I have owned the Canon Digital XT for two months now. I am new to the Digital SLRs. It came with the EF 18-55mm and I just purchased the Canon 28-135mm F3.5-5.6 IS. I would like recommendations for lenses that can take me from sports to portraits to scenery to anything. I want to buy as few as possible but have a variety of possiblities. I can exchange the 28-135mm if I need something with a different range.