Re: [Leica] Re: DOF

[Douglas Herr <telyt560@cswebmail.com>]

On Thu, 09 November 2000, "clive sanbrook" wrote:

> 
> sorry - but that doesn't sound right- surely once a image has been captured
> on a negative with a certain amount sharp - and some not so sharp - I can't
> see that  cropping it via an enlarger can possibly make any difference to
> the parts of the negative that are sharp or unsharp? Are you thinking of
> perspective? I understand that if an image taken with one focal length lens
> is enlarged to the same size as an image taken with a longer lens then the
> prespective will appear the same i.e the various planes of the photograph
> appear to change their relative spacing?
> 
> Any comments?
> 
> regards
> 
> Clive Sanbrook
> ----- Original Message -----
> From: "Brougham" <brougham3@yahoo.com>
> To: <leica-users@mejac.palo-alto.ca.us>
> Sent: 09 November 2000 14:25
> Subject: [Leica] Re: DOF
> 
> 
> > "M.E.Berube" <MEB@goodphotos.com> wrote:
> >
> > > I think we are saying the same thing Doug.  Wide Angle focal length
> > > lenses give us greater depth of field than their more tele
> > > counterparts at like apertures. Regardless WHY they have greater DOF
> > > (reduced image magnification that is inherent in shorter than normal
> > > (wide angle) lenses or magic)..Wider focal length = greater DOF.
> >
> > Yes.  And no.  :)
> >
> > If you crop a picture shot with a wide angle lens and then enlarge it
> > so it is comparable to a print made through a longer lens, the DOF
> > will be the same in both prints.  The actual lens doesn't affect DOF.
> >
> >

Clive,

When you enlarge the photo you also enlarge the circle of confusion and what may have been acceptably sharp at the boundaries of the depth of field will become unsharp when enlarged.

Doug Herr
Birdman of Sacramento
http://ourworld.compuserve.com/homepages/telyt
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