C-41 colour film and the orange mask

[pellicle]

Hi

perhaps my brain is only ticking over slowly, but I was wondering if I've got this (should be simple) concept straight.

The "orange mask" in C-41 negative is not a uniform density filter, but is a mask which is dependent on density (exposure?)

does this mean that C-41 colour negative film is effectively pre contrast-masked?

thanks

 

[AgX]

No.

Integral Masking (which is employed in the vast majority of C-41 films) is not aimed at controlling overall contrast but to control unwanted absorbtions of the dyes resulting from coupling.



In detail:

The idea behind Integral Masking is that opposing to the the image density resulting from unwanted transmission of a dye an image density of the same colour but reciprocal density is built up. Thus resulting of a small overall density of that colour which is nothing more than colour shift.

Instead of getting rid of the unwanted density of the resulting dye the coupler is modified in a way that its absorbtion is alike the unwated absorbtion of dye, but will loose that after coupling.
For example, a coupler leading to magenta but also to a slight yellow hue is modified so that itself is no longer colourless but has a slight yellow hue. After coupling magenta will be formed, but those uncoupled couplers in the unexposed areas will still have their yellow hue, compensating for the unwanted yellow hue in the exposed areas.

In general slightly yellow and slightly red coloured couplers are employed.

One could call this approach horizontal as the opposing action comes from within the same layer.

Another approach works via the adjacent layers and is called Vertical Inhibition. Here the unwanted density is controlled by reducing densitiy of that colour in the adjacent layers.

In this concept all couplers are colourless but hold a inhibiting group. This is released after coupling and not only controls further development in their own layers but in the adjacent layers too. By that they are able to reduce the primary density in the adjacing layers, thus compensating for their unwanted density in their own layer. The disadvantage of this concept is that it needs primary densities in the adjacent layers to function.

Both concepts can be employed in one film.

Vertical Inhibition is used in Agfa’s current maskless C-41 films.

 

[pellicle]

Agx

thanks for going into detail. For some reason I had a memory from about a year ago of (I thought it was) photo engineer saying something like " its a mask not a filter" which I appear to not be able to find. Clearly my memory fails me here.

What you say makes sence as I have used unexposed leader (of 120 film) to 'mask' my scanners light calibration area to attempt to obtain better colour penetration. I don't think my results indicated more than could be done in software (indicating that perhaps the calibration is also just software at a different point) rather than adjustment of analog gain or anything beneficial like that.

In detail:

The idea behind Integral Masking is that opposing to the the image density resulting from unwanted transmission of a dye an image density of the same colour but reciprocal density is built up. Thus resulting of a small overall density of that colour which is nothing more than colour shift.
...
Vertical Inhibition is used in Agfa’s current maskless C-41 films.

Thanks for the oblique suggestion of the Agfa maskless C-41 film, I'm thinking of trying that film to see if it has benefits in my scanning. Perhaps it will assist in getting better access to blue with my (Epson flatbed) scanner.

 

[pentaxuser]

Vertical Inhibition is used in Agfa’s current maskless C-41 films.

What are the current Agfa C-41 films called? I can only recall Agfa Vista C-41 films here in the U.K. and I understand these have been discontinued. I haven't seen any stockist with Agfa C-41 for a long time.

Are they available in the U.K.? Maybe UK APUGers can ptich in here as well.

Thanks

pentaxuser

 

[Photo Engineer]

Its a mask, not a filter. I repeated it just for you here.

Kodak uses 6 methods in C-41 films to improve image color, sharpness and grain.

1. Masking as described above.
2. Interlayer effects where one layer changes the development in another layer (DIAR couplers)
3. Intralayer effects where a layer changes its own internal development and image structure (DIR couplers)
4. Interlayer / Intralayer effects (Iodide, DIR and DIAR effects due to development)
5. Scavengers to improve sharpness and reduce color contamination
6. Acutance dyes to mprove sharpness.

E6 films cannot use most of the above at all or cannot use them as effectively, because the color development must go to completion and because the first developer is only B&W.

PE

 

[AgX]

pentuxuser,

Remember that Agfa has retracted from the `consumer imaging´ business in the fall of 2004.

The current Agfa C-41 films are:

Aviphot Color N400
Aviphot Color N800
Aviphot Color X100
Aviphot Color X400

(The two `X´-films are the maskless ones.)

As you see these are all out of their aero-film portfolio and thus converted to those sizes.
However the Aviphot X400 is also offered as 35mm DP as Agfa ASP 400X.

