The Electronic Sigma EM-140 DG Ring Macro Flash is designed to work with both AF 35mm film and digital SLR cameras of all popular manufactures. It is ideal for photographing subjects in fine detail when the shadowless mode is used and is extremely effective for scientific and medical applications. Dual flash tubes can fire simultaneously or separately. Using only one flashtube creates shadow, which can give a three-dimensional feeling to the subject. The flash features a guide number of 14 with ISO 100. The Modeling Flash function makes it possible to check for reflections and shadows before actually taking the flash picture. A wireless flash function is also available when the EM-140 DG is used as master and the EF-500 DG Super as a slave unit for creating fine shadow details. High-speed synchro and exposure compensation functions are also available for advanced flash photography.