This flash unit is considerably powerful. It is made for use with Sigma cameras. The auto-zoom function will set the optimum illumination angle in conjunction with the focal length in use, from 24-105mm. This flash head can be tilted up and to the right by 90-degrees or to the left by 180-degrees for flexibility in using the bounce flash. It can also be moved down by 7-degrees for close-up photography. The Sigma EF-610 also offers a manual flash mode which can be set to full to 1/16 power. The auto power-off function will save your batteries and keep your flash working as good as new for the duration of its life.