Steve, Many thanks for the compliments. I purchased my 800mm f5.6 way back in 1990. Hard to think its 22 years old now. Great lens, but,very difficult to use if the conditions aren't correct. For example, I was at Suzuka,Japan in 1990 for the 8 Hour Motor Cycle Race.
The lens didnt work that well there,as,in some conditions, the heat coming up from the ground,made many of the images "soft". 38C heat, and 90% humidity is tough work. Thats 100 degrees F in the old scale.