About Perfect Focus Range
The Perfect Focus Range is a region in which everything looks clear in the camera view.
You can set the width of the Perfect Focus Range in terms of distance (centimeter):
This value actually defines the far and near boundary distances offsetting from the focus center (defined by the Focus Distance). Therefore, the value times 2 is the real width of the range. In the illustration below, the N is the value we see on the Perfect Focus Range field.
Through the camera with DOF on, the diagram looks like the illustration below:
Note:
The unit of the value for Perfect Focus Range is centimeter.