I bought my gf a GF1 some months ago, and am ready to purchase a standard zoom lens for her. The only lens she currently owns is the 20mm f/1.7 pancake. That being said, what is a good zoom lens that gives a sharp picture, and does well under low light conditions? My budget is around ~$600 max. Ideally, I want to use a zoom lens for everyday use, such as portrait, landscape, and street shots. I looked into the Panasonic 14-45mm lens, but now seeing if there are better alternatives. I found 100-300m to be a bit 'overkill' for my needs. Any recommendations? One other quick question. What is ideal for shooting in 50mm? Does that give a pretty zoomed in view? Also, is there a good website/resource where one can buy used lenses? Thanks.