Not actually about filters as nothing mnore to add other than to endorse the comment that you should stick a UV filter on every lens you own and leave it there.
Just wanted to check Maddy whether you are going for the right lens. You may well be for what you want and that is fine. Just that the 100mm f2.8 macro lens is one of the most popular lenses in Canon's range and I wouldn't want you to end up with the wrong one. The macro one is about £75 more but gives you one of the best macro lenses around, allowing you to get up nice and close for superb shots that are pin sharp.
The Non-macro version does have a slightly wider aperture at f2, just under one stop extra, but you'll get plenty of excellent blurring at f2.8 and the extra benefit of macro. The lens is slightly longer than the f2 version but that version only has a closest focusing distance of 3 feet whereas the macro version is one foot. When you consider that distance is from subject to sensor, it basically means you can get as close as about 5 inches from your subject. It is true macro, ie it gives genuine 1:1 lifesize reproduction, meaning the size of the object you are photographing takes up the same amount of size on the sensor. You can entirely fill the frame with a normal postage stamp!
Anyway, it may well be that you know all this and I am just blathering on and boring you to pieces so i'll shut up now. At least you know about both and can choose the one you want for your needs. Sorry if I was teaching you to suck eggs.
Cheers,
Rob
