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Editor’s Note: Thank to the photo.net members who were kind enough to lend their color film images for this article. Be a pal and go check out their portfolios when you are finished reading the article. -Josh
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.
Fact: Eastman-Kodak-RA chemistry works down to 68? F (20? C) with only a change in time and color balance needed to get a good print. I use 2 minutes at 20? C.
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).
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.
Fact: Color fixes and bleaches tend to be slightly acidic, around pH 6 – 7, and are non hardening.
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.
Fact: Every formula that I have seen published deviates substantially from the actual Eastman-Kodak 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.
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 Eastman-Kodak film using a facility that does mostly Eastman-Kodak film and Fuji in a Fuji facility, etc.
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.
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.
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.
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.
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 enhancing 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.
Fact: E5 is the only real process above. It was used for Aerial Ektachrome in a motorized reel to reel processor used in the field and in a roller transport processor. It was virtually identical to E4. E5 is actually similar to E3, in that it has no prehardener. E4 had a prehardener and ran at 85? F, E3 ran at 75? F, and E5 ran at 70? F. The others never existed. Only two other processes were seriously considered during my knowledge of processes at Eastman-Kodak, 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.
Process EA-5 has been replaced by Process AR-5. The aero films now include hardener. Process AR-5 uses EA-5 chemicals except for the prehardener and neutralizer.
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.
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. However, see also myth 17.
Fact: Nope, daylight and tungsten films are different. They have completely different speed relationships by means of using different emulsions.
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 virtually 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’. In practice, though, no film keeps forever.
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. Developing a set is so severe in some old films that I have trouble getting them onto the reel for processing; I spent 45 minutes with one old roll recently.
Fact: Kodak does not appear to print well on Fuji papers. Fuji appears to be acceptable on Eastman-Kodak papers. I know that Eastman-Kodak 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.
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, Eastman-Kodak 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.
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.
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.
Fact: Professional and consumer films from Eastman-Kodak are different products, not selected cuts from a master roll, and not specially aged versions of consumer product. First, as Eastman-Kodak 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 re-cooled 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 Eastman-Kodak had that kind of uniformity problem with coating, the master roll would be scrap. Eastman-Kodak 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.
Fact: Color processing at home is easy. You have one time and temperature you can stick with for all films, unlike B&W, and you can be assured of hitting things right on if you do things the same way every time. Color is more expensive, but rather economical if you do enough to keep the solutions from going to waste. If you let them sit too long, and they spoil, then it gets expensive. So, keep your temperature, times and agitation constant and you can’t go wrong.
Fact: They keep at least as long as B&W. Bleaches, fixes and stabilizers actually keep longer; I have had C41 bleach and stabilizer keep for over 2 years in closed containers with occasional use. The only ones to worry about are the developers and the blixes. Blixes sulfurize rapidly even in closed containers. My record for keeping developers is about 6 months for RA. IMHO, the best plastic containers (most oxygen impermeable) are JOBO 1, 2 and 5 L bottles. They are superb but expensive. I have 4 different kinds of bottles, and the JOBO always performs best for keeping developers. I have a nitrogen tank to use if necessary, but even without nitrogen, I got that 6 month or so keeping with the RA developer in a 2/3 full container. I got that good keeping before I installed the nitrogen tank, so I figure I can get a 1 year keeping on developers now. I mix my blix just before use and expect about 1 – 2 weeks keeping. Blix unmixed keeps for up to several years as a two part concentrate. Developer concentrates probably keep about two years. I have had developer go bad if the developing agent concentrate is in plastic containers – sometimes within a year. If in glass, I have kept the concentrate for about 5 years and it still is good.
If you wonder how or why I have kept some of these so long, well, I usually buy 2 – 4 1 gal or 10 L kits at a time and put them aside to use as needed. Depending on darkroom activity, I may use them up in a year, or it may take me 2 – 3 years for some kits. I go through an E6 kit less rapidly than C41 and go through C41 less rapidly than RA.
Fact: My darkroom varies from 18? C in winter to about 30? C in summer. If I have an open box of paper, I leave it out. I find no significant problems over a period of about 1 year keeping with the following caveats: a) Supra I lost red speed and became reddish over 1 year. Correction with color filters (about 20R in one year) fixed the problem. There was no significant fog or curve shape change. b) Supra II was foggy if overdeveloped and was slightly more sensitive to that problem (I think, I don’t have enough data) if kept at room temperature. c) Endura is too new for me to evaluate, but at 6 months looks good. d) the Supra III I have has been on the shelf at room temperature for nearly 1.5 years now and is just showing a bit of red shift, about 0.10 if any. No fog increase yet and no apparent curve shape change. So, it changes, but slowly and the changes can be compensated for over one year with CC filter changes. It does not spoil, per se. Of them all, Supra I and Supra II were the most sensitive and they were still usable even so. Take this one for what it is worth. Just personal darkroom practice and experience. As a side note Ektacolor 70 kept rather poorly at room temperature. Ektacolor 20 was even worse. They lost speed, gained in Dmin and got softer in the toe over about 1 year.
