Why
did he not use the final shots with the Polachrome 35? Well, quite
honestly the quality is not first class. If you are as old as I am, you
will probably have heard of Dufaycolor slides. The Polachrome 35 is on the
same principles as Dufaycolor. It is an additive method. All other colour
transparencies are now using the subtractive method. To explain the full
details as compared with the two methods would fill this Newsletter, but
here is the general principles. With the additive method, three colour
dyes are printed over a panchromatic black and white film and the colour
dyes are in a microscopic mosaic or “reseau” There is no need to
generate colour development because the dyes are already built-in. (Cibachrome
also contained built-in dyes. but unwanted dyes are destroyed, not by
masking the unwanted colours with a reversed B&W layer as with the
additive method.). All that has to be done is to use a reversal mono-bath
gels on the black and white Polaroids. But there is a snag.
Additive screen transparencies are inefficient in terms of light passing
power. Even with the “Whites” of the image, only one third of the
possible illumination is transmitted (two thirds is absorbed by the colour
mosaic). This explains why Polaroid suggests you to have - good blackout,
a modern light-efficient projector and not to use zoom projector lenses
because they are less light-efficient Also, the pattern of the mosaic
shows up and losses the definition. I hate to think what sort of pictures
you will get if you make colour prints from Polachrome on Cibachrome!!
In the subtractive method the “whites” contain no dyes and no mosaic
screen, hence there is a much brighter slide and with better definition.
The third film, the Polagraph HG, rated at 400 A,SA, is intended to make
line drawings on transparencies. Would b€ just the job for halls,
conferences and schools where facts and figures can be prepared by
photographing computer-generated graphics and text ? New information could
be made and displayed on the screen even during the session.
Polaroid also make a special device for this purpose It is called the
Palette Computer Image Recorder. It sounds expensive and it is expensive.
It will set you back £1240 + VAT With the Palette, you can make
transparencies such as coloured bar-graphs even though the computer is
mono only. ’There is a small mono view screen inside the Palette, and
there is tri-colour filter wheel to simulate the ‘various colours you
require in the graphics.
A feature of the system IS the high level of security. From the
generation of the text, and the graphics to the projection on the big
screen, complete progress can be carried out personally by the user or,
cutting out the risk of classified information falling into the wrong
hands.
I can hardly imagine, though, that many members of the C R.C are going
to rush out and buy this equipment to make colour titles for their next
audio-visual. George Sparkes, (Area 22) with his excellent computer
titles, done at a minimum cost, has beaten Pola by a mile for our
purposes.
Area
13. News.
Area
Leader, Margary Meadows writes to report that they held their Annual
meeting on the 16th of November Everyone enjoyed themselves and along with
a good ‘natter’ held a slide competition, The winner was Bert
Platt from Sawbnidgeworth.
Margary
would like to give thanks to Roger Wigley who volunteered to take over the
judging of the competition when the judge booked was unable to come at.
the last minute.
Along
with this Margary showed some more slides of her Kenyan Wildlife venture,
together with a selection of miscellaneous 10 x 8 prints, and Frank White
also brought along some slides and prints.
=================================
As
the Didcot Open Meeting appears now to become an Annual event and A.G M it
is hoped that we will see more of Margary’s excellent Safari prints It
is much too early to be able to set a date yet, but it will be around the
first two weeks in June 86. Please keep this in mind and try to be able to
come along and bring some of your work
and meet many of the people you read only about in this Newsletter.