I need to learn to develop film for a photography class I am taking next year. I've been shooting digital with my 550d over the last year. I can use my Highschool's darkroom for developing film. I've watched videos on developing and I feel I have the gist of it. But one thing, I'm not too sure on how long I need to have the developer in contact with my 35mm Kodak Tmax pro 400 b+w. Any help would be greatly appreciated.