Fact: Yes and No. Color developers are inherently B&W developers with a different developing agent. These color developing agents are selected for low toxicity and are about on the same level of hazard as HQ or Metol. Blixes are Ferric EDTA, Ammonia and hypo. This is not bad, in dilute form (about 1:10 parts water) for putting on your oak trees and rhododendron plants – about like MIRACID or MiracleGro without the acid. The E6 reversal bath contains Stannous Chloride, and the tin in it is not very good. The stabilizers for film contain formalin which is toxic and nasty. So, the real bad actors are the stabilizer and the reversal bath. Now, lets compare that to a B&W selenium toner. Nasty stuff. The toxicity level of the toner and the stabilizer can’t be compared. The selenium is probably an order of magnitude more toxic than the formalin. IDK for sure. I wouldn’t drink either one or put either on my flower bed. The color paper process is rather benign by comparison. Color developer and blix. About the same for a B&W film or paper. If you run any of this down the drain, what can you expect. Well, basically the BOD and COD are high for color solutions (Biological Oxygen Demand and Chemical Oxygen Demand). This means that color solutions deplete oxygen in the water and suffocate organisms. But, the COD is lower if you mix the blix or bleach with the developer. So, color processing solutions have a BOD like B&W and a lower COD than B&W if the developer and blix are mixed and dumped.
Where does all of this get us? Conventional Color processing solutions are about as toxic as B&W solutions. The stabilizer in color processes, and the reversal bath are similar to working with the more toxic of the toners such as selenium, but not quite on that level. The COD is lower, and the BOD is about the same as B&W.
Lets go to Ilfochrome. It is basically a B&W process with a VERY acid bleach. If you neutralize it, then all you have left is a solution of organic chemicals similar to a B&W process with two additions. These are the fragments of the dyes bleached in the process, and the catalytic bleach agent. These are anilines and a phenazine derivative. They are carcinogens, but in very low concentration and probably selected to be of the lowest possible toxicity.
Now digital. First, the manufacture of sensors requires doping with arsenic and selenium among other chemicals. The manufacture of computer chips and memory chips are the same and the video monitors use lead. The phosphors on the screens are toxic heavy metal compounds in some cases. The inks used in color printing are azo dyes and are somewhat toxic.
Now film making – color and B&W. These are mature industries that have worked for 40 years to eliminate all heavy metals and toxic effluent. There is no longer cadmium and mercury used in making film, nor is formaldehyde used. Methylene chloride is used in making the support, and a lot of the coupler synthesis is about as toxic as making the Ilfochrome azo dyes or the digital azo dyes, so film making is not an extreme environmental hazard.
In the end, to summarize, photography overall offers a reasonably safe working environment if precautions are taken such as ventilation and rubber gloves. Dumping into the sewer system is probably ok for the home hobbyist because the levels of chemicals is so low. The film stabilizers, E6 reversal bath, and selenium and other toners are to be watched out for and handled with caution, but except for the selenium are not severely toxic and don’t present any special hazard other than as noted. It is probably more toxic to dump a computer in a landfill than to dump a years worth of your photographic solutions into the sewer system IMHO.
One last note. I have read recently that pyrogallol is very toxic. I want to warn you of that. Another warning is that you should avoid putting too much acid in fix baths as it can generate two toxic gases, SO2 (sulfur dioxide) and H2S (hydrogen sulfide). See the recent post about this latter hazard using a citric acid fix from Anchell.
Fact: Yes and No. Color negative films have different speeds from differing emulsion speeds. This is true for ASA, ISO, and EI measurements. A slight tweak in speed may be had by adjusting contrast upward, but this is often so detrimental to the final tone scale that it is used with great caution and does not result in much speed. It looks like a push process right out of the box.
Color transparency films are slippery things when it comes to speed.
