« on: February 12, 2012, 03:52:25 PM »
If you're using phase detect AF and selecting a single AF point, the camera is not going to focus somewhere else in the scene, it will use only that AF point. (Side note - even Spot AF uses an area a little bigger than the AF point representation in the viewfinder; regular AF is even larger relative to the little box.) So, if Live View on a particular spot consistently results in correct focus, and the phase detect AF is giving you about 80% front-focused shots, then your phase detect AF system needs calibration, and that's what AF microadjustment is for.
I'm not sure what Phase Detect is, could you please describe things in more details?
What I do is:
1. Turning on my camera.
2. When looking through the viewfinder focusing at a subject by using central point (the big one or the small one, it doesn't matter).
3. Pressing the shutter release button half way to focus.
4. When I hear focus confirmation sound I press the button down.
5a. If the area that my focus point was pointed at has high contrast I have a crisp shot.
5b. If the area was not contrast enough (see my first two samples at the first message), I get front-focus.
P.S. I'm always using one focusing point for One Shot. AI Servo is normally used by me for birds and other fast moving creatures, but I didn't check its accuracy, so can't say if there's an issue with AI Servo too.