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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.
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.
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.