Brian, it's possible that the photographer has "locked" the image (if you have it in digital form only) to protect his/her copyright - and .tiff files are impossible to work on, anyway, until you can figure out how to save them as .jpgs.
I understand some photographers do this so that, if you want copies, you have to ask him/her for them - but I might be mistaken, and the interpretation of the law may be different from country to country. I'll happily concede, if I've been misled.
Deb
