Archived posting to the Leica Users Group, 2003/01/15

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Subject: RE: [Leica] To Austin, was RE: I eat crow
From: "Austin Franklin" <>
Date: Wed, 15 Jan 2003 10:20:25 -0500

Hi Herb,

> Austin,
> Perhaps putting Henning's statement in different words will help make
> it clear---
> The idealized theory in geometric optics is that a "perfect" lens
> transforms an object plane to an image plane.  Consider a plane out
> there in front of the camera, a plane that is parallel to the plane
> of the film.  If the image of any point on that plane is in focus,
> then for a "perfect" lens, the images of all points on that plane
> will be in focus.  Any deviation from this is the defect called
> curvature of field.  Now, it is obvious that points on the plane
> corresponding to the edge of the film are further from the camera
> than the point whose image is at the center.

Yes, I've been doing photography and designing imaging systems for quite
some time, such that this basic concept that Henning outlined is very clear
to me.  But, what Henning was outlining is a different issue than was stated
on Martin's web site (as I read it), as well as different than what I was
talking about.



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