hello all, i was wondering if anyone could help me out with a couple questions i have. what do you all believe is the best middle range lens for a d80. i mean like a Sigma APO 70-300mm F4-5.6 DG MACRO...... a mid-range (like 70-300 or something like that) a good aperture range... around 4 or lower that would cost around $300-450 and what lens is there that is in this price range and has the lowest possible aperture??? kind of confusing... but thankyou for your help!!