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From: porter@inuxd.UUCP (J Porter)
Newsgroups: net.rec.photo
Subject: Re: Slide Projectors (more)
Message-ID: <398@inuxd.UUCP>
Date: Mon, 12-Dec-83 19:13:29 EST
Article-I.D.: inuxd.398
Posted: Mon Dec 12 19:13:29 1983
Date-Received: Wed, 14-Dec-83 01:18:01 EST
References: <1825@ihnss.UUCP>
Organization: AT&T Consumer Products Div., Indianapolis
Lines: 44

Since everyone seems to be knocking Kodak Lenses, let
me give you the straight poop on them.  I sent mail to
the original requestor, but for the rest of you here goes.

A few years ago, I used to work for Kodak (KAD Hawkeye Works
for those of you in the know), and I revamped the machine
that tests all of Kodak's Carosel Lenses.  The bad PR on
Kodak's lenses is coming from "Curve field zoom lens owners".
Compared to their other lenses, this one really sucks;
however, this is the big runner.  If you want a good lens,
get a fixed focal length lens - they make two sizes.
The MTF (Modulation Transfer Function) of the fixed focal
length lenses is great!  (ie:  the ability of the lens
to resolve things in the corners (radially and tangentially)
is the same as in the center, and the corners are in focus
at the same time the center is.)  The zoom lens however,
has problem in getting the edges in focus, at the same time
the center is.  It is a much more complicated lens to design
and manufacture.  The same is true for zooms on your SLR.
You are going to get a better picture from a fixed focal
length lens.

Now what about this "curved field stuff"?  Well, everyone
knows that slide will "buckel" from the heat of the light.
Kodak had statistically studied the buckeling of slides
and has compensated for this in their lens design.  (ie:
the film is curved, so lens was designed for a curved
focal plane, so that the edges and center would be in
focus at the same time.)  For all you hard core slide
enthusiasts that don't believe in buckeling film,
Kodak still makes the old reliable flat field lenses,
just like everyone else.  Again the zoom model is not
as good as the fixed focal length lenses.

I can bet that most people show their slides in the very
same location everytime, and really don't need the zoom feature.
Unless you regularily have to adapt to different
projector to screen distances, don't get the zoom.
Stick with a fixed focal length, curved field lens,
you'll be amazed at the difference.

Jeff Porter  (inuxd!porter)
AT&T Consumer Products
Indianapolis