In the early days of photography, low-light pictures were a challenge for photographers. For flash pictures, the light from the flash had to be extremely bright - often blinding the subject for several seconds. For natural light pictures, the exposure had to last several seconds - which is why subjects who moved looked blurry.

Today, low-light photography is almost as easy as shooting on a sunny day - thanks to improved films and flash units.Fast films - ISO 800 and 1000 - are more sensitive to light than slower films. This means you can shoot at a faster shutter speed and smaller aperture than if you were using ISO 200 or 400 film. The benefit? You often don't need a tripod to steady your camera (due to the fast shutter speed) and you'll get more depth-of-field (due to smaller aperture). The result is sharper pictures in low-light conditions. Faster films have more grain than slower films. The increase in grain, however, is often not noticeable even in a 5-by-7-inch print.

During the past two years, fast slide and color print films have been introduced that offer better color and contrast than previous films. What's more, the new generation of slide films can be pushed (exposed at a higher ISO rating) with only a minimal increase in grain. In fact, when some of the new ISO 200 films are pushed to ISO 400, the increase in grain is hardly noticeable.

When you are photographing people and pets in low light, make sure that the brightest part of your scene is your subject's face - unless you are taking a silhouette.

Flash units and camera circuitry have also been improved. Many modestly priced point-and-shoot cameras (as well as high-end cameras) offer through-the-lens flash metering, so you get a good flash exposure in most situations.

There are, however, times when some flash metering system can be fooled. When your subject is wearing white, the camera may think that the subject is brighter than it actually is, resulting in a lower flash output and an underexposed picture. The remedy is to increase the exposure by about one stop (this is only necessary when using slide film; color print film has a wide exposure latitude to compensate for the underexposed image.)

Spot-lit subjects, like a child standing on a stage at a school play or a musician playing on a sound stage, can also fool a camera's meter into thinking that the scene is brighter than it is in reality. Filling the frame with the subject will prevent an underexposed picture. So will setting your exposure for your subject - and not the entire scene.

The camera's flash metering system can also be fooled when the subject does not fill the frame - because in low-light situations the camera will think the scene is darker than it actually is. This will result in an overexposed picture. The remedy, again, is to fill the frame with the subject.

So for low-light photography, follow this tip: Use fast film and always have fresh batteries for your flash.