Well I finally think that I might have narrowed down the " walkabout " lens that I want. I want something that I can leave on my 40D most of the time. I have a nifty fifty, a Siggy 10-20, and a Tammy SP 90 macro. So nothing is really a walkabout. Would like to hear from anyone who has any expreience with the Tamron 28-75 f2.8 XR Di LD IF. ( what a mouth full ). Seems to tick all the boxes. Have read some good reviews. Will probably take the plunge this week.