Shredder,
I am using my old Tamron 300 2.8 lens.
I bought that lens years ago for my Canon FTb.
When I got the Nikon D50 a few months ago, I bought the Nikon mount for the lens. Everything is manual on the lens and no metering with it. But with a digital camera, that is no problem.
Now, the new 300 2.8 prices will scare you. around $5,000.
Jack