A quick 'Howdy!'

Just a quick 'hello' from a new guy to the forums. After 5 years of digiscoping with a Coolpix 4500/Zeiss 85T combo, I just got a new 350D/18-55mm kit from the wife as a "job well done" gift for a woodworking project I finished for her. It's already been blessed with the BG-ED3 and an EF 100mm f/2.8 Macro USM, and I'm leaning towards purchasing the EF 100-400mm f/4.5-5.6 L IS USM for wildlife/birding. Naturally, a "nifty fifty" has to be in the kit for those grab-the- camera-and-go times.

I need some opinions here: For an excellent wide-angle lens, should I go with the Sigma 10-20mm f/4-5.6 EX DC HSM, or stay with Canon and the EF-S 10-22mm f/3.5-4.5 USM?

Welcome to POTN

Oh boy this is going to cause an argument

They are both fairly even, the Canon has better flare resistance and slightly better colours but as many will say the Sigma is cheaper, equally as sharpe, comes with hood and pouch and the colours can be corrected in post processing. So it comes down to how much you want to spend, as far as i know the Canon has rebates avaiable at the moment...

Welcome to POTS as well.  Well, no argument from me. Canon all the way. IQ = same, range = same, color = Canon, cost = Sigma so all looks even until you toss in servicing or problem resolution. If you ever get a ERR99 issue or focus seems off or any number of other issues that can arise, with a Canon body and lens you have one place to do to for resolution, Canon. With a mixed setup you have two big companies pointing at each other claiming the fault is with the other.

The Sigma is a better value for your money - as Sigmas tend to be in a lot of focal ranges to be honest.

I would not rule out the Sigma offering simply due to some mystical (and highly unlikely) ERR99 issue that happens rarely at best.