The Aviphot X400 also seems to be identical to Maco’s Rollei Digibase CN 200.

 

[pellicle]

Photo Engineer

Its a mask, not a filter. I repeated it just for you here.

thankyou Its nice to have some positive support that (in my aging process) that not everything is dying as fast as it feels like it is.

ability to recall those details from 20 years ago ... ability to see the things closely without resorting to accessory lenses ..

sigh ... why after 40 do these things fade away.


anyway ... it appears that I do not grasp the difference between a mask and a filter correctly. Mask brings up so many things in my mind:

• contrast control
• concealment of things (borders and cropping when printing)
• and perhaps I spent too much time in IT as well (bit masks)

is the mask uniform?

E6 films cannot use most of the above at all or cannot use them as effectively, because the color development must go to completion and because the first developer is only B&W.
PE

so is it fair to interpret from this that colour negative films are therefore greater able to record colour better than positive films? (say avoid things such as metamerism or some other issues)

 

[AgX]

...so is it fair to interpret from this that colour negative films are therefore greater able to record colour better than positive films? (say avoid things such as metamerism or some other issues)

Metamerism is (to my understanding) the change of colour impression between two objects when the spectral characteristics of light changes. But perhaps you are refering to the difference in colour reproduction of a single subject when photographed with different films. A well known example is the reproduction of certain violet-blue blossoms which turn out magenta due to their IR reflection and being photographed with a colour film being sensitized up into the IR.

In the late nineties or so there was a general habit amongst manufacturers to modify the spectral sensitivity of the red sensitizer giving it a peak at about 650nm and a steeper fall-down to red side.

But these all are issues related to the sensitization of a colour film.



Masking and the other means referred to above are aimed at keeping those information taken up by the sensitizers as pure as possible through the dye-forming process.

 

[pellicle]

Hi again Agx

thanks again for your inputs

Metamerism is (to my understanding) the change of colour impression between two objects when the spectral characteristics of light changes.

I was thinking something similar, that two things of dissimilar colour could appear to be the same colour dependent on the frequency mix of light illuminating it.

I basically understand that the issues of how the trichromatic colour model corresponds to physiology of our vision, but occasionally things like metamerism make me feel that my mental model breaks down. Like if we illuminate white card with the three primary colours (RGB) it will appear white even though there are significant 'notches' in the spectrum. If just a few are missing (from full spectra white) we may also see it as white, but something of a colour (uneven reflective spectral responce) may appear differently.

gosh this stuff is confusing ... no wonder I like black and white the most ;-)

 

[Photo Engineer]

A filter is uniform in density but a color mask has varying density that is inversely proportional to the image.

Metamerism can take place as AgX has defined it and as you define it. It can go either way, is my understanding.

PE

 

[pellicle]

PE

As always ... thank you

It isn't always easy or obvious understanding how all this works. I look upon colour film as being quite a pinnacle of achievement in (chemical / physical) technology depending on many (relatively speaking) recent discoveries and understandings. The system is quite good (for its perhaps compromises).

As someone who did not obtain classical education in photographic technology (that's been in Biochem & Information Technology) the results of being self educated are often a bit hit and miss.

 

[AgX]

Concerning filmmaking itself, there is no `classical education´ I guess.

Some basic ideas had been given at the few schools who taught photo engineering, some are referred to at chemical schools in case the lecturer has a tie towards photography.

In any case there is no complete textbook, nor public lecture on that matter. One has to learn at the few manufacturers or collect those morsels publicly accessible.

So you are not on your own with that hit and miss thing.

 

[Photo Engineer]

And this is the very reason I have said that when film making is gone, it is gone - as we know it. Particularly color.

PE

 

[Mr Bill]

Pellicle, I believe I once suggested to you Hunt's book, The Reproduction of Colour. Let me now be more emphatic. I think this is the book you need to see. Granted, it's not for everyone, people learn in different ways. But I have a feeling that it's exactly right for you.

http://www.amazon.com/Reproduction-Colour-Imaging-Science-Technology/dp/0470024259

Below is the first paragraph out of several pages explaining the principles, so you can get a feel for the tone of the book.

