Detailed item info Description Ideal for macro photography, the Sigma EM-140 DG is a multifunctional macro flash designed for use on all modern digital SLR cameras and AF 35 mm film cameras. This macro ring flash is compatible with most Canon, Nikon, and Pentax cameras. Boasting an impressive lighting performance, the Sigma camera flash is designed to take super-detailed photographs, such as those needed by scientists for capturing minute details of research or by medical professionals who document detailed images for scientific purposes. The Sigma EM-140 DG easily configures to fire either one or both flash rings. Firing both eliminates shadows to show ultra-fine details. On the other hand, firing a single ring shadows the subject enough for a three-dimensional effect in the finished shot. In addition, the wireless flash control and high-speed synchronized flash are two key features of this Sigma camera flash. These features help the photographer to take advantage of advance flash photography techniques. Furthermore, the modeling flash function on Sigma EM-140 DG allows the photographer to check reflection and shadow effects to make adjustments before taking the shot. This macro ring flash has a guide number of 14 W/ISO 100.