Archived posting to the Leica Users Group, 2001/02/08

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Subject: Re: [Leica] Re: DOF, thanks Austin
From: Johnny Deadman <>
Date: Thu, 08 Feb 2001 11:21:21 -0500

on 2/8/01 10:25 AM, Austin Franklin at wrote:

> Well, I believe the term is correct, and here's why.  DOF is a term used to
> describe the effect/result, not related to the cause.  If the cause is
> optical, or resolution, the result is the same.  If you want to qualify DOF
> with 'optical' or 'resolution threshold', that's fine by me.  I still
> believe it's both relate to the linear distance of the original
> scene that is considered 'in focus'.

No, with respect, you're not addressing my point, Austin. DOF as commonly
used (eg in published DOF tables, lens engravings and published formulae)
refers to DOF of an image at a particular nominal magnification and has for
fifty years. Your definition doesn't. Therefore I think it needs to be
distinguished in some way from the traditional definition or the mass
confusion we have seen here results. I can't see that your definition of DOF
can just be substituted for the traditional definition, whether or not it's
more accurate or logical.
- -- 
Johnny Deadman