15.4 Coloured couplers
The black-and-white masks used in the old Kodacolor film enabled the saturation of colours to be increased by raising the contrast of the system without spoiling the tone reproduction, with some corrections for the unwanted absorptions of the magenta and cyan dyes. However, a more elegant method of correcting for these unwanted absorptions was introduced in 1949 (1948 in the case of Ektacolor film, for professional use): the colour-forming couplers were themselves coloured, and in such a way that, as dye was formed, the transmission of light in the regions of unwanted absorption remained constant. The negatives now become orange in the unexposed areas. (See figure 12.8). The use of these coloured couplers in colour negative films is very extensive, and the principles involved will now be described.

 

[pellicle]

Hi

Concerning filmmaking itself, there is no `classical education´ I guess.

...

In any case there is no complete textbook, nor public lecture on that matter. One has to learn at the few manufacturers or collect those morsels publicly accessible.

And this is the very reason I have said that when film making is gone, it is gone - as we know it. Particularly color.

a very interesting pair of quotes. As someone who is (more or less) into the academic information dissemination philosophy (and at loggerheads a little with internal corporate knowledge) its interesting to see another example of the potentials for knowledge loss to mankind through corporatisation. I guess that its a hard line to tread, patents protecting business investments VS free exchange of information.

perhaps through forums like this (and their archiving) someone in the future can mine this information

 

[pellicle]

Mr Bill

Pellicle, I believe I once suggested to you Hunt's book, The Reproduction of Colour.

yes, and I have not forgotten it ... but presently my circumstances are that I'm living in Finland and trying not to aquire more stuff to move back to Australia with than I have to ... but I will be getting it in the (I hope) near future.

 

[Photo Engineer]

The book by Evans, Hanson and Brewer is better. It is "Principles of Color Photography". One of the primary inventors, W. T. Hanson is an author, and the book is rather a bit more eloquent than Hunt's work.

Also, compare the prices: http://www.amazon.com/s/ref=nb_ss_?url=search-alias=aps&field-keywords=Evans,+Hanson+and+Brewer

PE

 

[Mr Bill]

...I'm living in Finland and trying not to aquire more stuff...

ahhh... I actually had libraries in mind, but it suddenly occurs to me that that a book written in English is unlikely to show up where you're at. The book is expensive enough that I'd suggest have a good look before you buy.

I can't argue over which book is best, since I've never seen Hanson's (the thought never occurred to me that he may have written a book, thanks PE). I will say, though, that I eventually bought Hunt's book because I wanted info not in my library's earlier edition. Certainly, though, Hunt's prose is a bit dry, and does not lend itself to pleasure reading. Yet, when I look to gain an understanding, I can get it quickly from his very concise explanations.

 

[ericdan]

And this is the very reason I have said that when film making is gone, it is gone - as we know it. Particularly color.

PE

Well, somehow FujiFilm, Kodak, Ferrania and Agfa all came up with similar results independently. I assume they weren't sharing methods.

 

[Photo Engineer]

They did use the same methods. They cross licensed patents or by analysis used undisclosed trade secrets. Or, they waited until the patent expired before using a method.

PE

 

[flavio81]

They did use the same methods. They cross licensed patents or by analysis used undisclosed trade secrets. Or, they waited until the patent expired before using a method.

PE

One of the most interesting comments i've found on APUG.

Now, regarding this comment by PE:

I have said that when film making is gone, it is gone - as we know it. Particularly color.

I am not sure if I understand correctly that statement -- because Kodak is still making color negative film; Fuji is still making color reversal AND negative film, and most of the Agfa equipment for making it plus the engineers are at InovisCoat.

Also, keeping things in perspective, it is year 2016 and it was only 6 years ago since a brand new, state-of-the-art color film was introduced:

LONDON, UK, Sept. 14, 2010 – Eastman Kodak Company (NYSE:EK) today introduced the new KODAK PROFESSIONAL PORTRA 400 Film, featuring the finest grain structure available in a 400 speed colour negative film.

I can understand that most likely, zero research and development on color films has been done since 2010.

However, only six years have passed! That's nothing. And we know why the demand of film fell - because consumers went to digital photography changing forever the way consumers take pictures. But at the same time even the market for digital cameras is now facing tremendous problems. While the analog photography market has now settled down into small but stable dimensions.

So, even if the state of the art in color film technology is not advanced further than 2010-state-of-the-art, i see no reason to think color films are going to dissappear, even less considering that the Ferrania efforts are still persistent even though they faced lots of unexpected problems.

As for the technology being proprietary, yes; the technology is proprietary but the companies are still there and the engineers are alive, and they can be hired as needed. And if this stable demand for color film persists, then the knowledge for making it will persist.

