The Sigma EM-140 DG Ring Flash is ideal for photographing subjects in fine detail - close-up photography - and is extremely effective for scientific and medical applications.,,,Dual flash tubes can fire simultaneously or separately. Using only one flashtube creates modeling, which can give a three-dimensional feeling to the subject. 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, where 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 functions are also available for advanced flash photography.,,Fully dedicated with S-TTL with Sigma SA photo or Digital cameras,Wireless TTL flash control (4 channels),High Speed Synchro flash,Stroboscopic effect (power level and frequency customizable),Modeling light, also provides AF assist,Backlight illuminated LCD panel