Archived posting to the Leica Users Group, 1998/12/07

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Subject: Re: [Leica] Wrist Straps, DOF, subject line
From: "Henning J. Wulff" <henningw@archiphoto.com>
Date: Mon, 7 Dec 1998 20:30:33 -0800

Jim Brick wrote:

>By the way, DOF extends farther behind the point of focus than in front.
>The rule of thumb is 1/3 forward, 2/3 back, from the exact point of focus.
>This is not an exact ratio, but when photographing it's very very close.
>Consult the scales on your lens to see this.

This applies only at certain distances. Obviously, if you focus at the
hyperfocal distance (hyperfocal being determined by whatever DOF criteria
you set) or further, DOF extends an infinite amount behind the subject, but
a finite distance in front.

If you are shooting at 1:1, DOF extends exactly as far behind as in front.

That leaves a whole lot of other distances, which we normally shoot at, so
called middle distances, at which the 1/3, 2/3 rule gives an approximation.


   *            Henning J. Wulff
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