What do the focus points mean, like "C-C" and "U3-R2"?

Why  we use the Center Focus Point?

We test and adjust the AFA value using the Center Focus Point. This is because:

  • It is the most sensitive
  • It is not feasible to test all the focus points
  • Most camera only allow the setting of one AFA value per lens, anyway (except for short and long end of zoom lenses on some cameras).

In the FocusTune File Grid List we show the focus point selected in the camera in the Focus Point Column as shown here:

Why  we use the Center Focus Point?

How we display the camera's focus point used

Since each camera has a different layout for it's focus points (and a different quantity) we have come up with a system that allows the display of the selected focus point so that it can apply to any camera regardless of its AF focus point system quality and layout. It uses a system of 2 "designators", the first telling the row of the focus point selected, and the second telling the column of the focus point selected.

it is based on a generic grid of focus points using the center focus point as the reference, since all camera have a center point focus pointy. We will show 2 different focus systems to demonstrate our point (no pun intended).


  • C=Center
  • L=Left
  • R=Right
  • U=Up
  • D=down


How we display the camera's focus point used
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