I'd like to get a nice Telephoto lens for my D90. I had a photographer friend mention that Tamron makes nice Telephoto lenses so I priced a Tamron and a Nikon. Only about $100 difference in price, but the Tamron goes to f/4 and the Nikon only goes to f/4.5. Here's the link for the TAMRON I am considering: http://www.amazon.com/Tamron-70-300...9DZE/ref=sr_1_6?ie=UTF8&qid=1291044352&sr=8-6 And a link for the NIKON: http://www.amazon.com/Nikon-70-300m...PK2C/ref=sr_1_2?ie=UTF8&qid=1291044766&sr=8-2 Does anyone have any opinions on / experience with either of these lenses? Thanks in advance!