The Ray Flash is portable and lightweight, and has been designed to take advantage of a camera"s TTL metering capabilities. Because the Ray Flash relieson the hot-shoe flash to generate its light, it contains no electronics, no flash tubes and requires no cumbersome cables.The light distribution is accomplished through a sophisticated system of internal prisms, reflectors and light-shapers designed to distribute and project the light evenly around the lens.The Ray Flash creates a unique ring flash lighting effect: a three-dimensional shadow-wrapped look around the subject. Because ring flash light originates from a circle around the lens, it produces a virtually shadowless look on the front of your subject, while producing a soft even shadow around the edges. The versatile Ray Flash is ideally suited for fashion, wedding, portrait, journalistand macro photography as either a main or fill-in light.Exposure control:All TTL functions operate normally when using the Ray Flash. As with standard flash use, manual exposure control requires the use of a light meter or test-shots.The Ray Flash is designed to fit the Canon 580EX (MKI & MKII) and Nikon SB800 flash units. Weighing about 16 oz, the Ray Flash is lightweight and is easily supported by hot-shoe mounted flash units. The 4 1/8" internal diameter of the Ray Flash is large enough to accept almost all professional lenses from Nikon & Canon. Light output:The Ray Flash results in only one stop of light loss from your flash"s standard output. The Ray Flash does not change a flash"s color temperature.How to fit the Ring Flash Adapter: Mount the Ray Flash to the front of a portable flash unit by sliding the Ray Flash over the front of the flash unit. Then turn the lock on top of the Ray Flash to hold the Ray Flash firmly in place. The Ray Flash requires no modifications to your flash unit to mount.