Your K-3 works a lot like the Nikon and it is not hard to lock/unlock the AF point selection. Assuming you got where you are by setting:
- Front dial: AF.C
- Rear dial: 25 point grid (pink) on rear LCD with starting AF point darker red (e.g. Expanded Area AF (M))
The default location for the starting AF point is set using the 4-way controller. If it is at other than center (the default), it is because someone set it to where it is. To get it back to center and lock it there:
- Enable (unlock) point selection by pressing (no need to hold) the Change AF Point button at lower right on the camera back (rectangle with four arrows and a center point). The AF grid display on the rear LCD will enlarge. If it gets smaller, press again. The larger size means the selection feature is enabled (unlocked)
- Press the OK button. This will return the starting AF point to center
- Press the Change AF Point button at lower right again to lock the starting point to center. The displayed grid on the rear LCD will be small again.
The above may also be done with the eye to the optical viewfinder. When the Change AF Point button at lower right is pressed an icon similar to the button label will display in the viewfinder. The selected AF point will also show when changed. If the icon is not visible, the point selection feature is locked.
The things to remember:
- The Change AF Point button enables/disables point selection. When it is off, the feature is locked.
- Whether point selection is enabled (unlocked) is remembered until it is disabled (locked). This is true even if the camera is turned off and on again. This is not good, IMHO, but I suppose some people like this behavior.
I hope this helps.
Steve