Great forum and good advice. Here's my first posting.
I have now owned my 400D for a few months and am ready to upgrade my lenses. As well as the kit lens, I currently have an old (but really useful) canon 35-135usm and tokina 20-35. The main deficiences of these lenses are lack of sharpness and nothing to show at the telephoto end.
My key uses will be informal photos and portrait shots of the kids (mainly outdoor) and occasional sports/action photography. I would like to stick with Canon but would be prepared to go independent if this will deliver sharp photos and quick focusing at a reasonable price. I'm not too worried about the wider end (the kit lens will be OK for this) and so would be happy to go with a range of 24/28mm upwards.
The mid range zooms I've so far looked at on paper are 17-85 IS USM (which seems to get mixed views on sharpness - including on this forum), 24-105 L IS USM (pricey but apparently a cut above the rest) and 28-135 IS USM (which would be closest to my current 35-135 - but is the image quality markedly better?).
The telephoto zooms I'm considering (or can afford to consider!) are the 70-300 IS USM (seems to have good reviews for image quality but questionable build quality) and 70-200 L USM (a step up but fairly bulky to carry about and not very subtle!).
Any advice and views on these lenses (or any independent equivalents) would be much appreciated. I want to get the best image quality I can for the best price (like most people I guess!).