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Film Stock without orange mask


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Hi,

 

In the November issue of Film & Video, I read the following by Bill Bennett, ASC:

 

"...from what I understand you can increase the latitude of film and also lower the gamma curve considerably by eliminating the orange mask, which is necessary for optical printing. I think you'd essentially have a 1,000-speed film with the grain of a current 200-speed emulsion."

 

If this is true, why hasn't Kodak made such a film?

 

John Mastrogiacomo

Spectra Video :unsure:

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I'm not sure that Bill Bennett's speculation is entirely true. But in any case, the orange mask is there for a good reason. The dyes that are used in negative film are necessarily less than perfect: in particular, the magenta dye absorbs a little too much blue light, and the cyan absorbs a little too much green and blue.

 

So to compensate for this, the colour couplers (which are the chemicals that are converted to coloured dyes in the exposed areas, during processing), are designed so that they too absorb a little blue and green light. This means that all areas of the film abosrb some blue and green light, whether or not the couplers have been exposed and converted to dye or not. So you get an overall yellow/orange cast in the film, commonly referred to as the masking layer (though, as described, it's not a separate layer, but an integral property of the main dye layers.)

 

If the manufacturer didn't do this, you would have very poor colour reproduction, particularly poor saturation. What price 1000ASA film if the colours are no good?

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I believe the color mask though is designed to correct these difficiencies when going to print film. If the image is never printed, but scanned directly, I don't think they are needed. I don't really believe that speed would be increased much (the old Primetime stock, which was Kodak's first attempt at a color negative with no color mask, for telecine work only, was 640 ASA -- but it was grainy) but in theory transfer noise would be decreased because the telecine would not have to compensate the RGB gain levels for the color mask.

 

I've heard rumors that Kodak is considering once again a stock without the color mask for telecine and DI work only.

 

I've also heard that Fuji's color mask is less dense because of a design compromise to make less noisy telecine transfers while still allowing good prints. But this may explain some of the color reproduction differences between Kodak and Fuji and why some labs aren't used to printing it correctly -- they are basing their printer lights on Kodak's color mask.

 

Of course, color reversal stocks do not have a color mask, but then, they aren't designed for making prints off of.

 

This is from the "Story of Kodak" book:

 

By using yellow-colored magenta coupler and a salmon-colored cyan coupler, blue light was kept from degrading the intensity of the red and green layers of the negative. The result of this masking is a brick-orange negative. As Hanson explained in a 1977 speech:

 

"Thus in printing, only the cyan peak is printed, resulting in saturated yellow and magenta images that produce clean, bright reds, because the unwanted green and blue absorption of the cyan dye are cancelled out. The colored coupler has a red orange cast to it. The color is destroyed where the image is formed, but where there is no image, the colored coupler remains. Because the absorption is the same over all the picture area, the whole process negative (masked with the colored coupler) looks red orange."

 

--

 

Some of this gets a little over my head, but I believe it's meant to improve the color of the prints made off of the negative; not sure why the print stock could be the material that compensated for the excess blue absorption...

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Hi,

 

Only vaguely related topic, but are the recent low-con, high-sharpness stocks still suffering from the issue of the RGB sensitivities crossing over more and more? I'm sure I read somewhere that the purpose of the SFX200 stock was to alleviate this in the days of optical bluescreen.

 

Phil

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The colored couplers are a neat trick for dealing with a problem that is inherent to all real world chemical dyes. If you look at a graph of wavelength versus dye density, the reds, oranges, and yellows give you a nice sharp cutoff, passing a lot of the photons you want and very few of those you dont' want. But the cooler colors all have too gentle a slope to their curves, letting through more of what you don't want, and less of what you do, than the warm color dyes. This comes from something very deep in the physics of molecular bonds.

 

By leaving yellow and orange instead of clear where you don't have cyan and magenta, you shift the neutral point from gray to orange, but you get to "borrow" some of the nice sharp cutoff from the warm dyes to give to the cool colors. As a result, your print stocks and telecines have to be designed to pull that orange neutral back to gray so we can look at it. When we go through IP/IN, the intermediate stock uses the same orange mask technique, and an IP looks like a low contrast positive image with the orange on it.

 

The orange stuff lets the film do a better job of sorting photons out into red, green, and blue.

 

 

 

-- J.S.

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Does anyone have any examples of shows shot on this Primetime 640T film? I've read about the stuff, but I wouldn't be able to point it out on television. Did it reside solely in the hands of sitcoms, or were there other shows that used it too? I'm curious to see if it is grainier than say the EXR 500T of the same era or if the theory that the orange die reduces speed is indeed correct. Also, are any reruns of the shows that used it still on the air? Thanks for your help.

 

Regards.

~Karl Borowski

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I remember once some guy shot 16mm Primetime and had it printed onto regular printstock, which is "not recommended" by EKC. The look was very similar to the VNF-1 Ektachrome reversal from what I recall, grain was similar too. The grain got sort of greenish though in the shadow areas, which looked unnatural.

 

I suppose in theory you could cross process this sort of color mask free color negative film in a color reversal bath (with proper rem-jet removal) and get a normal positive image, probably a very low contrast one.

 

- G.

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I remember once some guy shot 16mm Primetime and had it printed onto regular printstock, which is "not recommended" by EKC. The look was very similar to the VNF-1 Ektachrome reversal from what I recall, grain was similar too. The grain got sort of greenish though in the shadow areas, which looked unnatural.

 

I suppose in theory you could cross process this sort of color mask free color negative film in a color reversal bath (with proper rem-jet removal) and get a normal positive image, probably a very low contrast one.

