I'm an amateur shutterbug getting quite a bit more serious about this hobby of photography. Well ... I'm also confused by what a sales rep told me when I wanted to purchase the Canon 70-200 f2.8 IS lens online. Namely that on a 20D camera the lens would act like a f4.5 and have cropped fields do to the 1.6 factor of the camera. He wanted to put me into a "new" Sigma 70-200 f2.8 that would remain a f2.8 with no cropping on the 20D. He said the lens was different fom the Sigma 70-200 lenses offered by many other sources for less than $900.00. His list price for the recommended Sigma lens was $1999.00 ... but, of course he had a sale price today for $1550 ... including a UV filter and a polaroid filter.
Please set me straight. I want the best final result. Thanks for your input!