Color film that's both positive (slides) and negative?

Donald Qualls · Jun 10, 2020

Years ago, there was 35mm color film sold at very good prices that was advertised as offering both prints and slides from the same roll -- but only if you had it processed by the seller, either by mail or at one of their parking lot kiosks. I now know this was one of the early ventures in bringing cine films to still photography, it was remjet backed ECN-2 film and they would *print* it to a "release positive" film to provide the slides, as well as printing to whatever color print paper was in use then (this was the 1980ss, C-41 was new).

I was thinking about this film the other day, along with some of the other cine stocks that are now showing up from vendors like Film Photography Project -- and it occurred to me that the main reason we have the distinction between slide film and color negative is a quirk of the early color printing papers (a strong color cast) that requires color negative film be formulated with the familiar orange mask.

If color film were being reinvented now, with modern know-how, would it be possible to create color print paper that doesn't have that cast, that produces a color-true negative image (with, presumably, a color-true positive if processed by reversal), allowing for a film that could be either positive slides or color negatives (or B&W negatives or slides, for that matter, since it wouldnt' need a mask) depending on processing choice?

In other words, might the long-term future of still film include a convergence of the three kinds we have now, along with the similar options available in cine stocks, into a single film, maybe in multiple speeds but otherwise all the same? Economies of scale would surely apply; it'd be cheaper to make one stock for everything than to run multiple production lines.

Is this even technically possible, essentially coating paper with Ektachrome type emulsion, and taking everything from there?

MattKing · Jun 10, 2020

The need for the colour mask actually arises because of the characteristics of the colour emulsion in the negative, not the print material. The mask corrects the behavior of the colour dyes in the negative. The paper is then designed to respond to the resulting corrected "package".
The mask is, of course, variable with the image. For example the mask is different where the original is green than where the image is blue.
The mask isn't necessary for ECN type negative materials, because of their inherently low contrast and because motion pictures aren't as demanding with respect to colour fidelity.
Your idea of convergence is one that has been bandied around here before. The difficulties come from the contrast behaviors of the various media, as well as the need for that correcting mask for good colour fidelity in a negative positive workflow.
A positive positive workflow doesn't have the capacity for colour and tone fidelity that a negative positive workflow does.
All that being said, I agree that a material like the old Seattle Film Works ECN (and predecessor) material would be a good option for an amateur oriented market. Particularly if the motion picture print material used to create the slides could be made with more longevity in mind - it certainly wasn't when movies were distributed to theatres on that stock. I doubt that the volumes are there.

AgX · Jun 10, 2020

Donald Qualls said:
...and it occurred to me that the main reason we have the distinction between slide film and color negative is a quirk of the early color printing papers (a strong color cast) that requires color negative film be formulated with the familiar orange mask.

It is the other way round: the paper is sensitized that way as the taking film has a mask.
But yes, the film got that mask as its image has to be processed with the dye deficiencies not only of the taking film but also that of the paper (or print film). In a hybrid workflow that second stage of deficiencies falls away, and the urge for a mask would be less.

But here at Apug we better stay in our true analog world.

Paul Howell · Jun 10, 2020

I shot a few rolls of Seattle Film works in the 70s, seemed like a good bargain, prints, slides and negatives and a replacement roll of film. The results were not so good, the prints were ok, the slides thin, and have not lasted, all are faded beyond being scanned. Maybe with new digital technology the process could be improved, not sure if Kodak makes the copy film, as theaters digital, maybe some for the under developed world.

Donald Qualls · Jun 10, 2020

Modern ECN-2 films process as well in C-41 -- The Cinestill stocks are apparently special in some way, they don't have remjet, but there are lots of folks shooting Visions3 stocks and processing in C-41 and getting good results. How much of that is post-process, whether filters or digital, I don't know, but those films apparently also have the orange mask. I know cross-processing E-6 in C-41 color dev produces "odd" colors, but that's also a different developing agent -- E-6 is CD-3, as I recall, instead of CD-4 in C-41. What do you get if you process Ektachrome or Fuji slide films in E-6 color dev without the first developer?

Oh, full black slides, because it's fogging developer. So, say, make up E-6 color dev from ingredients, and leave out the fogging agent (stannous chloride?)?

Guess it doesn't matter, since there isn't a color paper that's not biased for the orange mask. I was envisioning a color system where the different segments -- film and paper, negative, direct positive (film or paper), B&W and color, could be mixed and matched. No realistic expectation of anything paying for the development to create this, of course, just dreaming... .

iandvaag · Jun 10, 2020

MattKing said:
The mask isn't necessary for ECN type negative materials

I believe that most ECN type negative materials actually do have a mask (apart from the print films which are designed for human viewing). I'm not sure about their digital color intermediate film [XX54], but their other two intermediate stocks [XX42 & XX73] are masked, as are all of their camera negative films.

