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Re: [OM] More on DOF and focal length (by Ctein)

Subject: Re: [OM] More on DOF and focal length (by Ctein)
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Mon, 29 Jun 2009 07:45:26 -0400
No, that's what you are saying.  It's not what Ctein is saying.  Ctein 
is saying the depth of field will be different if you *move* the camera 
to maintain the same magnification after *changing lenses*.  His 
argument has nothing to do with post-processing the image magnification 
on shots taken with different focal lengths from the same distance.

The whole point of the article is that, after moving the camera to 
maintain the same magnification, the shorter lens will have greater 
total depth of field and proportionately more behind the subject rather 
than in front.  Any good depth of field calculator will show that to be 
true.  Changing image magnification in post processing without moving 
the camera is something that you and Jan have introduced.  It's not part 
of his argument at all since he doesn't even address it.

Chuck Norcutt


Ken Norton wrote:
>> You mean the DOF will be the same for a 25 and 300mm lens at same shooting
>> position, aperture and subject distance? It is hard to believe.
>>
> 
> Yes, if you crop the image from the 25mm lens to the exact same framing as
> the 300mm image and then print or display them at the same size.
> 
> That's my argument and Ctein seems to be saying otherwise.
> 
> AG
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