Dispelling myths in color processing

After reading this and other forums, I have found a lot of myths

presented as fact about color products and processes. I thought I

would list a few and dispel or affirm their truth AFAIK.

 

1. EK-RA chemistry cannot be used except at relatively high

temperatures. You must use a special kit.

 

Fact: EK-RA chemistry works down to 68 deg F (20 deg C) with only a

change in time and color balance needed to get a good print. I use 2

mins at 20 deg C.

 

2. You can use a BLIX (Bleach Fix) for C41 and E6 films.

 

Fact: You can, but you stand a very high chance of getting silver

retention. In fact, designing a blix for color films is one of the

most difficult solutions to design, and useful ones often can damage

film if time is too long, or they contain some nasty chemicals.

Sometimes shelf life is poor due to oxidation of the fixing agent(s).

 

3. You can use a ferricyanide bleach with modern color films, after

all the old color films used them. (or quinone or persulfate)

 

Fact: If you go directly into a ferricyanide bleach after the color

developer, you oxidize the color developer and cause an overall heavy

fog. You need a clearing bath and wash before going into a

ferricyanide bleach. In addition, modern couplers and dyes are not

routinely tested with these strong bleaches. Therefore, the couplers

or dyes may be harmed. Other bleaches recommended by the

manufacturers will work as long as the process cycle is modified

appropriately, such as using the clearing bath mentioned above.

 

4. Color fixes are basic.

 

Fact: Color fixes and bleaches tend to be slightly acidic, around pH

6 - 7, and are non hardening.

 

5. You can't mix color chemistry from scratch.

 

Fact: You can. It is not much harder than mixing some B&W

chemistry. But, you cannot do it economically, at least not with the

prices I have seen.

 

6. There are good published color formulas.

 

Fact: Every formula that I have seen published deviates

substantially from the actual EK formulas that I have personally

seen. (I have not seen all published formulas, but I have researched

a lot including patents) The missing or incorrect chemicals

generally tend to be those that affect microdensitometry (sharpness)

and granularity, and therefore you may get a pleasing picture with

the right speed, but not the right sharpness and grain as specified

by the manufacturer. In addition, these developers would tend

to 'season' improperly and therefore would only be useful in a one-

shot situation.

 

6. You cannot cross process C41 films in E6 processes.

 

Fact: Yes you can. You get a low contrast masked color transparency

that can be used for duplication purposes in certain cases. The

result is similar to a masked version of ECO film.

 

7. E6 films cross processed in C41 require heavy filtration for

printing.

 

Fact: Since any daylight film has a certain speed relationship, the

E6 film will print close to a C41 film in filter pack. The mask in

negative films is just a mask for color correction, not a filter. I

know what you are thinking, but it doesn't quite work out the way

logic would tell you, as the speeds of the negative film have been

adjusted for the mask in the first place. It all works out in the

end being pretty close.

 

8. Tungsten films are daylight films with a filter layer (or vice

versa).

 

Fact: Nope, daylight and tungsten films are different. They have

completely different speed relationships by means of using different

emulsions.

 

9. Freezing will preserve film almost indefinitely.

 

Fact: Freezing or refrigeration slows down all chemical changes in

unexposed or exposed film. This means that curve shape and speeds

among other properties remain close to when you bought the film. Fog

continues to rise due to cosmic or ambient radiation. Heat induced

fog is slowed down or stopped depending on temperature. This varies

from manufacturer to manufacturer and from film to film. Negative

films seem to survive better, because the fog can be 'printed

through'.

 

10. You can process Fuji, Agfa, and EK films together in the same

process.

 

Fact: Yes and No. All three families of films of either negative or

positive type use different chemistry to achieve the same end

result. Therefore, as a developer seasons in, it accumulates the

leached out chemistry of the most prevalent film being processed.

Each manufacturer balances their own films against each other because

they use similar chemistry. They cannot balance against the films of

other manufacturers due to the fact that the ratios of chemicals

change with the mix of film being processed. Therefore, you stand a

better chance with EK film using a facility that does mostly EK film

and Fuji in a Fuji facility, etc.

