----- Original Message -----
From: "Vic Mortelmans"
Subject: Re: Wide lenses and close distances
A thought that puzzled me lately may be related to this question.
It's about the focal plane and the effective distance to the camera lens.
When you focus a lens to 1m, it means that all subjects are in focus that
are in a plane positioned at 1m from the lens and perpendicular to the
lens axis (the focal plane).
My understanding is that if the lens is a flat field lens (macro lenses tend
to such lenses), then this is the case, however, if the lens is a curved
field lens, then the plane of focus is actually dish shaped, with the
curvature keeping things in focus at the focus distance in a curved field in
front of the lens.
William Robb
