Oh, I'm a huge Dorothea Lange fan too! In fact, I was just taking pictures this weekend trying to put a little of her style into mine. I love photographers that powerfully capture emotion.
I love Ansel Adams too. Man, what I'd give to be able to consistently do landscapes like him.
Wow, that's hard. There is so much talent, and so many images that really speak to me.
Off the top of my head, for the pre-digital era I would go with Ansel Adams. His use of light, texture, and focus, are simply amazing. Most of his work would be so much less, if it were in color. I am as much in awe today, as when I first saw his images as a kid.
For current digital photographers, I'd tap our own JoeyL. Again a person with amazing vision. I look at his work in "Holy Men", and come away almost speechless. The light, the color, the texture of his images are fantastic. I come away feeling like I have some sense of the person on the other side of the lens. I would encourage everyone to read his blog that goes along with his visit to India. He can write about as well as he can shoot. I so look forward to what he will accomplish in his career.