 

11. Fuji and Kodak negative films don't print on each others papers.

 

Fact: Kodak does not appear to print well on Fuji papers. Fuji

appears to be acceptable on EK papers. I know that EK tries to

maintain compatibility with Fuji and Agfa films, but it is sometimes

difficult (see 10 above), as there are other factors involved in

getting good prints across manufacturers products. Kodak has

published and uses the silver criterion for balancing color paper to

film, and by publishing this method, has tried to induce others to

follow the same methodology to achieve intercompatiblity. This

methodology does not limit the quality of color reproduction or tone

scale as some would think.

 

Thats about enough for now. I solicit your input to add to the list

or make objective, correct, and polite comments.

 

Ron Mowrey

12. Push/pull C-41, E-6 :-)

 

thanks Rowland, great contribution!

Ron; good list!<BR><BR>Re 9. Freezing will preserve film almost indefinitely<BR><BR>Here I have some films frozen from different eras; some from the lake 1960's. With some 120 roll films; I have found that the film develops a "mechanical set" after decades; and film flatness is worse abit; and sometimes the film is a devil to load on processing reels; compared to new films. The worse set was in some Ilford FP4 that I bought in the 1970's; and the same emulsion number; which got used at odd times; over a couple of decades. I got about 100 rolls for nothing when a store closed in the late 1970's; and had no trouble with it when new. With time; the film got a set/curl. <BR><BR>Sorry for the B&W aside; I thought some "film freezers" might want to know some extra dangers of old films.

la<b>t</b>e 1960's.

Exellent initiative, collecting all this information and killing some myths.

 

One thing: What does the stabilizer bath actually do? (please don't just say stabilize :) ) Does the formaldehyde "endcap" dyes, react with wasteproducts making them more hydrophilic? Make sure there is some formaldehyde present in the emulsion to kill eventual fungus/microorganisms that may thrive if film are kept under less than ideal conditions?

 

What happens if one skips the stabilizer in C41/E6 films? Is their archival properties compromized?

 

Stabilizer may also be used with paper, is skipping it altogether with prints a good/bad idea?

 

Hope you can elaborate Ron.

 

Thanks,

Anders

12 You can push / pull E6 and C41 films to get a higer / lower speed.

 

Fact: Yes and No. Pushing film raises fog. In negative films, the EI is therefore higher. Contrast goes up, raising EI. Toe contrast goes up so apparent ASA or ISO goes up. In reversal film, fog goes up lowering Dmax and thereby making mid tones lighter giving the appearance of higher speed. In my experience with negative films, about 15 seconds equals about 0.1 log E and about 5 - 10% in contrast. Professional films are more pushable. Pulling films lowers fog and decreases contrast somewhat. Threshold speed (ASA or ISO) go down.

 

13 Stabilizers stabilize film

 

Fact: Yes they do. They react with couplers just as a developer does chemically, preventing excess coupler from turning brownish, preventing excess coupler from reacting with dye and forming leuco dye, etc. In papers, stabilizers at one time provided proper pH buffering and an oxygen barrier layer for long term keeping. Film stabilizers should NOT be used with paper, and paper stabilizers should NOT be used with film. The newest paper stabilizers are only recommended for use if wash water is limited. The bulk of the paper stabilizers are in the paper itself.

 

As for old films keeping in the freezer. My oldest films are from the 80s, and most are still good. My biggest surprises were PPF2 just slightly out of date but frozen being very foggy but good in contrast and speed. And, Agfa XRS 1000 frozen changing in color balance by about 30 red. And developing a set is so severe in some old films, I have trouble getting them onto the reel for processing. I spent 45 mins with one old roll recently.

 

Thanks for the feedback.

 

Ron Mowrey

Re. '7. E6 films cross processed in C41 require heavy filtration for printing.'

 

In my experience this is not a myth. Most cross-processed E6 films are really hard to

print.

