My understanding is that essentially all lenses are flat field. Many start
to deviate from flat field as they are focused close. I also remember claims
that the close up diopter lenses also usually gave a non-flat field with
close focusing.
The macro lenses are optimized for focus at other than infinity. I think
many actually optimize for a 1:10 size ratio even though they focus much
closer.
-jeff
----Original Message Follows----
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxx>
I think the true definition of a macro lens is that it is well corrected
for image magnification of 1:1. They also have flat fields for copy
work and likely negligable distortion as well. Nikon's lenses may all
have flat fields but I'll bet their high priced macros have even flatter
fields :-) How flat is flat?
If you were photographing a painting I think you were far enough away
that any good quality prime at apertures of f/5.6-11 would hide any
optical sins.
Chuck Norcutt
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