The pop-up flash on an SLR is convenient, but the light it creates is harsh and causes dark shadows. The Puffer transforms light from a pop-up flash, softening the quality so flesh tones look much more natural, and shadows are more detailed. It even helps fill in shadows on the bottom of pictures caused by a lens (or lens hood) blocking the light from the flash. The Puffer mounts to any camera's hot shoe (exc. Sony Alpha) and adjusts for proper fit regardless of the camera size. No change in camera exposure mode or other settings is needed, and the Puffer is compact for easy storage in your camera bag. Not compatible with Canon T4i