14. Color fixers are different / the same as B&W fixers.

 

Fact: I see people state this both ways. Some people say they are the same, some different. Some say color is more complex, some say simpler, some more concentrated, others more dilute. This is a big field. Color fixers are usually pH 6 - 7 solutions of Ammonium Hypo with ammonium sulfite added for stability and sometimes they contain accelerators to assist in silver removal. Remember, in color, one roll of film is about equal to 3 rolls of B&W because of 3 layers, plus you are removing every bit of silver (you hope). Also, that silver is restrained by heavy doses of DIR coupler residues and other image enhanching chemicals. So.. you take a guess. Which is more complex? Color fixers are a bit more complex. A simple fix will work, but you have to leave the film in the fix about 2x longer to remove the silver halide. AND.. all color fixers are unhardened. So never use a hardened fixer or a strongly acid or basic fixer on color films unless you like to ruin your images or at least seriously disturb them.

 

15. Kodak had a C21, C42, E5, E7 etc, process.

 

Fact: E5 is the only real process above. It was used for Aerial Ektacrhome in a motorized reel to reel processor used in the field and in a roller transport processor. It was virtually identical to E4. The others never existed. Only two other processes were seriously considered during my knowlege of processes at EK, and they never saw the light of day much less got a process number. Their consideration lasted for a short time and they were abandoned. There were many valid film and paper processes not mentioned above such as E1, E2, E3, E4, P122, K14 and etc. These are well known in the literature.

 

I'll keep adding as my researches unover more data.

 

Ron Mowrey

Elliot, do you mean hard to print for machine/custom/ or yourself? What stocks are you using?

Eliot;

 

I didn't say they were not hard to print. They are hard to print due to the high contrast. And so..

 

16. Contrast has no effect on printing color slides / negatives

 

Fact: Yes it does. Color negative papers, with an average contrast of 2.5, matched with a negative film of 0.6 average contrast moves at 2x the apparent rate of color shift than a color reversal paper with a contrast of 1.0 and a film of 1.7. You need a bigger filter change to see the same visual effect when printing slides than when printing negatives. Back in the days when slide printing from Ektachrome paper was very popular, EK published a special note on this effect and cautioned photographers about it.

 

If you have cross processed Ektachrome as a negative, a very tiny filter change may make a huge shift in balance. In addition, any crossover further confuses the issue. However, the starting filter pack of Ektachrome cross processed should be close to if not the same as your starting pack for average negative films.

 

Which brings up:

 

17. Prints from slides are equal to or better than prints from negatives.

 

Fact: They appear very sharp due to high contrast, and the color saturation is high but.. Color accuracy cannot equal a negative unless you use a color mask, and contrast will always be too high unless you use a contrast mask. Color negative film is designed for making prints and only making prints, either on reflection or transmission support. The curve of the original is multiplied by the curve of the print material during the printing process, and due to the toe in a transparency and the toe of the print paper, you compress highlight and shadow detail. A negative film with a long straight line curve only has the toe and shoulder of the print material to contend with and therefore will always have 1/2 of the tone compression or detail loss of a print from a transparency. I am grossly simplifying the calculus involved in this transaction.

 

18. Plotting an H&D curve of a film will give you an idea of its contrast in-camera compared to another film.

 

Fact: It will not. It is one method used to test a film for speed and contrast on a macro scale. Due to edge effects in ALL films, color and B&W, the micro contrast is usually different than the macro contrast. In addition, the contrast of a single color exposure in color films is ALWAYS different than the neutral exposure and is a more correct representation of the color saturation of the image.

 

This should have been #1, I think after re-reading some of the posts here.

 

Ron Mowrey

Ron,

 

<B></B><BR>         Geez, you haven't left us much to argue about anymore. ;) Re No. 12 above. I assume you are talking about push processing. Some people say that the C-41 process is development to completion; further time in the developer does nothing to increase the density of the negative. Fact or fiction?

