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Light is the single most important factor of photography, in fact, the word photography itself comes from the Greek language and translates into 'drawing with light'
. Using flash can make all the difference in getting the light correct
Built-in flash is a function which features into all modern-day compacts and many DSLR's, and without it, many variations of photography we know today wouldn't be possible. Flash involves a delivery of electronic light to illuminate a scene as the shutter release is activated, and is used for situations when the level of available light is very low, or when there is a high contrast between bright light and shadows. Different types of flash are necessary for different types of lighting conditions, and most cameras offer several options as to which you can choose. Here's a summary of the most popular types of flash and in which situations you would use them.
Without use of flash, the background is recorded corectly but the subect is dark.
| Slow-Synch flash records the background and then illuminates the subject with flash to balance the exposure between the two areas.
The most common type of flash in which the camera detects low light levels and fires the flash automatically.
Will fire the flash regardless of the available light, handy for use in outdoor pictures when there may be darker shadowed areas but generally the lighting is good.
Turns the flash off completely - Used for when flash photography is not permitted, such as in museums, or required, for example, well available light levels are sufficient.
Slow-sync mode activates the flash when using slow shutter speeds and is useful for balancing the light between background and subject, and so is often used in night time portraits.
Fill-in Flash is weaker than regular flash, but is strong enough to add light to darker areas of the image such as shadows. This is useful for situations when the subject needs illuminating but the background doesn't, or when daylight alone casts shadows onto a subjects face.
| Without use of flash, the subject is dark, and the only part of her highighted by the sun is her right shoulder.
This shot, taken with use of the fill-in flash, brightens up the areas of the subject that were previously shadowed by the sun.
Flash with red-eye reduction
Flash often causes red eye in subjects by lighting up the blood vessels in the eye.
Red-eye in subjects can often be a problem in portraits taken with flash. It's caused by the flash lighting up the blood vessels in the eye which are then reflected back to the lens. This is a particularly common problem when subjects are close to the lens. Most cameras have some kind of built in red-eye reduction system which is usually a single flash shot, a sequence of flashes, or a more prolonged and less distracting light before the main flash is fired. This works by reducing the size of the pupil prior to the picture being taken. Another way to get rid of red eye is to remove it digitally afterwards in a program such as Photoshop, or avoid it in the first place by getting the subject to look slightly away from the camera.
While low light scenes are most often the reason for using flash, it can also be used to more creative effect to freeze the action of a moving object, or to create a different temperature of light than that provided by the scene itself.
Sometimes there is a need for additional flash to be used other than that built into the camera, such as in studios. Studio flash is more powerful, recharges faster, and is more flexible, but more expensive than on-camera flash.
Sometimes the built in flash will be too weak for the subject for example, if the working range is 3m but the subject is 5m away, a separate flash unit may be required. These attach to the hotshoe of the camera (see image below) and are much more powerful.
Separate units called a flash gun attach
to the hot-shoe of the camera for more
© All images copyright of Duncan Evans except picture 5.