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From: hyder@hpfcpkh.UUCP
Newsgroups: net.rec.photo
Subject: Re: Kodachrome vs. Ektachrome
Message-ID: <3600002@hpfcpkh.UUCP>
Date: Fri, 8-Jun-84 09:36:00 EDT
Article-I.D.: hpfcpkh.3600002
Posted: Fri Jun  8 09:36:00 1984
Date-Received: Sat, 30-Jun-84 06:21:56 EDT
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Nf-From: hpfcpkh!hyder    Jun 25 08:36:00 1984

The difference between Kodachrome and Ektachrome is one of how
the color dyes are included.  In Ektachrome they are in the
film at manufacture and the processing causes them to become
colored. (The coloration reaction is reversable, back to a
colorless coupler, so they fade in the presence of oxygen.)

Kodachrome is a three layer film with coupling sites coated into
the emulsion but no color couplers.  The couplers are in the
chemistry. (Yes, that means three color developers instead of one.
They are sort of pretty when you look at them.)  The dyes are not
the product of the processing reaction and are quite a bit more
stable.

Why not do Kodachrome at home?  The chemistry is complex, not
mass produced, and hard to control.  An analytical chemist on the
staff is critical to these processes.  The base components are
available only in large quantities and the machines to process it
were $0.5Million last time I checked.

Kodachrome is processed by Kodak, Fox Stanley, Fotomat, Berkey,
Nashua, ... (i.e. the larger labs that need the job done and have 
the money to invest for a long term return.)  With color coupler
recovery, the cost to process a roll of Kodachrome is less than
$.25(twenty five cents).  All you need is the set up costs
and lots of film to process, the lines are hardest to control if
they're not used enough.

One other note, Kodachrome has a color balance that is a little
more toward the red side.  Great for mountains, not too good for
beaches or deserts. (Unless you like things warm looking.)

Me, I shoot Kodachrome and send it to Kodak.  The control is 
the best, and you get to pay for that fact.  Most of the labs
do a reasonable job, try them if Kodak prices are too much for
you.
		Paul Hyder { ...!hplabs!hpfcla!hyder }