Archived posting to the Leica Users Group, 2001/02/11

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Subject: Re: [Leica] DOF: Erwin
From: "Jacques Bilinski" <jbilin@axionet.com>
Date: Sun, 11 Feb 2001 07:35:49 -0800
References: <B6A9CF7B.E2A2%jbcollier@home.com> <00dc01c09380$c21002a0$0201a8c0@marklaptop> <3A859BD6.B61C94D9@rabiner.cncoffice.com>

> Erwin has a nice page on DOF issues:
> http://www.imx.nl/photosite/technical/DoF/DoF.html
>
> I quote out of context to pique your interest:
>
Erwin states:
>>>>>
 So the calculated depth of field is eqaul on both sides. The welllknown
rule that the total length of permissible sharpness extends 1/3 in front and
2/3 beyond the image plane/plane of focus is derived from the fact that many
enlarged pictures are not viewed from the proper distance that is required
when the perspective of the lens and at the moment of the picture is the
same as that from the viewing distance. Many pictures are viewed from a
distance that is too short for the proper perspective.
<<<<<<
So you are looking at this photograph. The depth of field is 1/3 in 2/3 out.
You now move the photograph away from your face to its proper viewing
distance for perspective. The depth of field is now 1/2 in 1/2 out. This
seems highly counter intuitive to me.

Replies: Reply from Shan <shan@montana.net> (Re: [Leica] DOF: Erwin)
Reply from "Tim Spragens" <info@borderless-photos.com> (Re: [Leica] DOF: Erwin)
In reply to: Message from John Collier <jbcollier@home.com> (Re: [Leica] DOF: Depth of Field article online)
Message from "Mark_E_Davison" <Mark_E_Davison@email.msn.com> (Re: [Leica] DOF: Depth of Field article online)
Message from Mark Rabiner <mark@rabiner.cncoffice.com> ([Leica] DOF: Erwin)