With a camera, imagination and considerable dark-room skills, three Pittsburgh men captured childhood's passages and carefree dress-up days that not only recorded early Pittsburgh life, but also showed how photographs were created to mimic painted portraits.

"Picturing Childhood," a Carnegie Museum of Art exhibition that runs through Jan. 13, showcases 40 elegant black-and-white photographs created by these amateurs from three overlapping generations spanning the 1800s to the mid-1900s.

Their work and the show, which also includes images from professionals who were led by Alfred Stieglitz, illustrate an era when some of the world's best photographers promoted their work as an art form comparable to painting. From 1885 through 1914, devotees of pictorialism experimented with soft focus, dramatic lighting and exotic printing process and spent innumerable hours in the dark room manipulating their negatives and prints to achieve personal artistic expression.

"The word pictorialism was chosen to reference painting," said Amanda T. Zehnder, assistant curator of works on paper at the museum.

Pictorialism influenced the three local amateurs, Charles Hart Spencer, Charles Henry Breed and Walter Francis Munhall, whose work helped establish conventions of the family photo.

All three "were incredibly serious about it as a craft. They did personal research and invested in it," Ms. Zehnder said.

Mr. Spencer and his wife shared their Victorian home with seven children in Shadyside; their daughter, Ethel Spencer, recounted their lives in a memoir called "The Spencers of Amberson Avenue."

A salesman for Henry Clay Frick, Mr. Spencer compelled his children to dress up for camera sessions and lined them up from oldest to youngest.

"The children apparently didn't like that so much. They found it tedious," Ms. Zehnder said.

Mr. Spencer, who died in 1912, snapped a memorable picture of his first grandson in a basket-style baby carriage with gigantic wheels. Dressed in an elaborate white outfit with a frilly hat, the baby boy pops against a gray background; the image is equally amusing and sentimental. An outdoor portrait of the Spencers, with the women in frilly, long-sleeved blouses and floor-length skirts, oozes Victorian.

In 1900, Mr. Spencer made a small cyanotype in vibrant blue with white highlights. The image of his twins, Charles and Elizabeth, Ms. Zehnder said, "shows that Spencer was willing to work with more complicated techniques."

Mr. Breed, who also lived in Shadyside, was born in 1876 and died in 1950. He recorded his methods for taking specific pictures in a red diary he kept during a trip to Paris with his family in 1910. The diary and some of his equipment are exhibited in the first gallery.

Mr. Breed's images of his daughters, Ann and Elizabeth, are formal portraits. In one image, captured on a porch in 1911, the younger child has drawn her right hand up into her dress sleeve, a sign that she may be weary of standing still for her father.

While the Spencers and Breeds enjoyed upper-class living, Mr. Munhall struggled to get by during the Depression in Hazelwood. After he became head engineer for Pittsburgh's water department, he bought a Leica, considered one of the best cameras of its day. From 1938 through the late 1940s, he photographed his sons, Walter Jr. and Edgar.

An especially memorable image is Walter Munhall Jr., dressed in a cowboy outfit, pointing a gun and looking straight at the viewer with an air of confidence that John Wayne would have loved.

By contrast, a photo of Edgar Munhall, dressed in a sailor shirt and sunglasses, conveys the cute goofiness that is part of childhood.

Edgar Munhall, now an art historian and a curator emeritus at The Frick Collection in New York City, said each photographer in this show "had his own voice."

His father's Leica, Mr. Munhall added, was called an immigrant's camera because the equipment was among the few treasures people fleeing Germany in the 1930s could carry with them.

"The Leicas were relatively new and high-tech," he said, adding that his father studied engineering at Penn State and that photography was among his constant interests.

He is rather surprised by the clothes he and his brother wore in the family photos.

"I can't remember how we got those outfits at all. We were very poor at the time. We were just coming out of the Depression. They look so expensive. My mother was also a seamstress. I think she made a lot of those clothes."

His father, Mr. Munhall said, "was just a perfectionist. He got these books and learned what to do and bought the equipment."

On the weekends, the Munhall family's dining room and kitchen became a dark room, although red bulbs were installed overhead to give enough ambient light. Young Edgar's job was to lay out the pans of chemicals.

"I was just fascinated to watch these images slowly come out of the chemicals. The smells were unbelievable. As a child, I thought they were awful."

Mr. Munhall loves the spontaneity his father captured.

"I thought both Breed and Spencer were obviously of a higher social caste and there's a kind of stiffness and primness about the pictures which Walter's doesn't have. Their clothes are perfect. They stand more formally. I don't think Walter had any idea of being a pictorialist, whereas Breed and Spencer did."