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

RPC said:

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.

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It appears we have been reduced to arguing semantics. "The orange color you see after fixing in your example is unexposed, undeveloped dye coupler." is double talk for "there is an orange base". Whether that is done as an orange dye (not a dye coupler) that is always in the emulsion, or an orange dye in the base before the emulsion is added it is still not part of the color dye couplers.

Refer to this thread regarding B&W chromogenic film. Kodak used an orange mask, Ilford does not.

https://www.photrio.com/forum/threa...ms-is-there-a-difference.173119/#post-2252488

The only reason Kodak would use the mask was because the printing process (for color) expected to see it. The only dye coupler in a B&W chromogenic film is to produce a grey(ish) dye, so the orange cannot be a consequence of the color layers. I have stripped BW 400CN and the orange base looks exactly like any other Kodak C-41 film.

Even more to the point check out

https://www.photrio.com/forum/threa...and-white-chemicals.48578/page-2#post-2193776

Two comments of note:

- "If you use Caffenol the stain helps mask the orange and yellow masks."

- "I developed a roll of Kodak Gold 200...The orange mask was still there."

So C-41 film processed with NO COLOR DEVELOPER still has an orange mask.

As I have a curious nature, I dug out an old roll of Gold 200 (24 exposure!), took it into the darkroom, pulled the leader out about an inch (to get both exposed and unexposed emulsion) and blixed it. It came out uniformly orange. After washing in fairly hot (125F) water, I scraped the emulsion off. The mask came with it, so the mask is a dye in the emulsion. But is has nothing to with either the first developer or the color developer, and has nothing to do with the "adjacent dyes".

The orange mask is one of the single most important and mindblowingly brilliant inventions in the history of photography.
Without it colour photography would be much worse.

Slide owes its limitations and saturated colours partly to exactly the fact that it can't use the orange mask.

Watch this interview with the inventor, including the part where he tells the story of how he came up with the idea:

thuggins said:

So C-41 film processed with NO COLOR DEVELOPER still has an orange mask.

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Neither developing, bleaching, nor fixing has any appreciable affect on dye couplers, where no exposure has taken place, which, again, are there to form the dyes upon exposure and development. They are given the orange color when manufactured, therefore development is not needed to form their orange color. After development, residual dye couplers will form the mask that cancels the dye impurties that are present where dye is formed.

All this is due to the need to correct the dye impurities. They are there, and need correcting when an image is to be printed. In printing, the dyes are used twice (once in the negative and once in the paper) and the impurities will cause noticeable color degradation if not eliminated in the negative, which masking accomplishes. For obvious reasons masking cannot be done in the paper. Everything here applies to the motion picture industry as well. Movie color negative film is also masked to correct color when prints are made.

The orange color is not in a color negative because the paper "expects to see it". It is the other way around--the paper has a balance that, to an extent, accommodates the negative.

So, the paper that C-41 film is printed on is color balanced to take into consideration the presence of the orange cast of the negative. It makes sense that Kodak would have the b&w film with such a cast for easier printing but it appears minilab printers did not understand how to deal with it. Its mask could have been a simple uniform color, or act as a true mask in order to correct for dye impurities in the chromogenic image so the b&w image printed with correct b&w tonal values on to the color paper. Just guessing, I am not that familiar with that film type or its operation.

thuggins said:

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.

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gee giys, please read the atricle I linked above.

the MASK is part of the enulsion. It consists of "Coloured couplers" so yes, undeveloped but fixed film will look orange (unless it has the silver AHU layer, then without bleach it will look quite dark)

when developing - some of the colored couplers turn into real dyes. so they disappear in places where their is a colour spot of the appropriate colour developed. the end result is that the errors are corrected.

Please PLEASE Please read Brian Prichard's excellent, concise and simple to understand article... http://www.brianpritchard.com/why_colour_negative_is_orange.htm and lets be happy that this amazing bit of technology has allowed us to have Nice clear colours for the last 60 years. As one of my pals says "it's not Rocket Surgery"

thuggins said:

Rollei Digibase was an unmasked negative film intended for workflows that had no need for the mask.

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AKA aviphot 200. a film for mapping inteneded as a reversal film, but capable of being cross processed into an unmaked negative.

thuggins said:

It was originally sold as a slide film, but now marketed for cross processing, probably to increase the market.

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Some of that stuff I tried had a lovely yellow cast when processed as a slide, so the folks who bought out the supply suggested using it cross processed where the cast could be corrected. when fresh and in good condition, it was a similar emulsion to Agfachrome 200. but on a thin Polyester base.

thuggins said:

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

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Not since Kodak invented the mask.

RPC said:

. It makes sense that Kodak would have the b&w film with such a cast for easier printing .

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exactly. with c-41 B&W films where the intention was to print on a mini-lab have coloured couplers that he mini-lab will interpret as a colour negative. Ilford no doubt figured that their users would make convetional prints, and the organge colour make for difficult printing on regular blue sensitive B&W paper.

different assumptions about use.

just like any colour film manufacturer could sell "Uglycolor" colour film without the mask. just don't give the lomography folks the idea.

I remember making optical minilab prints from Ilford XP2 back in the early 1990's and the only way to get a half-decent print from it was to sandwich a piece of unexposed colour neg (yes the orange mask) with the neg.

Of course, this was before Frontier printers which digitally scanned the neg and then the orange mask didn't matter because you just selected a B&W mode (like PS desaturate) and it printed a B&W toned print on colour RA4 paper.

There was a mention above about making slides from (masked) color negatives. Kodak formerly made 35mm Vericolor Slide Film 5072 for just that purpose, and Vericolor Print Film 4111 in sheet sizes for larger transparencies. I used both of them extensively in a past life... both films were C-41 process, and discontinued c.2004. Beware, though, if you find any left; the film would fog to a cyan color after a few years, even when stored at 0 degrees F; so don't bother with it.

MarkS said:

There was a mention above about making slides from (masked) color negatives. Kodak formerly made 35mm Vericolor Slide Film 5072 for just that purpose,.

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yep, the only product left in that space is 2383/3383 for movies, and it will give high contrast from still negatives.