Nathan Gardner , Jan 23, 2011; 10:25 a.m.
I believe when you use full auto, the AF system will use all 7 AF points. By doing this, you are allowing the camera to choose what to focus on from those 7 points. If the camera focuses on something other than what your main subject is, then your subject will be blurry. If only one AF point hits your subject, you're giving the camera a 1 in 7 chance of choosing the correct AF point. If it chooses one of the other 6 it results in an out of focus photo. I always choose one AF point myself and I make sure that point is on my main subject when I shoot. This doesn't give the camera a chance to pick an AF point and me hope it picks the right one. I don't think you can choose an AF point in auto mode however, so you may have to venture into the manual modes to gain that control. I think Av is a good place to start. You choose f/stop and ISO and the camera does the rest; its almost like auto, but you're telling the camera what settings you prefer, but in the end its still "point and shoot." There's no adjusting dials between every shot. P mode is even more thoughtless than Av, but I like to have a little control in what the image will look like by controlling depth of field with the aperture settings. Hope this helps.