Re: Image sharpness and focus distance.

[Les Newcomer <lnphoto@xxxxxxxx>]

This is true for still cameras but not rotational cameras since with a
rotational camera you are photographing the interior of a cylinder (the
focus point). The speed at which the film travels through the camera
(not to be confused with film speed!)must be matched to the focused point.

Assume a camera is focused and set up for a point 30 feet away.

Since the circumference of a cylinder 30 feet away is vastly larger than
a cylinder 20 feet away, the film will travel at the wrong rate for the
shorter distance and be seen as soft or blurred inspite of the fact that
this point fell within the limits of depth of field.

Les