Built-in flashguns come in two basic varieties. The most common type found on nearly all compact cameras is simply built into the front of the camera, usually in the corner above the lens, with a clear plastic window over the front of it. These are usually very close to the lens, which can cause problems with red-eye on close range shots of peopleâ€™s faces.
The other common type is the pop-up flash, found on many super-zoom or high-end cameras, and nearly all DSLRs. The flash is mounted on a sprung, hinged panel that flips up when activated. The main advantage with this type of flash is that it positions the light source further away from the lens, reducing the occurrence of red-eye. Pop-up flashes are also often a bit larger and more powerful than the internal type.
As well as built-in flashguns, there are several other types in common use. The one with which youâ€™re probably most familiar is the camera-top external flashgun. Many higher spec cameras such as semi-pro and SLR models have a mounting bracket usually situated on the top of the camera, called a â€œhot-shoeâ€. An external flashgun clips into this bracket, which includes electrical contacts which allow the camera to trigger the flashgun and in many cases also allow the flashgunâ€™s light output to be controlled by the cameraâ€™s exposure meter. Flashguns that can connect to a particular camera in this way are called â€œdedicatedâ€.
Some cameras designed for professional or enthusiast use have a second flash connection called an â€œx-sync socketâ€. This is used for connecting external flash units that are not mounted directly on the camera, such as studio flash systems. It is usually a simple electrical switch linked to the shutter, and does not allow the flash to connect to the cameraâ€™s exposure meter.
For cameras that do not have an x-sync socket, a small adapter bearing an x-sync connector can be fitted to the hot-shoe, which allows the camera to be connected to an external flash. Rummage through the side pockets on any enthusiast photographerâ€™s kit bag and youâ€™ll be sure to find at least one of these.
Hot shoe brackets are mostly of a standard size, so most flashguns will fit most cameras that have one, although the metering connections are not standardised, so a flashgun dedicated to one particular camera may not work fully with another. One exception is (unsurprisingly) Sony, which inherited the Dynax flash hot-shoe from Minolta. This is non-standard, and only Dynax-fitting flashguns can be used.
Another type of flashgun, especially popular with professionals such as press photographers, is the â€œhammerheadâ€ type of external flashgun. This is mounted on a bracket that attaches to the tripod bush on the underside of the camera, and is usually powered by a separate battery pack.
The main advantages of this type of flash are superior power, much faster cycle times and reduced red-eye at close range, since the flash head is further from the camera lens.
An less common type of camera-mounted flash is the ring flash. Originally designed for dental and forensic photography, it is often used by fashion and portrait photographers for its even shadow-free coverage. It usually consists of a wide circular flash tube mounted in a reflector that fits around the camera lens, although some types have a series of smaller individual flash tubes mounted around the lens.
Ring flash units are especially good for macro and close-up photography, because they can light a small subject from all sides, without the problem of the camera lens itself casting a shadow.
Professional studio photographers use special mains-powered flash units, typically using two or more lights to achieve particular lighting effects. Studio flash heads are usually used in conjunction with a range of reflectors, diffusers and other accessories that help the photographer to precisely control the direction and appearance of the light. Studio flash units are connected to the camera via the x-sync socket, a hot-shoe adaptor, a slave flash unit that uses a high-speed photocell to trigger a secondary flash when a primary one fires, or in the case of some modern professional cameras, via a built-in wireless connection.
A good quality beginnerâ€™s studio flash system neednâ€™t be prohibitively expensive and will massively improve your portrait photography. Something like this Interfit EX150 kit is only around Â£220.