Last time this was asked I said:
I was in the country recently and was told a steam locomotive was due in about 20 minutes. I got to the location recommended , set up my 20D with 200mm lens on a tripod , and had my 5D around my neck with the 17-40.
Got a few shots with the 20D, then got some shots as it passed close by with the 5D.
HUGE ADVANTAGE.
, but I would keep my 10D for if I had a problem with my new one


