Flashes allow the photographer to create light when a picture might not otherwise be attainable.  The decision to use flash may be out of necessity from insufficient available light, or to light subjects creatively in ways natural light cannot.  Common uses of flash include subtle filling in of shadows on a person’s face, stopping motion blur of a moving subject, diffusion for softer illumination, and other modifications of the light.  This class covers all types of flash units, from a camera’s internal flash to hot shoe mounted external heads as well as off-camera studio strobes.