Donald Qualls said:
Guess it doesn't matter, since there isn't a color paper that's not biased for the orange mask.

If you had an unmasked film, you could print it onto modern colour papers by adjusting the filter pack. The effect of the mask is that there is a uniform excess density for one or two of the colours. If you dial in a filter pack that makes a masked negative appear neutral, than functionally (from a broad colour balance perspective), you have an unmasked negative. The mask is there to compensate for unwanted dye absorptions which cause colour impurity. If you were to design a new dual neg & pos colour film, these colour impurity problems can be partially solved by other means than a mask (as is done in color positive films.) These methods are less effective than a mask, however. But you won't have broad colour balance or bias problems if you adjust the filter pack.

As Matt hit on, I think the main problem in designing a colour film that can be processed both as a neg and reversal processed is that the emulsions are inherently designed to different contrasts, and there's a limit to how much you can change that by tweaking the developer formulations. So you can design a high contrast emulsion, and give up latitude when you shoot it as a negative (requiring that you expose it with similar constraints as slide film). Alternatively, you could develop a low contrast emulsion, but you might end up with a washed out low-contrast positive that isn't very appealing to look at or project. This is just my speculation. I'm sure there are other complicating chemical factors that would also present challenges in creating a unified neg & pos film.

I think the ultimate in colour imaging would be the ability to use the best current generation negative films (Portra, Ektar) and use that as a negative. Then if you want slides, there should be some unmasked "print film" that is designed to work with the slightly higher contrast still films to give an jaw-dropping colour positive. Essentially ECN/ECP, but with smaller minimum orders, in still formats, and with C-41 processing. For this I would gladly give up slide film, and for that sacrifice, I would end up with even better slides!

MattKing · Jun 10, 2020

iandvaag said:
I believe that most ECN type negative materials actually do have a mask (apart from the print films which are designed for human viewing). I'm not sure about their digital color intermediate film [XX54], but their other two intermediate stocks [XX42 & XX73] are masked, as are all of their camera negative films.

Thanks for the correction Ian - I have been working with a misunderstanding about current ECN materials/Cinestill films.

cmacd123 · Jun 10, 2020

MattKing said:
The need for the colour mask actually arises because of the characteristics of the colour emulsion in the negative, not the print material. The mask corrects the behavior of the colour dyes in the negative. The paper is then designed to respond to the resulting corrected "package".
The mask is, of course, variable with the image. For example the mask is different where the original is green than where the image is blue.
The mask isn't necessary for ECN type negative materials, because of their inherently low contrast and because motion pictures aren't as demanding with respect to colour fidelity.

the Mask is present and is needed on motion pciture materials. The folks who shot movie film are proably far more critical of the results than any still photographer is likely to be.

the mask is a result of two different couplers a yellow one and a magenta one, which correct for dyes in the layers that they are responsible for adsorbing too much yellow or magenta light. where the defective dye forms, the mask layers each become clear become clear and so the entire film has a uniform absorption. the mask is automaticsly dials out on printing.

the traditional Motion picture process has teh camera negative printed as a master positive, which is then used to make a duplicate negative. ALL THREE of those films have an orange mask. You can get the data sheets on the Kodak motion picture site under products, lab films. see www.kodak.com/go/motion

back in teh day, I used a fair amount of the Eastman colour from the various labs. both the 5254 process ECN and 5247 Process ECN2 - ECN2 has the same sort of changes as going from C-22 to C-41.

I even did some home developing of Eastman colour using the teaspoon formulas that were published at the time by Dale Neville. the remjet was a pain. I did not ever use the intermediate stocks.

one "problem" in those days was that the Aim Gamma for movie film is lower - to allow for all the stages before you get the final print, so while the ECN negatives were quite compatible with Colour print paper- even at a minilab, the resulting paper prints were lower contrast than if one had skipped the bother and used Kodacolor. Likewise, some of the labs would develop kodacolor and then print on movie stock and those slides would have very high contrast.

finally since the slides were contact prints, the emulsion was on the opposite side compared to a normal ektachrome slide, and so the "curved field" lens on a standard slide projector would show soft edges, and I have to buy an ektagraphic projector lens.

cmacd123 · Jun 10, 2020

everyone should read this page from a movie fellow, http://www.brianpritchard.com/why_colour_negative_is_orange.htm

then we can stop hearing about wanting to eliminate Masks, the Mask is your friend.

Donald Qualls · Jun 10, 2020

cmacd123 said:
the Mask is your friend.

