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From: hyder@tekecs.UUCP (Paul Hyder)
Newsgroups: net.rec.photo
Subject: Re: film sharpness (Kodachrome)
Message-ID: <5476@tekecs.UUCP>
Date: Wed, 26-Jun-85 23:48:08 EDT
Article-I.D.: tekecs.5476
Posted: Wed Jun 26 23:48:08 1985
Date-Received: Fri, 28-Jun-85 01:31:30 EDT
References: <2807@decwrl.UUCP> <614@sfmag.UUCP>
Reply-To: hyder@tekecs.UUCP (Paul Hyder)
Organization: Tektronix, Wilsonville OR
Lines: 29

For the record the Kodachrome will always be sharper.

The primary difference between Kodachrome and Ektachrome is the 
method of dye production.  The dye is present in Ektachrome in 
colorless form and is converted to colored form in processing.
The dye molecules are large and sharpness suffers.  Speed increases
also can degrade the sharpness by requiring larger silver crystals
but the new technology is reducing this factor reapidly.  The other
problem is that the extra dye is not removed in processing of
Ektachrome, it just stays there in colorless form.  As Ektachrome
ages these residual couplers can become colored and cause color
shifts in the images, N.B. this is in addition to any "fade".

Kodachrome is a multi layer black and white emulsion with coupling
sites but no dye molecules.  The quality control is easier and
the sharpness improves.  Processing involves linking dyes
in the chemistry to the correct sites (Yep, three color developers).
This results in a sharper image without residual colorless
dyes waiting to change.  You do have to put up with the speed being
slow and the fact that you can't process it yourself.  (Well, you
can't process it yourself easily.  The chemical control lab costs
would drive most people under, the chemistry doesn't come in easy
to use boxes.)

I use Kodachrome unless speed is a factor.

		Paul Hyder  { ...tektronix!tekecs!hyder }
		   [Guess 5 years as a Tech Rep in the Photo Industry
		    wasn't a waste after all.]