i'm not sure what the 1:4 is supposed to be as i've seen some lenses with that. Here are 3 lenses that i'm considering, i have the canon 20D.
doing superbike races.
Canon Lens EF 300mm 1:4 L Is
CANON EF 28-300mm 3.5-5.6L IS USM
Canon EF 300mm F4.0L IS USM
the 2.8 is out of my price range, and i'm not sure that one stop will make that much difference..or i could be wrong. lol
I just used the 70-200mm 2.8 L IS and its great but too short.




