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Many cameras now have a built-in flash that is used to take pictures inside when the light levels are low. Most cameras will have an Auto mode and there are usually several other modes including, Red eye reduction, Off, On, Slow sync.Most SLRs and some compacts have the option of attaching an external flash on an accessory shoe. Some have a sync socket so you can attach a studio flash off the camera for more controllable results. Buying advice: The flash range is often quoted and ones with more power will allow well-exposed pictures to be taken at greater distances. Having several modes increases the camera's versatility. If you would like to use studio flash you can fire heads remotely using your camera's built in flash and a slave unit, but watch out on digital cameras - the flash may not be synchronised correctly. It's better to use a camera with a sync socket. The most useful feature of an auto camera is Flash Off so you can avoid flash when you want to shoot in low light and Flash On to force the flash to fire to get good fill-in light in contrasty conditions.
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Many cameras now have a built-in flash that is used to take pictures inside when the light levels are low. The camera detects when flash is needed and automatically fires it, there are usually several other modes to increase the flash's versatility. Red eye reduction fires a pre-flash to prevent large red eye pupils appearing. 'Off' turns an automatic flash off so that the camera can be used with a long shutter speed for night photography. 'On' forces the flash to fire as a fill-in for daylight pictures that have harsh shadows or to illuminate a close subject in a night scene. Slow sync fires flash and records the ambient exposure, which is great for creating image trails and creative subject movement.
Flash units often have a range of settings that controls the amount of flash emitted. With portable on-camera flash this is normally controlled automatically by either the camera or a sensor on the flashgun. Studio flash are often less sophisticated and have a slider or switch offering half or quarter power. Some of the more expensive models can be adjusted more accurately though a greater range of stops.
A studio flash unit that has its flash tube and charging circuitry all contained within the head.
Where the shutter is held open and the flash is fired manually. This allows you to fire a smaller powered flash several times to ensure either a large area is covered or a single area receives enough exposure a technique known as painting with light.
An electronic flash has a maximum distance that it is capable of illuminating. There's also usually a close point where it will start to become too bright and overexpose the subject. The distance from the closest to the furthest point that it can illuminate is the flash range. The range can be increased by using a faster film or more sensitive CCD, and reduced by diffusing the light source using ND filters or material. The range quoted is usually based on using ISO 100 film or a CCD with equivalent sensitivity. APS cameras are, for some reason, quoted using ISO 200 film.
The maximum shutter speed that can be set when using electronic flash. You can use shutter speeds below this setting but ones above will make some of the picture dark because the shutter would have partially closed before the flash had fired.
A socket on the camera used to plug-in an electronic flash gun cable so that the flash can be triggered at a distance from the camera.
A flash technique where you fire the flash several times to increase the exposure allowing a smaller aperture to be selected. It can also be used for special effects; the most common being strobe like effect, following the swing of a golfer or the flapping wings of a nocturnal bird. It can also be used to light the same subject in several positions in the frame - to allow a multiple exposure effect.
A portable flash gun which can be coupled with an automatic camera and can then be controlled by the camera's programmed functions.
A way of reducing harsh contrast by adding light to darker or shaded areas of the subject using a reflective material or flash.
A time measure taken from a flash between it reaching 50% of its peak value to the point when it has diminished to the same value.
A meter used to measure the light that is emitted from an electronic flashgun. The meter suggests what aperture should be used to obtain a correct exposure. Some meters are purely for flash, others are multipurpose.
If you've ever taken a photo in low light using a compact camera or an SLR with built-in flash you will have no doubt come across a strange effect - people with alien-looking eyes. The reason is simple; the flash lights up all the blood vessels in the eye which reflect back into the lens. The further away the flash is from the lens the less likely the chances of this strange phenomena occurring. The problem with built-in flash is that you can't control where the flash fires from. To overcome this, many cameras have a red-eye reduction mode, but it is, as the name suggests, only a reducer. It works by firing a pre flash to reduce the size of the pupils, and in doing so reduces the area of red. The redness is still usually apparent, but because the pupil is smaller the effect is less noticeable. There are three methods used in cameras to reduce red-eye. One is a single pre flash. This is quite bright and can fool the subject into thinking the picture has been taken. So you avoid red-eye but have a picture of a person either looking away or blinking. The second method fires a less powerful, but equally distracting, sequence of flashes, almost like a strobe. This can result in the unaware person shielding their eyes from the potential epilepsy inducing strobe! Version three tends to be the most subtle - a torch-like light that shines for about five seconds before the flash is taken. The only downside of this is battery drain. If you have a computer you can remove red-eye digitally using image editing software. If you don't there are special pens available that you can use to colour in the red on your photos.
Indicates the energy content of the storage capacitors in an electronic flash. One Joule is the light output given by one watt burning for a second. Therefore a flash unit with a storage capacity of 300 Joules can supply the power to light a 300W lamp for one second. It doesn't take into account any electrical loss between the flash capacitor or flash tube, or the efficiency of tube and reflector.
A light that is positioned close to an electronic flash so you can roughly preview the effect of the flash before taking a photo. Usually supplied with studio flash although a few on-camera guns have a strobe to assist.
A type of camera flash synchronisation, found on more sophisticated SLR cameras, that fires the flash just before the second shutter blind closes. It’s used with slow shutter speeds to photograph moving objects. As the movement will be blurred before the flash freezes the subject it appears with a trail behind it. Use normal front curtain sync and the trail will appear unnaturally in front of the subject, making it look as though it is moving backwards.
A flash accessory, also known as a slave cell thats used to fire another flash remotely so that multiple flash set ups can be arranged without cables and all synchronised with the cameras shutter.
A metal pole that attaches to a lighting stand and holds a flash head at the end. A counterbalance weight is also usually used. This is used to get the flash closer to the subject as well as over or under it.
Indicates the output, or power, of an electronic flash. You can use the guide number to work out the aperture or flash to subject distance by dividing either into the guide number.
A flash sync connection found on some older cameras that was used for bulbs, not electronic flash.
The time it takes for an electronic flash to fully recharge. Automatic thyristor flashguns have special circuits that store unused flash ready for the next shot so recycling speeds up. This is essential for fashion and sports photography, but less so for still life. The recycling time of more powerful or manual units is usually longer.
A box with a diffuser panel that attaches to the front of a flash to give soft even light. Any visible highlights such as catch lights in eyes, reflections in silverware will be neat and square. Bigger ones give more surrounded and even light but absorb more light so are best used with powerful flash heads.
A term used to describe a combination of sunlight and flash light, where flash is used as a fill in.
An electronic flashgun feature that allows the flash coverage to be adjusted. Flashguns are usually designed to cover the same angle as a standard lens, so when a wide angle lens is used you may find the edges of the frame are darker. A zoom head pulls closer to the flashtube to widen the angle and extends to throw the flash light out at a more concentrated angle.
Light that is reflected off a surface before reaching the subject. Flash is often bounced off a ceiling or card to soften the result. Reflectors can be used to bounce light into shadow areas to reduce contrast.