Go here: http://www.photo.net/making-photographs/film and scroll down to the Agfa 100 and 200 reversal film examples. Please note that the DMax’ of these two films differ by a considerable amount. This DMax difference is actually similar to what happens in a push process of reversal films. Densities above 3.0 are hard to detect visually, so if one designs two identical films, but with different fog levels, or coupler levels, the D-max difference can result in a different EI, with the same ISO speed. If you look closely, the actual threshold inflections of these two films are hard to determine, but if you imagine the film with the lower D-Max, having it raised, you will see that the EI goes down nearly matching the slower speed film.
Therefore, negative films have true EI and ISO speeds, but reversal films can have a vague definition applied to the speed leading to different speeds based on DMax. This is clearly seen in the example above.
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.
Fact: Yes and No. The image in an H&D curve is a macro image not usually seen in a 35mm or similar film image. It represents the general behavior of the film, but not the behavior when exposed to objects on the order of 1 – 100 microns in size, which is the case in real images. Therefore: edge effects change the curve shape of a film. Edge effects are only revealed in micro images or via micro densitometry. Bottom line – you may be missing a major image fault. It may have the speed and even the grain, but not the micro sharpness and contrast that meets the manufacturers specifications.
Fact: No. Interimage effects change the contrast of single colors and mixed colors. The neutral image always meets a certain given aim, but single and double color exposures may be vastly different in contrast than the 3 color image due to these effects. Therefore, several films with the same neutral scale may have vastly different interimage, contrast, and color saturation.
Fact: Yes and no. When a survey was run using hundreds of prints, transparencies and viewers at Eastman-Kodak, it was found that a majority of viewers picked the more saturated or intense colors unless flesh tones were included for reference. Even then, if the exaggeration made for tanned or glowing flesh tones, the more intense colors were picked. When presented with the original subject and color, the response was ‘oh!’. Then ‘but I liked the other print / transparency’ or whatever the photograph was. Inevitiably the average customer wanted the local garbage dump to look beautiful (approximate quote from a co-worker who ran the test.)
As a result, most consumer films are gaudier in color than professional films, a fact often noted on photo.net. More transparency films appear gaudier, but this is in part from two reversal film properties: 1) the higher contrast of reversal films, and 2) The method of color ‘corretion’ which requires higher color saturation to achieve a degree of realism without masking.
Fact: Yes they do, but not for the reasons you think. Editors like to see the image up-front, not a negative. They want the positive transparency to see how it fits into the ‘gally proofs’ and see what corrections must be made. Then, they alter the transparency using masks for higlights to adjust contrast, and correct color – in other words they adjust things to make the slide look more like a reproduction from a negative. In addition, transparencies fit into their work flow more easily than color negative, but they will take color negative as well. Most major magazines will take both types of original. If you give them a dupe positive, they use that for the editing process, and the negative original for the printing process. (This is not always true, but only a generalization)
Historically, this has to do with how printing was made. For color images, color separations needed to be made, which was somewaht easier for slides than for negatives. Modern digital equipment levels the differences and printing can be done from negatives just as well.
Fact: Yes and No. It depends on film. It is much harder to design a color transparency film than a color negative film wrt to sharpness and grain. Color negative films get edge effects, interimage effects, and grain improvements during color development from DIR and DIAR couplers. Transparency films must rely on the MQ for almost all image enhancements, and they come from edge effects and interimage effects. The color development step essentially goes to completion although there are tricks applied there as well. (In fact, this is where most published MQ and CD formulas for E6 films fall down, in the tricks department, which are proprietary)
The bottom line is that most transparency films appear sharper due to higher contrast images. This is explained by Mees and James “The Theory of the Photographic Process”. In addition, the tanning of the gelatin in some reversal films adds a degree of sharpness.
Fact: They use negatives, transparancies, cross processed film and even ECN motion picture film. They use dupe positives and negatives and all sorts of digital images. They used Kodachromes way back in the early days because that was the only color film they had to work with. Then they started using everything they got that was good.
Fact: Any kind of good film, positive or negative, shot well, can be used by a magazine. They use a lot of image manipulation to get the high quality you see on the printed page. And, they use CMYK images.
This article is based on two threads on photo.net and the content has been edited to include some valuable contributions from those threads. Thanks to those who participated and thanks to Ron.
Copyright 2004 Rowland Mowrey All Rights Reserved
Edward Richards , September 30, 2004; 07:52 A.M.
Jeff Medkeff , December 20, 2004; 03:03 P.M.
Rowland Mowrey 
, January 24, 2006; 09:08 P.M.
Friedemann Wachsmuth , January 22, 2007; 04:40 P.M.
Alan Rockwood , November 29, 2008; 12:15 P.M.
Rowland Mowrey , March 21, 2009; 10:56 P.M.
Rowland Mowrey , March 21, 2009; 11:01 P.M.
