For the occasional shutterbug, photographing children can be an exasperating experience. But for a few photographers, it is a labor of love, and their work is recognized as art.

Shelley Langston of the Langston-deVincent Photography Studio in Georgetown is such a photographer. She has been photographing children for over 20 years, has written four books on photography, and taught a course at the Smithsonian on photographing children.

Her studio walls are lined with photos of children which are classics in design and composition. She is committed to her art and believes that it can't be taught easily.

"When I take pictures of children," she says, "I try to show who they are.

I focus on feeling.It's not necessary to worry whether or not the child is smiling."

This belief is echoed by other fine photographers, such as Monte Zucker of Monte Studios in Silver Spring.

"After all," he asks, "how many portraits of children do you see in museums where the child is smiling? In a portrait, the most important thing is expression."

Wayne Hill of Hill Photography in Potomac concentrates on capturing what he calls "the themes of childhood." By this he means remembering that childhood is a time to be playful or mischievous, a time to be inquisitive, and a time of dependence.

"Such moments don't last too long. I work on capturing them on film."

Photographing children presents unique challenges. Since a child's attention span often is very short, the photographer must be quick.

"With children," says Langston, "I have to work very fast. It might be easier to get them to relax, but to take a good picture at all is the difficult part."

Many children equate visiting a photographer's studio to going to a doctor or dentist, so allaying their fears also is a part of the photographer's job. Langston tries to relax a child by taking walks with him, playing music, or playing with toys.

Hill says that sometimes he must spend a great deal of time trying to establish rapport with a child. He finds that stooping down to the child's level, along with whispering, will help. His graduate studies in psychology, he says, are of more help to him than he ever dreamed they would be.

Zucker employs an ingenious method of relaxing children. He tells them that since they are always taking candy from their mothers, it is now their turn to give candy to them. He then photographs the proud look of the child just after handing the candy to mother and watching her eat it.

What separates the professional photographer from the amateur, besides mastery of the camera and equipment, is in knowing the precise moment to react and take the picture.

"You have to know when a moment has occurred which is more profound and exciting than others," says Langston. "This is what Cartier-Bresson called 'the decisive moment.' My job is to help the child create such a moment and then see it and record it."

The most difficult children to photograph are those who have been endlessly instructed by parents to pose and smile, or children who have stood in line for a photographer in a quick-picture setting.

Parents' involvement?

"Sometimes I use the parents, but sometimes I send them away. Each case is different," says Langston.

Zucker relates instances where a parent actually has slapped a child to make him behave in front of the camera. "Naturally, that ruined the entire sitting."

Photographers of children, of course, can expect situations which normally wouldn't occur when photographing adults.

Hill displays a charming picture of two lively brothers standing beside a tree. The picture was taken as they were smiling, and it was the last frame in his last role of film. After he snapped the picture and turned away, he heard one boy crying, accusing his brother of hitting him.

When the pictures were developed, the intention of one of the smiling brothers is caught on film: His fist is clenched and his arm is already in motion, ready to strike.

Professional photographers are often reluctant to offer much advice to parents on the technical aspects of photographing children. They have mastered their camera and equipment, so use of them is routine.

"The only way to freely unleash your creativity is to be thoroughly skilled technically so you can concentrate on the subject, rather than technique," says Zucker.

Langston advises parents not to become too enamored with equipment. "You can take a good picture with a Brownie camera if you know what to look for."

The philosophy behind judging a good portrait of a child is basically the same as evaluating any photo. The photograph should not contain distracting backgrounds or clothing. Good photographers strive for simplicity.

"A photo is a language and the statement spoken should be short and simple, and hit you right between the eyes," says Zucker.

Bethesda photographer Wendy Saunders says that "children, as subjects, are almost always photogenic."

Adds Hill: "Children are spontaneous and unpredictable. That's what keeps it challenging and interesting."