range in working distance for which the image is (acceptably) focused.
DOF = Far Point – Near Point
see also Bokeh
range in working distance for which the image is (acceptably) focused.
DOF = Far Point – Near Point
see also Bokeh
Most distant point on the optical axis with an image of “acceptable sharpness”
Where CoC is the Circle of Confusion (the largest accepted Airy-disk) in Millimeter.
Alternatively, we can express the FarPoint using the magnification M :
closest point on optical axis with an image that has „acceptable sharpness“
Where CoC is the Circle of Confusion (the largest accepted Airy-disk) in Millimeter.
Alternatively, we can express the NearPoint using the magnification M :
Yet another way to express the Near-Point is to use the Hyperfocal distance H :
If the lens is then focused to some object distance OD, this OD can be expressed as fraction of H :
or
Then the near point is
,
the far point is
and the Depth of field is
For we get
So, with
and
we get
For we get
So, with
and
we get
Therefore by decreasing the OD by factor 2, the DOF decreased by factor 4.
or, equivalent :