Ron,

 

Your #9 about freezing film probably deserves some elaboration since any generalization which concludes that all films can be kept indefinitely by freezing them is wrong. All films are subject to actinic (background)radiation, and its effect is proportional to film speed. The problem that results is not just fog as you suggest; rather it is significantly increased granularity. This cannot be printed out. This issue is discussed by Kodak in http://www.kodak.com/global/en/service/tib/tib5201.shtml#SEC45

 

Thermal degradation of modern films is a comparatively minor issue. In other words, freezing film prior to exposure is an overrated panacea -- especially for higher speed films.

Fiction.

 

C41 films still have a ways to go when pushed. Threshold speed appears to go up due to increased toe contrast, and mid scale contrast and therefore EI goes up as well. As you push harder and harder, you truncate the long straight portion of the curve and accentuate or lengthen the shoulder, but that is about 2 stops push or probably higher. I have not done that high a push for a few years.

 

With the appropriate exposure and push, I have gotten over 1200 out of a 400 film with good results. Grainy, high contrast, but good image. One image set was done at 2400. Very short latitude, and very grainy, but the image was usable. Thats better than nothing. Right?

 

AFAIK, E6 is a process to completion after the MQ. The fog in the MQ step controls push. RA paper is a process to completion. It is very hard to overdevelop Endura. Supra II was easy to overdo, but Supra III solved that problem pretty much.

 

Which brings up:

 

19. Film has no speed limit / has a speed limit. Digital has no speed limit / has a speed limit.. etc.. ad nauseum.

 

Fact: There is a theoretical speed limit to film due to radiation and heat effects. A film of about 20,000 would be possible, but would fog very rapidly due to the above effects. It wouldn't go through airport security stations worth a darn. Digital images suffer from thermal 'dark noise' effects unless cooled in the camera. Until the heat generated by digital sensors is decreased, they may suffer speed limitations due to the heat that they generate themselves. Pushing film or digital increases noise (grain) and compresses tone scale.

 

Ron Mowrey

First: Thank you, Rowland. It's a blessing to have accessible on this forum people with expertise gained through study, on-the-job experience or careful empirical work in their own darkroom. Although I was a chemistry major, I can only guess what are the important minutiae of color processing.

 

I have a question as I contemplate developing in a Jobo several rolls of 120 Fuji NPH and 35mm Kodak Max. Would it be better to use a Tetenal Press-Kit or Kodak Flexicrome developer followed by Tetenal or Peterson bleach-fix. I'd rather not go Kodak all the way as their C-41 uses separate bleach and fix and I'm thrifty and lazy.

 

Also, you refer to ECO film. What is it?

 

Thanks,

 

Bob W

Joe;

 

Thanks for the added information. Of course, no film keeps forever. Cooling it still helps freezing helps more. Even the newest films fog slowly due to radiation. That was my bad.

 

Nice hearing from you.

 

Ron Mowrey

Robert;

 

Than you for the nice comment.

 

Under your conditions, mixing those films probably will cause no problem whatsoever.

 

I have no experience with the Tetenal developer. The last time I tried the tail ends of any of those processes, I had trouble with silver retention so I abandoned them. Short of testing them myself, I wouldn't care to comment one way or another except on the silver problem.

 

Several other individuals have commented on those kits. I urge you to look it up in the archives.

 

ECO was a low contrast reversal motion picture film intended for printing. It was about 1.0 or less in contrast with a long tone scale and used a special print film to get distribution prints. It never caught on, because as one of my notes above states, prints from transparencies are not as good as prints from negatives.

 

It could be used though to give some striking duplicate slides.

 

Ron Mowrey

Thanks for a great thread, Ron. Please clarify a few more myths and questions for an amateur.

 

Should one use expired slide film? How do they degradate after the expiration? Are the expiration dates on the conservative side?

 

What makes professional film special? How should professional film be used to get the best results, i.e. stored, shot within a time frame, and processed by a pro lab?

 

TIA.

'Elliot, do you mean hard to print for machine/custom/ or yourself? What stocks are

you using?'

 

I was talking about hand-printing on Kodak and Fuji papers. In my experience cross-

processed films do require radically different filter packs from conventional films.

Finding the right filter pack takes time, and this is why I said that printing cross-

processed films is difficult.