 

- G.

 

Did he do it for television? I'd really like to see what the stuff looks like. And why'd they axe it if it was so good for TV? Are a lot of obsessive-compulsive directors who at least want the ability to release anyting they shoot in a theatre still involved in television?

 

Regards.

~Karl Borowski

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It was dropped because it didn't sell well. It didn't sell well because it was considered grainy (too fast, too low-con), but the real problem was that colorists had their telecines set-up for color-masked negative and had a hard time adjusting to the stock, producing noise problems, the very problems that Primetime was supposed to be better at.

 

The other problem was that many DP's resented that Kodak basically marketed it directly to TV producers as being cheap to shoot and needing less lighting (the way Sony marketed the F900) which made them feel they were being side-stepped.

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Kodak introduced colored couplers (integral dye masking) with the first EASTMAN Color Negative Film in 1950:

 

http://www.kodak.com/country/US/en/motion/...t/chrono2.shtml

 

EASTMAN Color Negative film, 5247. 35mm. Daylight, EI 16. First Kodak incorporated-color-coupler camera negative film. Replaced by 5248 in 1952.

EASTMAN Color Print film, 5381. 35mm Incorporated color-coupler print film for printing from color negative, 5247. Replaced by 5382 in 1953.

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Kodak PRIMETIME 640T 5620/7620:

 

http://www.kodak.com/country/US/en/motion/.../tech5620.shtml

 

One show was "Chicago Hope":

 

http://www.theasc.com/magazine/oct97/emmy/pg1.htm

 

The CBS medical drama has a slightly different look this season, courtesy of a new film stock. Although Bagdonas was quite satisfied with the original version of Kodak's PrimeTime 640T that he had been using, Eastman asked him to try out the latest version of the 640T emulsion: 5620. "We agreed to test it," says the cameraman, "and it turned out to be head and shoulders above the old version. It's a T-grain stock, and it's sharper, more contrasty and just all around better-looking."

 

The new stock also spurred other changes. Whereas Bagdonas used a Tiffen Soft/FX filter on almost every shot last season, he was so pleased with the look of PrimeTime 5620 that he decided to forgo all filtration on this season's installments. He now employs much less fill on the actors' faces, lets windows blow out a bit more, and allows some of the sets' dark areas go a bit darker. "We don't worry about justifying any of our light sources," he says, "as long as we think they look right."

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  • 11 years later...

I believe the color mask though is designed to correct these difficiencies when going to print film. If the image is never printed, but scanned directly, I don't think they are needed. I don't really believe that speed would be increased much (the old Primetime stock, which was Kodak's first attempt at a color negative with no color mask, for telecine work only, was 640 ASA -- but it was grainy) but in theory transfer noise would be decreased because the telecine would not have to compensate the RGB gain levels for the color mask.

 

I've heard rumors that Kodak is considering once again a stock without the color mask for telecine and DI work only.

 

I've also heard that Fuji's color mask is less dense because of a design compromise to make less noisy telecine transfers while still allowing good prints. But this may explain some of the color reproduction differences between Kodak and Fuji and why some labs aren't used to printing it correctly -- they are basing their printer lights on Kodak's color mask.

 

Of course, color reversal stocks do not have a color mask, but then, they aren't designed for making prints off of.

 

This is from the "Story of Kodak" book:

 

By using yellow-colored magenta coupler and a salmon-colored cyan coupler, blue light was kept from degrading the intensity of the red and green layers of the negative. The result of this masking is a brick-orange negative. As Hanson explained in a 1977 speech:

 

"Thus in printing, only the cyan peak is printed, resulting in saturated yellow and magenta images that produce clean, bright reds, because the unwanted green and blue absorption of the cyan dye are cancelled out. The colored coupler has a red orange cast to it. The color is destroyed where the image is formed, but where there is no image, the colored coupler remains. Because the absorption is the same over all the picture area, the whole process negative (masked with the colored coupler) looks red orange."

 

--

 

Some of this gets a little over my head, but I believe it's meant to improve the color of the prints made off of the negative; not sure why the print stock could be the material that compensated for the excess blue absorption...

 

David,

 

>By using yellow-colored magenta coupler and a salmon-colored cyan coupler, blue light was kept from degrading the intensity of the red and green layers of the negative. The result of this masking is a brick-orange negative.

 

The 'brick-orange negative', color, are you referring about unexposed rawstock or developed negative?

 

>"Thus in printing, only the cyan peak is printed, resulting in saturated yellow and magenta images that produce clean, bright reds, because the unwanted green and blue absorption of the cyan dye are cancelled out.

 

'only the cyan peak is printed' Could you explain this? What about Magenta and Yellow? Not printed?

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Color masking is too complicated to explain any more clearly in a post, partially because even I have a hard time following it. Maybe a lab person could explain it more clearly. I was quoting the Kodak book because I don't think I could explain it more accurately.

 

I'm referring to the color of the negative after processing.

 

I think what the Kodak book was saying is that without the color mask, the cyan layer would somehow pollute the other two layers with excess green and blue, giving you less saturated colors in the print. But I'm not sure, I'd have to study it more carefully to follow the train of logic here.

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Some of you might find this of help: http://www.brianpritchard.com/why_colour_negative_is_orange.htm

There are some scans of colour negative layers with and without masking. These slides I helped to make in the 60's for a lecture by Dr R W G Hunt on colour reproduction when I worked in the Kodak Research laboratories at Harrow in England. Emulsions were specially coated as single layers to illustrate the effects of masking which cannot be seen any other way.

Brian

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