LIKE tanning freaks, home- builders and daffodils, photographers tend to be happiest in the sunlight. But if rainy days keep you homebound, you're missing some good photo opportunities.

The biggest roadblock isn't a fear of catching cold, but of soaking expensive hardware. But for the price of a normal lens, you can pick up a plastic underwater housing at a scuba-diving shop. If even that modest price is too much, you can make your own (above- ground only) housing from a plastic lunch bag or wastebasket liner.

Place the camera, with lens attached, inside the bag; cut a hole for the lens and viewfinder and tape the bag with gaffer's tape to the viewfinder's rim and the lens hood.

If your camera doesn't have a motor drive, poke a small hole for the film-advance lever, too. Pull the bag snugly against the camera by tugging down on the open end, then secure it with a garbage-bag tie for shooting. To change film or lenses, just remove the tie and reach in.

The resulting rig won't win any awards for speedy handling, but it's better than a drenched camera.

Make sure your lenses are fitted with good lens hoods and skylight or UV filters to keep them dry. Carry a couple of spare filters in your bag so you can exchange them quickly, instead of having to dry one off before you can take your next shot.

Carry a soft chamois cloth to use when the inevitable happens -- it's more efficient on a wet filter than either your shirttail or a lens tissue.

Changing lenses and film in the rain can be tricky, but it's less so if you wear a poncho with a fisherman's vest underneath. The vest's pockets can hold spare lenses, lens caps and film enough to allow you to do your changing under wraps.

No matter how cumbersome the logistics, rainy-day shooting has its rewards. When it rains, light has a soft, shadowless, omnidirectional quality, subduing textures and depth. Subjects acquire a bluish monotone; colors are desaturated, or lacking in "snap."

Just as the smallest fingerprint will be eye-catching on a freshly painted white wall, so will be small bright patches of color in the subdued palette of a rainy day. Such swatches show up in neon street signs or the colorful umbrellas or rain slickers of passersby.

You'll find, too, that colors will lose saturation at greater distances from the camera. One way to restore a sense of "depth" in your photo is to include an important foreground object, which will appear relatively unaffected by mist.

A soft, misty feeling can be enhanced by using a high-speed, comparatively grainy film such as Ektachrome 200 or 400. For an even grainier feeling, shoot those same emulsions at a one-stop-higher exposure index and have the lab "push process" the film. If you're a color negative fan, the grain and contrast inherent in Kodak's VR 1000 should fill the bill. If you're heading out with black-and-white film, you'll have to increase development time about 10 to 15 percent to boost contrast levels, so the flat light of the day will print well in the darkroom.