 

(Printing cross-processed Provia 100, for example, will often require the use of the

cyan channel.)

 

Sure, some cross-processed films need less extreme filter packs - but not all.

I've always found the Fuji films harder to print Elliot, Velvia being the worst. Agfa RSX II 100 is easy and has just the little subtleties of a crossed image while maintaining nice skin tones and contrast.

Yes, last time I printed Agfa RSXII 100, it required just a small adjustment to the filter

pack I was using for Portra 400 (an extra 30M and 15Y).

Having not printed RA-4 myself or developed color film, I haven't researched the area and this amount of misinformation struck me as a bit surprising and a bit funny. However, I must say that discussing computer/software issues tends to be even more technically innacurate here on photo.net, so this is really no that surprising.

 

How about editing this thread and HTMLizing it all for a conveniently accessable web page? I can volunteer for the editing and HTMLizing if you like...

 

Oh, and thanks for the info, I've tried my first cross processed roll (EPJ in C41) recently and I'm intrigued about the properties of the resulting negative.

Oskar, I've also noticed the lack of a good site about color processing, and would be happy to help. I was thinking APUG.org might be the right place - they're set up to host How To articles, for instance.

Answers to some questions:

 

1. I have heard, but not tested this out, that Fuji films cross process more poorly than EK films in C41. I do a lot of Ektachrome in E6 and in C41. I too enjoy the results of the cross process film when printed, and I am able to print them with virtually no change in filter pack depending on reversal film type.

 

2. Expiration dates are a best guess using averaging of keeping conditions and tend to be conservative. That does not give you a big window though. You don't know how long ago film was manufactured and how long it was on the dealers shelf. Reversal films fog and change in speed at room temperature. Contrast also changes. Negative films do the same. The difference is that you can often print out the changes in negative films which have expired, more easily than you would expect, but the changes in slide films becomes intolerable after just a short time. And, you can't fix the image on a slide film once it is bad.

 

This leads me to add:

 

20. Professional vs Consumer films, wow what a mess. People say they are the same others say they are different, others say they are selected etc.. etc...

 

Fact: Professional and consumer films from EK are different products, not selected cuts from a master roll, and not specially aged versions of consumer product. First, as EK states on their web site, professional films are more pushable, especially the press variety. This is due to the fact that pros generally expect to run into situations where they need to have this capability. Second, the pro is expected to want fresh film, but may keep it outdoors on a Safari in Africa, so it is expected to be refrigerated until use, but then used under adverse conditions. Latent image keeping is not expected to be a problem. No pro would let the film sit for 10 years in a dresser drawer. And lastly, pros expect their film to be the most stable in color balance from batch to batch. Therefore, the pro film is, to my mind, a more robust, stable film up until use, with more processing latitude. After use, it should be recooled as needed and then processed promptly. This means that professional and press (I put them in the same category), and consumer are two families of film products with different properties tailored to the intended market. They may and probably do contain many of the same chemicals, and emulsions, but their proportions in the films are adjusted to achieve the desired properties. This does not appear to be so for Fuji films. According to their web site, professional films are a special cut of film from a master roll to insure uniformity. Now, you can interpret this following comment any way you want, but I believe that if EK had that kind of uniformity problem with coating, the master roll would be scrap. EK expects uniformity from side to side and end to end in a master roll. There may be enough variation in a master roll to give parts of it a different emulsion number due to a slight color balance shift for example, but if it was a professional coating all of it would be good enough for professional use.

 

Thanks for the good feedback. If you find errors or have more myths to add, please post them.

 

Ron Mowrey

Oscar, Peter;

 

How about a chat room as an SIG on AIM. I use this regularly to chat with SIGs. You might want to consider it. It is easy to set up and is convenient. It takes on a life of its own. It costs nothing, and the sessions can be saved locally. You can send photos, and even talk as if you were on a telephone connection.

 

I'm usually on AIM from 3 - 11 EDT. "tabini aiji ma"

 

Regards.

 

Ron Mowrey

These should be on a single web page in the "Learn" section.