The Use of Photography as an Aid to Painting.
And then what do we use for painting? Do we slavishly copy a photo? Look at it for ideas? Only copy the things that'll take us ages to work out? Paint from memory? Paint from imagination. Sit out there and paint what we see? Or of course paint an abstract work, which may have been abstracted from a photograph anyway.
You have to take a photo with a pinch of salt. Shadows are too dark, colours are not the same as real life. I once took a picture of a bright red poppy in a mixed border. When I saw the photo it looked faded pink. That was not my memory.
There's a good article in November's Artists and Illustrators magazine about the use of photography, and also a very technical one about how to photograph your own work.