Spring is the time of year when our photographic fancy may turn to birds. Our feathered friends are everywhere; on the lawn pulling up worms; perched in flowering trees and bushes singing their hearts out or chirpingly setting up nests for prospective offspring.

Many of us have thought about picturing them and wondered what it takes to capture their image. Which camera, lens and film and what specialized techniques to use.

The best camera is definitely the SLR (single-lens reflex) because it has the adaptability of being fitted with telephoto lenses and, by focusing through the lens, offers a sharp image.

The best lens is a 200-mm telephoto on a 35-mm reflex camera. Shorter focal length lenses will not give enough enlargement while the longer teles are too slow to stop movement or provide a large enough lens opening to photograph in poor light or shade. (My favorite lens is the 200-mm f/4 Nikkor, which has sufficient depth of field to shoot at maximum aperture. But there are many lenses in the 200-mm to 400-mm category that will do just as well).

Fast film is a must, as birds are usually most active in the early morning or near dusk, when the light is dim. The faster emulsions such as Ekatachrome High Speed at ASA 200 or the Ektachrome super fast 400, or their equivalent in other makes, are the best. These films will also enable you to stop the quick jerky action of heads and tails.

Techniques can vary widely; some are simple and others extremely complicated. The choice depends on your energy, interest and time.

The most obvious and easiest for the backyard photographer is to focus on the feedbox or the nest. A bird feeder can be set up near a convenient window or you may be lucky and have the bird family set up housekeeping in a nearby tree. The trick to shooting these from-behind-the-window scenes is to stay back in the shade (you can pull the drape or blind, leaving an opening for the lens while you stand back out of sight).

Set the camera on a tripod, as the wait may be a long one. Prefocus on the feedbox or nest and wait for your quarry to come. Then, with your pre-set shutter speed and lens opening, shoot quickly. (Set your tele lens one stop down for sharpness and adjust the shutter according to the light).

Better photos can be taken with a flash or electronic strobe. (The strobe is best because you can take repeated exposures without changing bulb). Position your light unit mounted on the tree or near the bird feeder. The light can be connected to your camera by means of a long synch cord (available in various lengths that can be plugged together). If you use such a flash on an extension, be sure to figure the exposure distance from the flash -- not the camera.

If you are really in luck and have either a nest or a feeding station right outside your window within a short distance, such as five feet, you can use the flash on the camera right through the window. The trick is to shoot at an angle to the pane or press the lens right up against the glass.

Field techniques for bird photography involve the use of blinds. These need not be complicated -- any tent-like setting will do so long as it can be further camouflaged with branches and leaves. It will take some time for the birds to get used to the intrusion, so be patient. Start by placing the blind at a distance and gradually, day by day, move in closer. If the birds are shy and you don't want to sit inside the blind for a long time, you can employ a trick. Go inside the blind with a friend and after some time have your companion leave. The bird, not having completed a math course, may figure that you've left -- which leaves you one up and the bird thinking the blind is now vacant.

Although I've not been a fulltime ornithological enthusiast, there have been occasions on assignments when I've ended up bird-watching through the lens.

One exotic experience was in the Antarctic, where I had the chance for eyeball-to-eyeball closeups of baby Emperor penguin chicks. I accompanied a field expedition via helicopters to observe a flock of these giant snowbirds. We were in luck -- some adults were baby-watching their giant offspring. The three-foot-high, 20-pound fledglings were quite friendly. Members of the party were able to chase them down and pick them up at will while the indulgent parents looked on. (We were cautioned not to try to pick up the adults because a flip of their wings could break an arm or leg).

Another time in the Caribbean I was put ashore on an uninhabited island to picture the nesting seabirds. I spent the day clambering among the prickly growth photographing pelicans, cormorants and egrets. It was hot and sweaty work, but I kept at it to make the most of the daylight hours. Actually, I could have taken it easy because a storm arrived and it was three days before the craft could return to take me off my Robinson Crusoe island.

Anyone can take good photos of birds if the conditions are right, but if you want to go for the real ornithological adventure and become a bird-watcher extraordinaire , you need sophisticated equipment.

Extremely long telephoto lenses of 500 to 1,000 mm, photoelectric trip lights and radio-controlled cameras have been used by top pros. Others have invested countless hours of frustration sitting in a wet blind having a dry run of exposures. Still more have turned steeplejack and shot from platforms set in towering trees to capture elusive eagles on film. Q. What kind of camera should I buy or rent to take a really clear 35-mm transparencies of some pen-and-ink and watercolor and oil paintings? These works range in size from 3" x 5" to 18" x 24". I suppose that some could be lined up and shot at once. Is flash best or daylight? I don't want any shine and they must be good enough to be published . A. First off, I would advise you to check with your publisher, because very likely it would prefer the originals that can be sent to the engraver for direct copies. A 35-mm copy, at best, is a poor substitute.

On the other hand, slides may be adequate for editorial choice. In that case any 35-mm SLR (single-lens reflex) camera will do if it has a lens that focuses as close as 18 inches (approximately). The reason to use an SLR is so you can move up for a large image.

The best lighting to use is outdoors in the open shade or in direct sunlight with the angle of the light from about 45 degrees to the right or left of the camera position. In this way you can avoid glare.

You won't need a tripod in outdoor light as you can shoot at about f/8 at 1/125th of a second with average color slide film such as Kodachrome 64. What you will have to watch is to keep your camera position with the center of the painting at lens height and the camera back parallel with the work itself. (You can use the same slide film for the black-and-white sketches as well).

The easiest setup is to use an easel and set the painting on it at camera height, then move back and forth to adjust the size of the image. Be sure to focus very carefully on the surface of the painting so that the resulting copy is sharp.

The best way to send the slides by mail is registered with a return receipt requested. The registration (actually, certified mail is just as sure) will give you a record if lost and the return receipt will assure you of its safe arrival.

The yellow pages of your telephone directory will give you a choice of photographers whom you can call. Be sure to explain your needs. Specify that you want 35-mm color slides and the approximate number of copies you need. Obtain several estimates and compare before authorizing the work.