So My new tammie 17-50 came and as this will go on my 20d is my first experience with the dslr world. With the little metter from -2 to 2 on the little top lcd, should that bar always be in the middle for a correct exposure? In low light, my lens sometimes can take from 1-2 seconds to focus and sometimes just "hunts" and never focuses at all. Is this normal? IS there something wrong with the lens? Also, any tips on shooting landscapes and buildings? Artistic touches? Ways to hold the camera steady? P.s.-Other than noise, shutter speed blurr, etc, is there a difference in what combo of iso, aperture, and shutter that you use as long as you get the correct exposure? p.s.s-What aperture do you recommend for landcapes, streets, buildings, etc? Thanks for the help and Ill post em when I get back!