which lens is better, Canon 70-200 f/2.8 IS USM or Canon 100-400 f/4.5-5.6 IS USM?

Question

Its for sports photography

Answer 1

Here are several review pages and you can check these lenses out yourself, since YOU know what your priorities are.

You didn't say what kind of sports, but I'll guess that speed is important. You didn't say what kind of camera you have, but I'll guess that you have a digital camera.

If my guesses are both correct, I'd suggest the 70-200. The effective focal length would be 112-320. The 100-400 would become a 160-640, which is a KILLER lens for shotting close-up shots from the stands or sidelines, but that 160 might be just too tight a focal length for taking views of more than one or two players.

http://www.the-digital-picture.com/Canon-Lenses/ (See "Recommendations" on this page. They list both outdoor and indoor sports. The outdoor sports discusses exactly the two lenses you are considering. Naturally, it says to buy both.)
http://www.photo.net/canon/#lense
http://www.wlcastleman.com/equip/reviews/index.htm
http://www.photozone.de/active/news/index.jsp
http://www.bobatkins.com/photography/index.html
http://www.fredmiranda.com

Answer 2

They are both amazing lenses! The lower the F number the less light you need allowing you to use faster shutter speeds. The 400 mm is probably better for football matches when you are on the side lines and you want to get close to the action. Both lenses will be as sharp as each other...very high quality.

Answer 3

they are both very good lens for sports.
but which is better depends on what you want.
the 70-200 gives you a wider depth of field
and the ability to operate it under lower light conditions, while the 100-400 gives you a longer telephoto range.
so what do you want from your lens???
God bless,
gabe