Let's suppose that theoretical company "FUJIDAKFA" is making color film in a profitable, sustainable way, and inside FUJIDAKFA there is a highly respected and knowledgeable engineer, say, 72 years old, "master yoda" of color film making - for this example let's call him "Edwin H. Rowland" or "Rochester Ron", then the natural consequence is that some young, talented engineer, will also learn from Rochester Ron within the company and, decades later, be the next "master yoda" of color film making.

Furthermore, i guess INSTANT color film is much more difficult to engineer and manufacture than color negative or positive film -it took a giant like Polaroid years (from 1963 to 1972) to be able to tranform their new color instant film into an integral film type, inventing a lot of new things in the process. I've read somewhere than when such an integral color instant film is developed, over 1000 (one thousand) chemical reactions take place.

So if instant color film is still being manufactured (by the Impossible project), setting aside the quality of such recent film, why can't color film be continued to be engineered and manufactured, in a more reasonable scale, in the years to come? Is it for business reasons? I don't see the industry dying; i only see the industry reducing to a smaller scale. Also, nowadays that (for example) medium format cameras are affordable, and that pro photographers have moved to digital, a film that has higher grain than the state-of-the-art, or a film that has not as accurate colors as the state-of-the-art, but is reasonably priced, will be perfectly commercial and successful in 2016, 2017 and the years to come. While such film would have flopped in the 1990s against Kodak and Fuji offerings.

Also, don't discount Fujifilm. Kodak has had a textbook example of bad management for decades, and Fuji's professional film division is currently winning world-class awards on how to alienate your consumers, BUT, HOWEVER...

... that doesn't mean that in a few years a new management at Fujifilm decides a change of direction for the best regarding color film!

Etc etc.

I would really like your opinon on this, Photo Engineer.

 

[flavio81]

PS: I compare this to vinyl record cutting and pressing. The record pressing business went really to a downhill 10 or even 20 years ago, because consumers went first to CDs and then to MP3 players and then to music downloads.

However, nowadays, the vinyl record industry is thriving, it has grown steadily in the last 5 or 8 years, and ALL the record pressing plants are currently working at full capacity. The cutting engineers are working happily, etc. The machines that were abandoned or sold as scrap years ago are now restored and being used.

I can envision the same for the film business. I know making film is much, much, much harder; but what I mean is that commercially i can't see film, color film, dying.

I can see it dyeing, though.

 

[Prof_Pixel]

However, nowadays, the vinyl record industry is thriving, it has grown steadily in the last 5 or 8 years, and ALL the record pressing plants are currently working at full capacity. The cutting engineers are working happily, etc. The machines that were abandoned or sold as scrap years ago are now restored and being used.

I can envision the same for the film business. I know making film is much, much, much harder; but what I mean is that commercially i can't see film, color film, dying.

Ron's comment was : "I have said that when film making is gone, it is gone - as we know it. Particularly color." The point being that because of the mechanical technology and chemical technology needed to make film, once it's no longer being made (if that actually happens sometime in the future), it's very unlikely that it could be restarted again. Making film (particularly color film) is far more complex (it involves a lot more than just emulsion making) than making vinyl records.

 

[flavio81]

Ron's comment was : "I have said that when film making is gone, it is gone - as we know it. Particularly color." The point being that because of the mechanical technology and chemical technology needed to make film, once it's no longer being made (if that actually happens sometime in the future), it's very unlikely that it could be restarted again. Making film (particularly color film) is far more complex (it involves a lot more than just emulsion making) than making vinyl records.

Thanks Professor, for the clarification.

I contend that i don't see color film making going 'out' in the future, in my post above.

And on the other hand, i am no chemist but I have a friend, chemist, that is specialized on computational chemistry and he raves about the speed of new developments on the topic. I can't help but feel that in year 2026, engineering a decent color film will be feasible even if color film making stops in 2016. It might become easier in the same way that optimizing a 50/1.4 lens was extremely difficult in 1955, and easy in 1968, due to advances in computer simulation.

 

[Photo Engineer]

Flavio, Fred is correct though in his post above. Color film is a very complex thing. Just see how long it is taking Ferrania to get a coating line going when they have literally everything, including equipment, engineers, buildings, chemicals and money. Imagine having none of those. That will be the situation at some unimaginable time in the future. No film. No chemistry. No engineers. No money - who would care then?

PE