The STF-8 Twin Flash from Olympus offers shooters a completely weatherproof macro flash option. It features adjustable ratios to help control the contrast of the scene and how much light is coming from each side. As an advanced flash unit, the STF-8 is equipped with numerous features and settings that will help photographers. Shooters can use the STF-8 as a wireless master TTL flash to control up to 4 groups of flashes set up off camera. Also, the unit supports focus stacking and bracketing functions of select OM-D cameras. It runs on 4 AA batteries and the two included ring adapters allow it to be attached to select Olympus lenses. It is splash, dust, and freezeproof to 14°F for completely weatherproof design. The flash heads are designed to provide plenty of light, with a twin flash featuring a guide number of 27.9' at ISO 100 while a single head features a guide number of 19.7' at ISO 100. Additionally, it will cover a 12mm lens on Micro Four Thirds format camera and each flash head can be tilted from -40 to 60° i.e Flash heads can be tilted upward from 0 to 60° and downward from 0 to 40°. It has manual flash power settings of 1/1 to 1/128.