This Polaroid macro LED ring flash attaches to canon brand hot shoes and macro-capable lenses with mounting ring diameters between 52mm-77mm- seven adapters are included with this package. The power pack attaches to the cameras hot shoe through which all synchronizing electrical signals travel. : : You can control the output level of the LEDs and select all or half of them to fire 32 LEDs for full lighting, 16 LEDs to create purposeful shadows on three dimensional subjects. You will also be able to change from flash firing mode to constant on. Constant on will let the camera decide which exposure is best and provide continuous light when using video cameras or the HD video mode in compatible digital cameras. : : A ring light is the best source for close up photography. And that makes the Polaroid macro LED ring flash the perfect choice for photographers who require shadow free illumination perfect for medical scientific and forensic photography.