When I think about the thousands of tree photos I've taken over the years, I'm reminded of the Art student I saw at UW one Quarter back in the 70s. She was sitting at the Drumheller Fountain on campus every single day I passed by, working on some pastel? or colored pencil drawings. The water, the lighting, etc...it's different every day, every hour depending on the weather. It's the same with my "tree" photos, and I find subtle differences even when I shoot several shots of the same image. Since I like to shoot with the "Auto" setting, I'll aim at different focal points to see what changes happen from shot to shot. I do the same kind of thing when I'm editing. "What will those greens look like when I convert the image to black and white?" "What if I go further and sort of zoom in on the lines and shapes and values...?"