I've recently brought the Canon 350D with 18-55mm & 70-300mm lens as a starter kit. I am very eager to use the camera to its full potential and get in to it more professionally. I continue to come up against the term: 'f/11..'. or 'f/8...' Probably a really obvious question but what does the 'f' stand for in these terms? and what function does it perform? ( Im one of these people who really likes to understand everything properly before feeling confident to progress!!) I would be very grateful for any 'idiot guide answers' for complete beginners or any relevant books/sites i could visit which can explain all the main basics to someone like me. Many Thanks.