Archived posting to the Leica Users Group, 2004/02/17

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Subject: Re: [Leica] Oh god please no! Not DOF again
From: John Collier <jbcollier@shaw.ca>
Date: Tue, 17 Feb 2004 06:23:57 -0700
References: <47A5E9D4-60DD-11D8-AAF0-0050E42E6E0B@shaw.ca> <005801c3f508$c6f38f20$6501a8c0@jbilinsk> <10DE00DE-6101-11D8-9109-0050E42E6E0B@shaw.ca> <002c01c3f51d$cbfcb9a0$6501a8c0@jbilinsk>

Sorry mate, this is the same person with the same reasoning. DOF varies 
because he is allowing objects equidistant from the plane of focus but 
at different magnifications to be directly compared. Once the 
magnification is equal, the DOF difference disappears -- which he also 
demonstrates BTW. His statements are not wrong, you are just incorrect 
in thinking they refute my mine.

John Collier

On Feb 16, 2004, at 11:18 PM, Jacques Bilinski & Barbara Bradbury wrote:

> Here's another site which addresses this subject:
> http://www.vanwalree.com/optics/misconceptions.html
> It states "In particular when the object distance is not small 
> compared with
> the hyperfocal distance, a short-focus lens will irrefutably offer 
> more DOF
> than a long-focus lens - at the same F-number and image 
> magnification." So
> according to this a shorter focal length can offer more DOF at the same
> magnification.

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Replies: Reply from "Jacques Bilinski & Barbara Bradbury" <jbilin@axionet.com> (Re: [Leica] Oh god please no! Not DOF again)
Reply from Ted Grant <tedgrant@shaw.ca> (Re: [Leica] Oh god please no! Not DOF again)
In reply to: Message from John Collier <jbcollier@shaw.ca> ([Leica] Oh god please no! Not DOF again)
Message from "Jacques Bilinski & Barbara Bradbury" <jbilin@axionet.com> (Re: [Leica] Oh god please no! Not DOF again)
Message from John Collier <jbcollier@shaw.ca> (Re: [Leica] Oh god please no! Not DOF again)
Message from "Jacques Bilinski & Barbara Bradbury" <jbilin@axionet.com> (Re: [Leica] Oh god please no! Not DOF again)