300rd - how good is the AF in real world on 5D II?

joger wrote:

But the really reason for that is surely point 1. I am planning to photograph race cars later this year with the new lens. Will probably post the results here. But if you are interested in fast action you might want to have a look at my greyhound images - those dogs are really really fast! It is much more critical to get a high frame rate here - that was the first time i recognized that everything below 8 or 10 fps is too slow. The keeper rate was significantly lower - most images have not the right composition. Too many feet on the ground and/or framing wrong and of course focus slightly off - but also here quite amazing results - I guess it is also getting used to that kind of action - something completely new to me. (many photograpphres with expensive gear at those events)

You can photograph road race cars with 3 frames per second. More is better, but 3 is enough. And you can look at it this way. You'll have far fewer frames to toss out if you are maxed out at 3 fps and have a little buffer like you have in the 5DMkII.

Something to think about: Cars are large. Depending on how far it is to the track surface and race line from where you are standing with a 300mm lens, they can go from being perfectly framed to being chopped off at both ends in an instant. I'd say they are fast. I think you'll find it completely new if you haven't already done it.

Pretty colors

Be careful of shooting at fast shutter speeds. The car above at 1/4000th would look like it was parked.