to full and 1/16 output levels in 2 steps. Covering focal length of the flashlight can be seen on the LED panel and the flash ready signal can be seen in the viewfinder. EF-500 DG ST incorporates auto power off system.