The mask is your friend when you're printing on current RA-4 papers, but not if you decide after shooting that you'd really rather have slides, and don't have easy access to a release positive or intermediate positive stock.

foc · Jun 10, 2020

cmacd123 said:
everyone should read this page from a movie fellow, http://www.brianpritchard.com/why_colour_negative_is_orange.htm

then we can stop hearing about wanting to eliminate Masks, the Mask is your friend.

Very interesting read.

Agfa produced an unmasked colour film in the 1950s and 1960s, a few details about it are here:
https://www.photomemorabilia.co.uk/Colour_Darkroom/Early_Agfa.html#anchorAgfa15o

cmacd123 · Jun 10, 2020

Donald Qualls said:
The mask is your friend when you're printing on current RA-4 papers, but not if you decide after shooting that you'd really rather have slides, and don't have easy access to a release positive or intermediate positive stock.

there is always cross processing ektachrome I guess. The intermediate positive stock is also masked fro the same reason the Negative is so that would not help you.

if you really want some positive print film, you can order one roll of
KODAK VISION Color Print Film / 2383 / VCP666 / 35 mm x 2000 ft roll / On Core / KS-1870
CAT 8274037
price in the Jan 02 2020 catalogue was just under 300.00 dollars US for us shipment, plus postage of course. stuff works out to about 15 cents a foot.

ebay seller in Hong Kong will sell you 100 ft for 60 bucks http://www.ebay.ca/itm/233457318412

2383 does NOT have REM jet so it will posibly work in in normal c-41 process. although it is designed for ECP2 without the rem jet removal step (the process was chaged to save water.)

cmacd123 · Jun 10, 2020

foc said:
Very interesting read.

Agfa produced an unmasked colour film in the 1950s and 1960s, a few details about it are here:
https://www.photomemorabilia.co.uk/Colour_Darkroom/Early_Agfa.html#anchorAgfa15o

and as soon as they could (kodak's patents and all) they switched to a masked system.

AgX · Jun 11, 2020

iandvaag said:
I believe that most ECN type negative materials actually do have a mask (apart from the print films which are designed for human viewing).

If you had an unmasked film, you could print it onto modern colour papers by adjusting the filter pack.

-) yes

-) the approach advised by colour paper manufacturer was to use a mask-substituting filter. Alternatively to use an unexposed, but processed piece of masked film.

Donald Qualls · Jun 11, 2020

cmacd123 said:
there is always cross processing ektachrome I guess.

But then you get the funky cross-process colors after you invert, or you have to make up a very unusual filter pack to print it (and probably still get crossovers -- due to the lack of mask, which is anti-image in the yellow and magenta layers, according to earlier posts).

cmacd123 · Jun 11, 2020

AgX said:
-) yes

-) the approach advised by colour paper manufacturer was to use a mask-substituting filter. Alternatively to use an unexposed, but processed piece of masked film.

the default when printing is generally to have both magenta and yellow filters, so unmasked film would just need those filters dialed up a notch. enough to make up for the mask in the unexposed film. the cross over and false color casts that the mask is intended to solve would still be there of course.

AgX · Jun 11, 2020

Well as said, film manufacturers advised to use a mask-substituting filter.

thuggins · Jun 16, 2020

Rollei Digibase was an unmasked negative film intended for workflows that had no need for the mask. It produced lovely slides when processed in E6. Crossbird may or may not be the same emulsion. It was originally sold as a slide film, but now marketed for cross processing, probably to increase the market. I just shot a roll of it over the weekend and am always pleased with the unique and "classic" look to the slides.

I've mentioned before that the future of color film should be an unmasked emulsion that could be processed as negatives or trannies.

Alan Edward Klein · Jun 16, 2020

MattKing said:
The need for the colour mask actually arises because of the characteristics of the colour emulsion in the negative, not the print material. The mask corrects the behavior of the colour dyes in the negative. The paper is then designed to respond to the resulting corrected "package".
The mask is, of course, variable with the image. For example the mask is different where the original is green than where the image is blue.
The mask isn't necessary for ECN type negative materials, because of their inherently low contrast and because motion pictures aren't as demanding with respect to colour fidelity.
Your idea of convergence is one that has been bandied around here before. The difficulties come from the contrast behaviors of the various media, as well as the need for that correcting mask for good colour fidelity in a negative positive workflow.
A positive positive workflow doesn't have the capacity for colour and tone fidelity that a negative positive workflow does.
All that being said, I agree that a material like the old Seattle Film Works ECN (and predecessor) material would be a good option for an amateur oriented market. Particularly if the motion picture print material used to create the slides could be made with more longevity in mind - it certainly wasn't when movies were distributed to theatres on that stock. I doubt that the volumes are there.

Matt, if the mask varies depending on what is photographed, how do scanners work where you dial in the film model?

