I picked up this lens used on ebay. When I received the lens I was nervous at first as there were some difficulties using the lens with my digital bodies. My Nikon N90s was fine, but the digital cameras were having focusing issues. A call to Tamron later and I found out the lens had an out-dated cpu-chip in the lens; shipped lens to Tamron in NY and two months later I got the lens back. Works better now.
Okay so how about that lens? I like the lens, the cost of the lens was a major factor in its purchase. I would have liked to purchase the Nikon Telephoto AF-S f/2.8G ED-IF VR lens at this time, but alas no funds do I have for such a purchase. At the time of my writting this review I had the Tamron lens in my possesion for almost a month (since being repaired). The weight I do not notice, as the lens is attached to a monopod when I use it. The switching between manual-focus and auto-focus I like since there is no button to accidently switch, you must instead rotate a cover out of position in order to mess with the fine-focus adjustment wheel. The auto-focus feels slow, this is a subjective statment at this time since I have not rented the lens available from Nikon to do a side-by-side. Depending on which camera body I use, determines the amount of extra searching for the auto-focus.
I think that actions speak louder than words so here are some images that I have taken with the lens. <a href="http://www.mystphoto.com/reviews/tamron/af300mm">http://www.mystphoto.com/reviews/tamron/af300mm</a>