Archived posting to the Leica Users Group, 2000/11/10

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Subject: Re: [Leica] Re: DOF...OK...Think I've got it.
From: "Jason Hall" <JASON@jbhall.freeserve.co.uk>
Date: Fri, 10 Nov 2000 23:19:18 -0000
References: <5.0.0.25.0.20001109122440.00aab280@206.34.200.40> <5.0.0.25.0.20001110141321.00aafc30@206.34.200.40>

> How would Printing to the same (or different) size effect DOF at
all? The
> focus of the negative in the enlarger is a flat plane, and has no
depth to
> manipulate. Anyone know of a better forum for this discussion?



The focus on the subject is also in a flat (for the sake of this
argument) plane, everything in front or behind is out of focus to a
greater or lesser extent, apparent depth of field is simply a
consequence of the degree of magnification of the out of focus areas.

Increase the magnification (long lens or bigger enlargement) reduce
the apparent depth of field

Reduce the magnification (wideangle or smaller enlargement) increase
the apparent depth of field.

Cropping and enlarging has the same effect as using a longer lens,
increasing the COC thereby reducing apparent depth of field.

AA Doesnt explain this clearly (in fact his explanatoin as quoted by
Michael is over simplistic and misleading IMO), you have to dig around
to understand it and I think this forum is perfect for batting this
around until we all have it clear in our minds.  Now I have to try to
grasp the perspective thing!

Jason Hall

In reply to: Message from "M.E.Berube" <MEB@goodphotos.com> (Re: [Leica] Re: DOF)
Message from "M.E.Berube" <MEB@goodphotos.com> (Re: [Leica] Re: DOF...OK...Think I've got it.)