László Moholy-Nagy. While he spent significant time with Adams, he let go of the obsessive desire for perfect sharpness that Ansel pursued relentlessly.
At some points in his career, Callahan seems to have done little photography with people as his subjects, usually restricting himself to his wife, Eleanor (above) and daughter, Barbara. He seemed quite fond of Eleanor's posterior end, and other private parts, as they found themselves into many of his pictures.
At others times, he made classic street images, quite close to his subjects, who apparently did not notice they were being photographed. In the 1950s, he did a series of very close images of faces, so close that the full face cannot be seen in the image.
Callahan was a true experimenter. The exhibit includes examples of multiple exposure, reflections, camera movement during exposure (including panning the camera while photographing static subjects). Late in his career, he did a significant amount of color photography, in the Southern USA, Hong Kong, and Europe.
I found the following quote by Callahan particularly interesting:
"As a chiild, my mother taught me religion in the moral sense, and early on I was motivated unconsciously by it. Later, I felt that I wanted to do something that would benefit humanity. I wanted something important, something spiritual in my life. And as these feelings developed, I found that my spiritual enrichment came through art. It was then that I realized I wanted to be an artist. That's it. You see, I learn slowly, but every day I seem to learn more."
I have never really looked at Callahan's work carefully before viewing this exhibit. I recommend it to anyone interested in the development of photography. If you will not have the opportunity to come to Washington, DC before March 12, you can view the photographs at this link from the National Gallery:
The list above is mainly that, a list. This link (also to the National Gallery) has a few more images: