I've just purchased a Canon T1i (500D) to replace my aging Panasonic/Lumix camera. It came with the 18-55 kit lens and I want to upgrade to some better quality glass. My shooting is hobby... landscapes, architecture, people, dogs, cars, flowers, whatever strikes my fancy, etc. I'm looking at these options that cover the range I need (from cheapest to most expensive): 1. Canon EF-S 17-85 f/4-5.6 IS USM ($300 on CL) 2. Canon EF-S 18-135 f/3.5-5.6 IS ($450 on CL) 3. Tamron AF17-50mm/2.8 XR VC ($650 new) 4. Canon EF-S 15-85 f/3.5-5.6 IS USM ($800 on CL) 5. Canon EF-S 17-55mm f/2.8 IS USM ($950 on CL) Questions: Which of these is the best value? Is #5 worth 3x #1? What's the optical trade-offs involved in #1-#4? For example, I've read the Tamron is soft at f2.8 which brings the whole value of that lens into question. Should I put much weight in USM (re: #2)? I assume I should be more concerned about optical quality. Is there an obvious choice I'm overlooking? If it was your hard-earned money looking for a good hobby walk-around lens, what choice would you make?