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Was Orthchromatic Film Orthochromatic?


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#1 Peter J Mason

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Posted 28 May 2010 - 01:44 AM

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
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#2 David Mullen ASC

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Posted 28 May 2010 - 01:51 PM

Kodak's "ortho" (Greek for "correct" I think) was an improvement over their original stocks, which were only blue sensitive. Ortho was blue-green sensitive. It HAD to be because the three-strip Technicolor camera in 1935 used blue-sensitive stock to record the blue record, panchromatic for the red record, and ortho stock for the green record. If the ortho stock had no green sensitivity, it would have been useless since all other wavelengths were filtered out before reaching the stock.
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#3 Bruce Watson

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Posted 28 May 2010 - 04:47 PM

I come at this from the still photography perspective. Same emulsions, different formats.

What I remember is that there isn't a hard and fast definition for what "orthochromatic" really means. IOW, it means somewhat different things to different people. What most people agree on is that ortho films are unbalanced. That is, they are biased toward the blue end of the visual spectrum. Very blue sensitive, with sensitivity falling as the wavelengths get longer until there is little to no sensitivity at the red end of the spectrum.

The classic look of an ortho film shot outside is the white skies. The films were so sensitive to blue that the blue skies really exposed well -- to the point that you usually couldn't tell the difference between the bright blue skies and the white fluffy clouds in those skies -- it all looks white in the final image.

Over time we learned more about how to make films and emulsions. We learned how to make sensitizing dyes that would improve the "low end" of emulsions (the red end). We learned how to use multiple coatings to get multiple layers on the film, each layer with it's own properties. It's been decades since anyone made a single layer B&W film for example.

Panchromatic films (balanced response across the entire visual spectrum, more or less) became fairly widespread in the 1920s IIRC. This new technology was widely embraced.

In the OP, Mr. Mohr stated a preference for the Dupont film. This is what DPs do -- decide what technologies to use to capture their vision of what the film should look like. I don't see anything particularly controversial about his choice.
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#4 Charles MacDonald

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Posted 28 May 2010 - 07:52 PM

The dyes used to extend the colour sensitivity have changed greatly over the years.

Early films were developed by inspection under a red safe-light. AS dyes were added to spread out the spectral sensitivity, each new version was considered "Orthochromatic" as it was MORE "correct". the catch was that the safelight requirements would have been more fussy.

I am sure that the first few Pancro films did not cover all visible red light.
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#5 Peter J Mason

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Posted 29 May 2010 - 12:29 AM

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


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#6 Peter J Mason

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Posted 29 May 2010 - 12:32 AM

Kodak's "ortho" (Greek for "correct" I think) was an improvement over their original stocks, which were only blue sensitive. Ortho was blue-green sensitive. It HAD to be because the three-strip Technicolor camera in 1935 used blue-sensitive stock to record the blue record, panchromatic for the red record, and ortho stock for the green record. If the ortho stock had no green sensitivity, it would have been useless since all other wavelengths were filtered out before reaching the stock.


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#7 peter t mason

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Posted 29 May 2010 - 12:44 AM

in line 10 of my post from yesterday there is a mistake. The line should read:

LM: They wanted you to use Eastman Panchromatic, you wanted to use Dupont ortho.
What about Eastman ortho at the time?

Also in the title to this article the second "O" from the first "Orthochromatic" is missing.
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#8 Peter J Mason

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Posted 29 May 2010 - 12:56 AM

Kodak's "ortho" (Greek for "correct" I think) was an improvement over their original stocks, which were only blue sensitive. Ortho was blue-green sensitive. It HAD to be because the three-strip Technicolor camera in 1935 used blue-sensitive stock to record the blue record, panchromatic for the red record, and ortho stock for the green record. If the ortho stock had no green sensitivity, it would have been useless since all other wavelengths were filtered out before reaching the stock.


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#9 Peter J Mason

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Posted 29 May 2010 - 01:44 AM

Kodak's "ortho" (Greek for "correct" I think) was an improvement over their original stocks, which were only blue sensitive. Ortho was blue-green sensitive. It HAD to be because the three-strip Technicolor camera in 1935 used blue-sensitive stock to record the blue record, panchromatic for the red record, and ortho stock for the green record. If the ortho stock had no green sensitivity, it would have been useless since all other wavelengths were filtered out before reaching the stock.


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
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#10 Brian Pritchard

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Posted 29 May 2010 - 12:31 PM

You can download an Eastman Kodak Booklet 'Photography of Colored Objects' dated 1919, from the Internet Archive.

Although this booklet is concerned with still photograpic plates I am sure the information would apply to films.
In the boklet it states that although orthochromatic plates are sensitive to green the sensitivity is 1/40 compared to the blue. It recomends the use of a yellow filter to reduce the sensitivity of the plate to blue.

It also says that panchromatic plates have a much higher sensitivity to blue than to the green and red. The blue sensitivity is 7/8 and the green and red 1/16 each. Again it suggests the use of a yellow filter to balance the sensitivity.

It would be interesting to know if movie cameramen used a yellow filter or accepted the lack of green sensitivity.
Brian
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#11 Leo Anthony Vale

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Posted 29 May 2010 - 02:22 PM


I am sure that the first few Pancro films did not cover all visible red light.


The 1939 edition of 'The AC Handbook's film stock section lists the speed difference between the daylight and tungsten exposures for the various panchromatic stocks as 2/3 of a stop compared to today's 1/3 stop.

Gaevert B/W stocks from the 50s also had a 2/3 stop difference between daylight and tungsten exposures.
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#12 Peter J Mason

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Posted 30 May 2010 - 01:00 AM

I have incorporated a few minor corrections here to my original post on 28 May 2010. P. 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. What about Eastman 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 to the 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


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