Focus Problems

[SeagullSteve]

I've been shooting a fair bit of sport - football, rugby etc and I have a lot of shots where the focus isn't on the players, but rather the background. Today I covered my clubs tournament and have had a fair few that need to be binned because the focus isn't on the players. I'm back for day 2 tomorrow and would like to get a higher percentage of shots that I can keep.

I'm using a Canon 550D with a Canon 100-400L lens. Focus is multi spot and either Servo or AI focus.

Even when a lot of the image is players the background still manages to get the focus in a fair number of shots. Any ideas what I'm doing wrong?

 

[DaiTheDragon]

You need to use center spot focus.

Dai

 

[Rovers_Andy]

Steve, use centre spot with surrounding assist points, also try back button focus, this makes a big difference (IMHO)

 

[SeagullSteve]

Steve, use centre spot with surrounding assist points, also try back button focus, this makes a big difference (IMHO)

Obviously I'm going to have to RTFM. I know how to set centre spot focus, but not how to set the other to be assists. It seems that they are all off when I select centre spot. And as for back focus button not even sure what back focus is (other than when there is a problem with a lens back focusing).

Thanks for the pointers - I'll certainly use centre spot today and see if that helps.

 

[TrevorP]

If the background is in focus, then the active point is either not on the subject all the time or there is insufficient contrast in the subject. If you are using an outer point it'll be less sensitive than the centre point. Multi point AF must start with the subject under the centre point.

Use AI servo focus. If using Centre point only, then you HAVE to keep the centre point on the subject which must have some contrast. Don't think the 550D has AF assist points like the 5DII. If using all AF points, then you have to start with the Centre point on the subject and continuous half press. The camera will pass AF to outer points if it detects the subject has moved to one of these points. Back button AF is when you set a custom function to enable focussing with a button under the right thumb. Can be useful to temporarily disable AF if something gets between camera and subject. Some skill is necessary to do this.