Freud,
I used 300 mm and 600 mm out of the hand - manuel focus - when I got my old analog stuff.
the 300 was a 2.8 steel body......the 600 a mirror.
I liked the 300 - have to wait to get a 300 for my digital equipment.......but the prize is only for proffesional affordable.....6500 dollars.....but to use them are a dream - just 4 pounds for the 300 2.8.....
The only trouble with the today auto focus lens are - that the manuel focus ring turns too easy - for high speed picture on the long distance you need them "stiff".