On Wednesday, 26 August 2009 19:47:19 UTC+10, cinemad wrote:

I found the following in the September 1936 American Cinematographer
Magazine
on page 396:

Kodachrome Speed

There have been two important changes in Kodachrome Film made during
the past
few weeks.These changes are called to your attention so that you will immediately
know the correct course to follow with regard to the use of this

particular film.

So the original Kodachrome film speed was 4 WESTON or 5ASA.

Change No. 1

As supplied to the market during the last six months, Kodachrome Film required
a Weston speed of 4 Scheine 15. This film speed and the original
developing
process gave satisfactory results on cameras that were correctly
calibrated.
A new development process has recently been introduced which changes
the speed
of the original emulsion from a Weston speed of 4-15 Scheine to a
Weston speed
of 6-17 Scheine.
All of the above speeds referred to are for Daylight. No information
is available at the
moment regarding Tungsten light.
Note that the above change was a change to the development process and
not a
change due to a change in the film itself.

Change No. 2

Within the last few days a new Kodachrome emulsion Film has been
introduced on
the market. This new emulsion, when developed by the new process,
increases the
speed of this film from the original value of 4 Scheine 15 to a new
value of approx-
imately 10 Scheine 19. This value is tentative and subject to revision
when further
tests are completed. These values are for Daylight, again there being
no data
available at the moment for Tungsten.
The new emulsion can be identified by noting the emulsion number.
Numbers above
"9120" indicate the new emulsion, which require the higher Weston
speed.
Number "9120" and below are old emulsion numbers and require a Weston
speed
of 6 Scheine 17 if developed by the new process.

Also in the February 1937 SMPE Journal on page 173 there is an article "Medical Motion
Pictures in Color" which was presented at the Fall meeting at
Rochester N.Y. (12th-15th
October 1936). This article is mainly concerned with the use of the
new Type A Kodachrome
for producing medical motion pictures.
After the paper was presented by Mr. R.P. Schwartz from the University
of Rochester School
of Medicine and Mr. H. B. Tuttle from Eastman Kodak. At the end of the
paper a 16mm film was
presented that was filmed on the type "A" Kodachrome. After the film
was shown there was a
discussion and Mr. Tuttle stated the following:

"When making the picture, the field was illuminated with one medical spotlamp,and exposures
were made with an aperture of f/4, on the artificial-light type of
film that has been available for
the past few months. Within the past week or so, new fast artificial-
light film has been placed
upon the market that is twice as fast as the old film, so that the
same scene can be filmed today
at f/5.6 with one medical spotlight equipped with a 500-watt, 100-105
volt lamp."

It would appear then, the original speed of both Daylight balanced
Kodachrome and Type "A"
Kodachrome was effectively doubled in Sept-October 1936, two years
before the change to to the
Selective Exposure process in October 1938.

Regards,
Peter Mason

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