AI Servo focus issue - Canon 7D

[pearson]

Hi, I am having an issue with my 7D when I am using my 70-200mm f2.8L II IS USM when shooting fast moving objects. I do quite a bit of motocross photography and have found since I purchased these two items my keeper rate has skyrocketed, but......if I am tracking a fast moving object as it comes towards me and adjusting the zoom while shooting in AI Servo mode I get the first 4-5 shots in focus but as I wind the zoom level down as the subject gets closer to make sure they're framed correctly I get a couple of shots that are well out of focus. The camera sems to buffer up most times this happens as well.

Is it because I'm asking the camera to do too much at once by altering the zoom while shooting in AI servo mode on continuous high?

Any info would be greatly appreciated

John

[ExclusiveAV]

I wonder if your CF card is fast enough?

[pearson]

I was reading another thread after I posted this about CF card speed. Perhaps that's the issue? I sure hope so! Best to spring for a faster card to see if there's any changes.

Thanks for replying

John

[etherial]

There are settings in the custom menus for focus tracking priority. Get you manual out and have a read, but from memory there are settings where you can set the priority to be either continuous shooting speed or focus priority (and the shot rate drops a touch). There are also settings for AI servo sensitivity as well. Might be an idea to experiment with those.

[KeeFy]

Look at the custom settings as etherial mentioned. Adjust to AF priority biased and not drive, also check that you have 2.5m focus limiter enabled. There are other bits of settings to muck around... you'll soon find one that suits you best... but not before loads of missed shots.

I used to take my dog (JRT) running towards me and stuff and using the same method.. too me a while to get the settings right.. but got there eventually.

Enjoy shooting!