An external flash is geared for photographers who want to stay mobile. They usually capture fleeting moments such as at press conferences or if you are at a “Live” event. An external flash can also be used to add dramatic lighting to more contemporary-styled portraits.They are light-weight, compact, and less expensive than a studio lighting kit.
External flashes tend to cast a harsh, less subtle light to a scene. They also have a very limited range in how much a scene is illuminated. A diffuser can be used to soften the harsh light, though this cuts down the range of the flash even more.