• Update on Original Kodachrome Speed!

    From cinemad@21:1/5 to cinemad on Mon Sep 11 23:57:36 2017
    On Wednesday, 26 August 2009 19:47:19 UTC+10, cinemad wrote:
    I found the following in the September 1936 American Cinematographer
    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
    process gave satisfactory results on cameras that were correctly
    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
    Number "9120" and below are old emulsion numbers and require a Weston
    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.

    Peter Mason

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