I have a Canon Digital Rebel XTi and only have the kit lens right now. I am looking to upgrade for a trip I am about to take to Japan. I don't need any zoom lenses as my Father and Grandfather have many for me to borrow. How ever I want a lens of my own for walking around. I have read through many posts, and have become interested in the Sigma 17-70mm f/2.8-4.5 DC Macro lens. What do you guys think of it? Also I have seen a lot of talk about the Canon 50mm f 1.8 lens, should I look at getting this also. I am trying to keep my lens purchase under $400. After this trip my photos will mainly be of buildings (exterior and interior) as I am a Property Manager. With some landscapes that I take while hiking. Thanks for any help!