Originally posted by RobG Thanks for the info. Do people actually select focus points for a flying aircraft or fast moving bird? I'm not being sarcastic; personally I find it easier to use centre spot focus and reframe or crop the image. Using the controls on the back of the camera also tends to be awkward when you are looking through the viewfinder with your left eye.
I like to select an AF point to better reflect the area I want to focus on for BIF, cars and bikes.
One of the reasons why I like to use this approach is if I am using the center point often times that puts the back half of the target closers to the outer frame of the photograph and give a chance of clipping the target.
Also when panning faster moving objects while using a slower shutter speed to show movement in the capture it is critical for you to hold a sight point over the same point of on the target for panning, I use the AF point for this. When the target is not moving perpendicular to camera we can get funny distortions that appear as OOF areas or shallow DOF even when we have more than ample DOF. What is happening is the perspective is slightly changing and this appears as blur as the movement from other places on the target are moving differently in the pan .
If you take a look at the photo below I placed my sight (AF point) over the people in the car and used that sight as an anchor to the target and tracked the movement of the car thru the exposure.
Using F13 I should have more than enough DOF but you can see that different parts of the car would need to be tracked differently if I want to stop the blur from the movement in the pan.
The closer you get to the target being perpendicular to the camera less of this distortion