What does a flash on a camera do?

Answer 1

Old flash bulbs contained a lot of jumbled tungsten, zirconium or aluminum wire housed in an oxygen atmosphere that was rapidly burnt when the shutter was clicked. Early amateur cameras supplied the current by battery. Later, simple point and shoot cameras like the Kodak Instamatic used something other than a battery (probably a piezoelectric device like a barbecue starter, but I'm just guessing). The bulbs were blue coated to balance the light for color film, and some contained a blue dot to indicate the oxygen had not leaked out and been replaced by air. If an air contaminated bulb was used, it usually exploded.

Some cave photographers prefer the flash bulb to an electronic strobe, claiming the quantity of light output is superior. However, bulbs are getting harder to find.

Answer 2

Flash can make or break a picture. There are so many possible effects of flash that it's hard to answer. There are times when the only way to get the picture at all is to use flash. Most cameras made today, including disposables and point-and-shoot digitals are equipped with tiny electronic flash tubes (we used to call them "peanut" flashes) that are positioned very close to the lens. The downsides to this include "flat" lighting because the angle of the flash (the four-dollar term is "angle of incidence") is right over the lens, and "red eye," which is actually a reflection of the blood vessels in the retinas of your subjects' eyes. On the other hand, if you're at a party in a darkened room and you're trying to grab a quick shot of a moving target (think dancing), flash may be your only option. Flash does have the advantage of being able to "freeze" motion because electronic flash happens very fast.

Many of the little point-and-shoots do give you some control over flash, however. One of the most useful is outdoors in bright sun. But why would I need a flash? There's plenty of light! But when you take the picture without a flash, there are often objectionably deep shadows. Your subject's eyes may be in shadow. One side of the face may be lit by the sun and the other is nearly pure black in shadow. But if you turn your flash on (and you're close enough for it to do some good) the flash illuminates the shadows and opens them up without having any visible affect on the highlights. Or, say your subject is backlit (sun coming from behind the subject). Turn your flash on. Some of least sophisticated point-and-shoots even have a special flash fill setting for these situations.

On the other hand, a flash can completely ruin a picture. For example, try taking a flash picture of yourself in a mirror. All you can see is the flash. This is because of that angle-of-incidence thing we mentioned before. The flash is right over the lens so the light from it bounces right back into your lens and washes out everything else.

But check your camera manual and find out what sorts of options you have for the use of the flash. Some cameras have a "party" mode, which kicks the ISO up to capture some of the existing light, plus squeezes out a little flash to illuminate your foreground. If you have a more sophisticated camera with a hot shoe, you can get a flash unit that has a swiveling head so the light can be "bounced" from a ceiling or nearby wall. If you have a second flash unit and what we call a "slave trigger" that responds to the flash on the camera, you can set up multiple lights and go nuts. This can't be explained easily in words and requires some training and experience. Flash is a tool. It can be great or not so, depending.

Answer 3

A camera flash provides a brief intense light to allow a picture to be captured when it would otherwise be too dark. They can also be used to provide light from a controlled direction to fill in shadows left by other light or achieve other effects.

Early flashes used a chemical reaction to provide the light, originally in trays of loose powder and later inside single use glass bulbs. Modern flashes typically use a tube of zenon gas. When an electric arc is passed through the tube light is released. LED based flash are used in some mobile phone cameras. Modern flashes are reusable and are often built into cameras.

Answer 4

Takes clearer pics in darker places, stops ugly shadows, and freezes action.