Problems with autofocus, any suggestions?

[jermyzy]

Recently got back from a Tanzania safari.  Bought a t3i to replae my old P&S. I'll be honest, I didn't take the time to learn how to use it properly, so I left it on auto mode 90% of the time.  Anyways, when I got home and downloaded all the photos, I noticed that about 50% of the photos had problem with focusing on the wrong thing (e.g. If I try to take a picture of an animal, it would focus on the small tree branch in front of the animal, so the animal would be blurred).  I was using autofocus on a tamron 18-270 lens.  Any suggestions on how to correct this in the future, or do I need to use manual focus? (I tried this, but even then my pictures ended up out of focus).  Thanks!

[TCampbell]

By default the camera will use all 9 AF points, but you can tell it use a specific single point.

If the camera is in the default (all 9 AF points active) mode, then it can't focus on all subjects at different distances simultaneously -- it has to choose a subject.  The camera is programmed to always choose the subject which can be focused at the NEAREST focusing distance.

Much of the time, this would be exactly what the typical photographer wants.  But if you have anything nearer to the camera than your intended subject then it will tend to focus on that distracting element rather than your intended subject.

The fix is to use single AF-point mode as this puts you in control of focus.