På 14. jul. 2005 kl. 03.56 skrev William Robb:
----- Original Message ----- From: "Shel Belinkoff"
Subject: Theory of Equivalency
An 18mm lens on a Pentax DSLR should yield, within a very small
degree, the
identical result as a 28mm on a 35mm film camera. Two pics taken of
the
same subject from precisely the same location should be virtually
indistinguishable wrt image size and FOV Is this correct? What, if
anything, should be different between the two pics? I ask this
because
something tells me that they will not be the same in some respects.
Depth of field will differ, with the smaller format generating more
DOF at any given aperture.
Not sure by how much exactly, I expect you will probably open up a
full stop to get similar DOF from APS C sized digital as compared to
35mm.
William Robb
One step is the usual rule. Which means that I need an 18mm 1.4 to get
an equivalent to my 28 2.0...
DagT
http://dag.foto.no
