Bluesman; sorry for the tardiness of this answer, but I just got back home. So first off, I hope you had a good time and got a lot of good shots at the race.


Secondly, like Bob, I've owned the 100-400 for a few years now and I agree w/Bob, except w/keeping the shutter speed up for car racing.


I've shot a few auto racing events and discovered after my first event I parked the cars, i.e. the shutter speed I used (too fast) stopped the rotation of the wheels making the car look static. I now use shutter speeds (roughly) between 1/60 and 1/125 w/f stops 10 and higher. I've had good luck w/great weather....I haven't had to shoot a race in low light conditions which aren't the best conditions for the 100-400.


Example; Lime Rock CT, 40D, 1/60th, f14, panning handheld.


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I know this info is late, but hopefully it will help in the future or maybe you know this already...the 100-400 is a great lens for this type of venue.


Post some shots Bluesman.


Regards


Bill