How do Epson scanners adjust for negative color film where you only check off negative film, not the manufacturer?

MattKing · Jun 16, 2020

Alan Edward Klein said:
Matt, if the mask varies depending on what is photographed, how do scanners work where you dial in the film model?

How do Epson scanners adjust for negative color film where you only check off negative film, not the manufacturer?

If properly set up, the scanners and associated software work the same way that RA-4 darkroom printing paper works - they respond to the entire package - the image plus the mask. The mask corrects the impurities in the dyes used to create the image, and the two together only need the inversion and simple filtration built into the paper to remove the orange cast.

Alan Edward Klein · Jun 16, 2020

MattKing said:
If properly set up, the scanners and associated software work the same way that RA-4 darkroom printing paper works - they respond to the entire package - the image plus the mask. The mask corrects the impurities in the dyes used to create the image, and the two together only need the inversion and simple filtration built into the paper to remove the orange cast.

I don;t understand your point in the earlier post: "The mask is, of course, variable with the image. For example the mask is different where the original is green than where the image is blue."

How does it know whether you shot green or blue?

MattKing · Jun 16, 2020

Alan Edward Klein said:
I don;t understand your point in the earlier post: "The mask is, of course, variable with the image. For example the mask is different where the original is green than where the image is blue."

How does it know whether you shot green or blue?

It doesn't - the mask is formed as part of the developing process, and its nature varies with the adjacent dyes that form part of the image.
If your subject is, for example, yellow, the corresponding blue dyes are formed at that location in the negative and, at the same time, additional dyes that provide the necessary correction are formed at the same location.

thuggins · Jun 16, 2020

MattKing said:
the mask is formed as part of the developing process, and its nature varies with the adjacent dyes that form part of the image.

No, it is not. This topic has been discussed many times here and easy to test. The mask is in the base. It is not associated with the dyes, it is not created during the development process, and there is no way to remove it. Just fix a piece of unexposed, undeveloped film and it will definitely come out orange.

I am no expert on negative film and haven't shot negatives for years. But logic would indicate the mask is related to the printing process. Getting vibrant and realistic colors with just the dyes can't be that hard. Transparency film does it all the time and there have been numerous palettes, saturation and other variations produced in countless brands of slide films over the years.

RPC · Jun 16, 2020

thuggins said:
No, it is not. This topic has been discussed many times here and easy to test. The mask is in the base. It is not associated with the dyes, it is not created during the development process, and there is no way to remove it. Just fix a piece of unexposed, undeveloped film and it will definitely come out orange.

You are wrong. The mask is absolutely formed during development, from residual dye couplers, that is, dye couplers that do not form dyes during development. The dye couplers are colored at the factory. The orange color you see after fixing in your example is unexposed, undeveloped dye coupler.

The orange color you see in exposed, processed film consists of two things. the dye color impurities, which vary over the image and collectively form an unwanted negative orange image (which forms along with the main dye image), and the mask, which is a positive orange image (formed from residual dye coupler) and also varies over the image opposite to the dye impurity image.

They mask and cancel each other, forming a uniform orange color all over the negative which is uniformly filtered out or offset during printing or scanning, effectively removing both the effects of the mask and the dye impurities, leaving the printed or scanned image with no impurities from the negative.

Since the mask is necessary to correct dye impurities, any negative film without one will print with unwanted color errors.

MattKing · Jun 16, 2020

thuggins said:
No, it is not. This topic has been discussed many times here and easy to test. The mask is in the base. It is not associated with the dyes, it is not created during the development process, and there is no way to remove it. Just fix a piece of unexposed, undeveloped film and it will definitely come out orange.

I refer you to PE's numerous posts on the subject here over the years, and Bob Shanebrook's ("laser" here on Photrio) excellent publication "Making Kodak Film".
In particular, the table on pages 10-11 of the 1st edition, and the notes on page 12 of that edition.
Each row on that table corresponds to a layer of colour negative film - including the backing. On rows 15, 14, 11, 10, 9, 7, 6 and 5 of the table one of the numerous colour sensitive emulsion components is described. In each case there is gelatin, silver halide and dye. In each case there is one or more "colour" Image Dye Coupler (where "colour" refers to one of Yellow, Cyan or Magenta). Each Coupler is described as "Reacts with oxidized developer to form dye image."
And with the exception of row 7 - the row that deals with the Fast Red Sensitive Emulsion and refers to the Cyan Image Dye Coupler - there is one or more separate "Colour" Dye Coupler that "Forms dye image to correct colour errors".
And then on page 12: "Dye masks correct for the light absorption of other dyes. The strength of the mask depends on local exposure." (Emphasis added)

Color film that's both positive (slides) and negative?

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