Compact in design and lightweight at only 116 oz the sigma ef 610 dg st gives photographers more flexibility and versatility this shoe mount flash features a guide number of 200 ft and an iso 100 with a lens coverage of 24 105 mm the sigma flash is designed with ttl automatic flash control for ease of use the sigma flash has a straightforward hot shoe mount for easy installation on the camera with a built in wide panel the shoe mount flash is able to cover the angle of 17 mm if the ph