Nikon D4 - Manual (Page 47)

43
Autofocus Tips
Checking Focus Checking Focus
Position a ruler at an angle so that one of the rules is at the
same distance from the camera as a vertical surface such as
the cover of a book stood upright. Using autofocus, focus
on the vertical surface and then photograph the selected
rule using focus lock.
The illustration below shows how to interpret the results.
Camera focuses in
front of selected
rule: adjust fi ne-
tuning upward.
Camera focuses
on selected rule:
no adjustment
required.
Camera focuses
behind selected
rule: adjust fi ne-
tuning downward.