Peter J Mason

David, The original Technicolor system that was in use in 1935 did not use a purely blue sensitive film. It then used a standard Bi-pack consisting of an orthochromatic front film and a panchromatic rear film(Eastman Supersensitive Negative 1217 but using its other hat I believe it was referred to as 1220) When they improved the Technicolor system in late 1938 and more than doubled the speed, they eliminated the magenta filter and then used a special purely blue-sensitive film as the front blue sensitive film and Eastman Plus X negative 1231 as the rear red sensitive film. As part of the new tri-pack the Plus X film was given code number 1237, and the green and blue sensitive films 1238 and 1239 respectively. Whereas the original separate green sensitive film was panchromatic in the new system a new highly green sensitive film orthochromatic film was used making it possible to eliminate the green filter and replace it with a yellow filter which allowed more than double the amount of light to reach the film. The filter factor for the original green filter was 6 whereas the yellow filter had a factor of 2.5 and was thus much more efficient. Then in 1951 the new Dichroic prism system was introduced that effectively doubled the speed from 8 Weston to 16 Weston(20 ASA). Now in relation to the original topic, Dr. C.E. Kenneth Mees who was the Director of Research and Development for Eastman Kodak states very clearly in his article that the black and white negative (1201) that was the standard production negative used in Hollywood during the Silent era was only sensitive to blue, violet and ultra-violet. It was not a sensitized emulsion and therefore was NOT Orthochromatic. Despite claims by some people to the contrary "orthochromatic" has a very clear meaning, a film that has been sensitized so that the sensitivity is extended to the green and yellow portion of the spectrum to just under 600 nanometers is orthochromatic. The original sensitizers were derived from quinoline. The green sensitizers were isocyanines(for orthchromatic film) and the red sensitizers generally used was pinacyanol(for panchromatic film).Later on other sensitizers were developed but the point is none of these sensitizers were used in the Eastman Motion Picture Film Negative 1201. The film was purely "blue sensitive". This was why Hal Mohr was complaining about it and states his preference for the Dupont Ortho which was a genuine Orthchromatic film rather than the "so called" Eastman Orhochromatic film which was in fact Blue Sensitive only. Regards, Peter Mason

In the Art of the Cinematographer by Leonard Maltin(1978) there is an interview with Hal Mohr on page 75. On page 85 of that interview Leonard Maltin asks Mohr various questions about the film stocks available in the late twenties about the time he was photographing NOAH'S ARK(1929): LM: Can you explain about the different film stocks at this time? Mohr: In the orthochromatic stages before panchromatic film became the thing to use, because of sound, there was a competitive film made by the Dupont Film. It was a true orthochromatic film, and by true orthochromatic it did have yellow sensitivity and certain qualities that the so called orthochromatic film made by Eastman did not have. In my opinon it was a superior film. Further on in the interview Maltin asks him about his choice of film stock for NOAH'S ARK(1929): LM: They wanted you to use Eastman Panchromatic, you wanted to use Dupont Ortho at the time? Mohr: Eastman ortho was not ortho. It was a black and white film but it had no sensitivity at the yellow end of the spectrum.I don't know what you'd call it. On the old orthochromatic film, if you were to put a red filter on it to try to control the sky you got nothing. But on the Dupont I could use a K3 filter or something and get blue sky held down, and the white clouds would come through. K3 was a very heavy amber filter. In the article History of Professional Black-and-White Motion picture Film by Dr. C.E. Kenneth Mees, former Director of Research and Development for the Eastman Kodak Company, Dr. Mees states on page 134 of the SMPTE article of October 1954: "In 1916, when the Society of Motion Picture Engineers was formed, only two motion picture films were available---a negative film for use in the camera and a positive film for making prints. The negative film was sensitive to blue, violet and ultraviolet light and it was necessary to expose it outdoors by daylight or indoors by the use of arc lamps." In Motion picture Laboratory Practice and Characteristics of Eastman Motion Picture Films, EASTMAN KODAK COMPANY, Rochester, N.Y. 1936 it states on page 42: Eastman Negative Motion Picture Film (no. 1201) This is a high speed blue sensitive negative material, and is used where the rendering of color is not important and extreme speed is not required. On page 44 it states: Since Eastman Negative Motion Picture film is not color-sensitised, its sensitiveness(figure 18) extends from the ultra-violet through the violet and blue-green. Apparently most of the major studios were using Eastman b/w negative at the time and since all the available information suggests it was a purely blue-sensitive film NOT Orthochromatic film. Hal Mohr was obviously aware of this(Eastman Ortho is not Ortho) so surely other DPs would have also been aware of this also. Why didn't they use the Dupont negative which according to Mohr was a genuine orthochromatic film. Dr. Mees gives further information in his article that in 1925 the name of the film was changed to Motion Picture Negative Film Par Speed to distinguish it from other Eastman films such as the high speed b/w negative that was introduce in the twenties. In 1928 Eastman began the practice of assigning 4 digit code numbers to its films and Motion Picture negative Film Par Speed was given code number 1201. Dr. Mees states that this film continuesd essentially unchanged until it was discontinued in July 1942.(Apparently in later years it was used mainly as a laboratory film.) The Art of the Cinematographer is available to read ont the internet. If you wish to easily find the parts relevant to this post just type in "Eastman Panchromatic Film type 2" and it should come up in the first 10-12 results. Regards, Peter Mason

Apparently there was an AMPAS bulletin released on 25 March 1932 regarding the new aspect ratio. Does anybody have access to this?

According to information in the British Kinematography Journal of July 1956(page 20) the 1.37:1 ratio was chosen to compensate for an average projection angle of 14 degrees. This means that a 1.37:1 ratio projected downwards at 14 degrees will give a projected image of 1.33:1 ratio. This information was stated as coming from a SMPTE booklet . So exactly the same projection angle as the GRAND mentioned by John Sprung above. Is there anybody out there who can do the math?

Does anybody know the reason why the original Silent ratio of 1.33:1 was increased to 1.37:1 when the sound Academy Aperture was introduced in 1932? Regards, Peter Mason

The original Technicolor 3-strip process(1932) had a speed of 3-4 Weston which is equivalent to 4-5 ASA in present day terms. In late 1938 beginning with The Wizard of OZ (1939) (Not Gone With the Wind(1939) as most people erroneously state) Technicolor increased the speed of the process to 8 Weston(10 ASA) and the process retained this speed until 1951 when the Dichroic Prism was introduced and the Technicolor film speed was increased to 16 Weston(20 ASA). There were no further film speed increases after this time and reports that Technicolor attained a speed of 50 ASA in the mid fifties are incorrect. Regards, Peter Mason