Whether you're a camera buff with a fancy camera, several different lenses and a fully-outfitted camera bag, or an occasional snapper with a prefocused pocket camera, winter presents photography challenges.

Foremost, light conditions, with the sun reflecting a thousand ways off the snow, or the flat light of dreary, cloudy days.

Light meters on most cameras are averaging meters - they measure all the light coming in and give you an averaged reading; they don't select for any specific thing in the viewfinder. That's fine if you're shooting scenery, but it can play havoc with closer shots of friends or family in the snow. If you don't compensate, faces will be underexposed.

The best way is to set your shutter speed based on the reading you get off your subjects face. Walk right up to your subject and let your camera read only his face. While that might overexpose the snow in the background, it doesn't make too much difference since it is all white anyway.

You can also use a slower film on a bright day - ASA 25 instead of ASA 100, for instance, even with a prefocused pocket camera. Many can handle more than one film speed. Check you camera store of your instruction manual.

Or you can use a flash. With a prefocused camera, just pop in the flashcube; with an adjustable camera, set your exposure without the flash and use the flash to fill in light on the face. It will not make enough of a difference in the background to affect your photograph. Consult your manual to make sure your shutter speed is synchronized properly for the flash.

On flat, gray days you need faster film and a wide aperture or slower shutter speed. If your camera is adjustable, you might open the shutter a little. If your camera is prefocused, you might be able to do the same thing by using a burned-out flashcube. Putting a flashcube on some prefocused cameras signals them to take pictures at a slower shutter speed.

Another winter problem is taking pictures of fast-moving winter sports like sledding or skiing. A skier or sledder can whizz by you only so many times before one of you gets too cold to continue.

Your best bet is to position yourseIf below the subject at a 30- to 45-degree angle to his track at the point where you want to take your picture. That way you have him in your sights long enough to take a good picture, yet you do not have him moving directly toward you growing larger and getting closer all the time, requiring you to continually adjust your focus.

If your lens is adjustable, stop it down as far as you can (to f/16 or f/32 if you can) to get the greatest depth of field and to give you some leeway in focusing, but do not stop it down so far that your shutter speed has to be less than 1/125th of a second or you won't be able to stop the action. If you have one, a wide-angle lens also increases your depth of field.

If your camera is prefocused, your picture will come out better if you get farther from your subject. This allows the camera to use its entire focusing range, and gives you a better chance of framing a moving subject.

To get a feeling of motion in your photographs, you can pan the camera to follow the skier or sledder, or fix the focus on a particular spot and snap the picture as the subject reaches that spot. If you pan the camera, the subject will be clear and the background will blur, if you focus on a spot and wait for the person to get to it, the background will be sharp and the subject will blur with speed.

You don't have to limit exciting winter photos to the outdoors. Some of your most memorable moments are in front of a roaring fire, and it is possible to take available light pictures with an adjustable focus camera. The problem with fireplace pictures is that it is almost impossible to get a meter reading.

Follow these guidelines: with ASA 100 film use f/4 at 1/30th of a second; f/2.8 at 1/60th of a second; with ASA 25 film, use f/2 at 1/30th of a second, f/1.4 at 1/60th of a second. (Since cameras and situations vary, bracket your exposures - take three shots at each shutter speed, using the suggested f/stop, and one slower f/stop and one faster to be sure that one is exactly right.) These settings will let you get the fireglow and its reflection on the faces of those sitting close. It is a nice, warm looking picture - just the thing for cold, wintry days.