Re: [Leica] .... flatness .....

[John Collier <jbcollier@home.com>]

on 18/1/00 7:55 am, claire at clairetm@singnet.com.sg wrote:
> 
> Can someone explain in simple terms what is "flatness of field' ?
> 

Here is a web site with a FAQ on lenses. There are many books available that
would give good basic descriptions of lens design. Why not give the local
library a try? Anyway here is the URL:

http://www.lib.ox.ac.uk/internet/news/faq/archive/rec-photo.lenses.faq.html

Here is a excerpt from that site:

* Curvature of field.  Points in a plane get focused sharply on a
curved surface, rather than a plane (the film).  Or equivalently, the
set of points in the object space that are brought to sharp focus on
the film plane form a curved surface rather than a plane.  With a
plane subject or a subject at infinite distance the net effect is that
when the center is in focus the edges are out of focus, and if the
edges are in focus the center is out of focus.

Sorry for being too lazy to write something in my own words.

John Collier