Processing Images: C-41 Color Negative Film Processing
In your camera, light exposes the film, creating a latent image. In order to view this image, the film must be developed, fixed and washed. If you are photographing with film, you may find that having it processed at a lab saves time and gives desirable results. You may, however, prefer to process your own film for 1) increased control over how your negatives look (For example, you can alter the development time to increase or decrease density and/or contrast), and 2) more options when photographing (For example, you can rate the film speed higher in your camera and compensate for this with processing). Refer to the book for information about film, descriptions of small tank processing, general work area, chemicals, safety and storage issues, and black and white film processing. Here, on our web resources, we describe the C-41 color negative development process.
Most commercial labs process color negative film with fast turnaround and at reasonable cost. However, if you plan to shoot a large quantity of color film, self-processing can be less expensive. If you want to control the development process, you may want to process the film yourself. Color processing is similar to black-and-white processing. 35mm-processing in the small tank utilizes the same method of loading the film on reels in a tank, pouring in chemicals and agitation, but with different chemicals, times and temperatures. Color has less latitude than black-and-white processing: processing times and temperatures must be spot on. The developer temperature must be 100˚F, with accepted variance of only ±1/4 . When processed correctly, negatives benefit from self-processing. The colors will be more saturated. The more often you process film, the greater understanding you will have of how time and agitation can produce specific results.
Kodak’s C-41 is the most common process for developing color negative films (Look for “Process C-41” on the film box or cartridge.). The C-41 process involves particular chemicals at particular times and temperatures.
First a water presoak softens the film to allow for more consistent developing. The developer makes the film’s latent image visible by changing exposed silver halides into metallic silver and activating color dyes in the film’s layers. While the time and temperature of development for black and white film depends upon the brand and film speed, all C-41 film is processed at the same time and temperature, regardless of manufacturer or ISO. This means that two different types of color negative film can be processed in the same tank. The second step in the C-41 process, bleaching, breaks down the silver image. Fixing removes the silver, leaving a color image made of magenta, yellow and cyan layers. A water wash removes fixer residue. The final step, stabilizer, protects the dyes from fading and promotes uniform drying. Developer, bleach, fix and stabilizer are available at mail order photographic suppliers. The bleach often ships ready-to-use and the others are easy to mix. We recommend mixing the developer in 5-gallon batches and the “kit” in one-gallon brown jugs.
The bleach, fixer and stabilizer make up what is referred to as the “kit’. Instead of thinking of each chemical individually, these three are treated as a set. Together, they have the capacity to process a certain quantity of film. For example, a kit made up of three 1-gallon containers can process 1800 square inches of film. While the developer must be discarded after processing, the bleach, fixer and stabilizer are returned to their respective jugs after each use. Note the amount of film processed (in square inches) on a running tally, such as this C-41 processing log. When the chemicals reach their processing capacity, throw them out and mix a new “kit”.
Push Processing Film
Push processing or up-rating film means underexposing the entire roll of film by one or more stops, then over-developing by 25-50% (per stop decrease). Increase development only. All other chemical steps remain the same.
Color negative films have greater exposure latitude than black-and-white films and can be pushed to reasonable lengths with good results. Processed negatives may have increased graininess, image contrast and color saturation and diminished shadow detail. Only push-process if these formal qualities fit the conceptual goals of your subject.
Evaluating Color Negatives
Evaluate color negatives for density. Negatives will clearly be over- or under-exposed, too dark or too light. Other qualities – image composition, content, color and lighting – are harder to evaluate. This is because the negative’s reversal of colors and tones makes the image difficult to interpret. Furthermore, the orange mask, an overall coloring to the film that helps improve color reproduction by reducing contrast, obscures the image color. Make a contact sheet to evaluate color images.
E6 color slide films can be cross-processed in C-41 chemistry to produce negatives. Follow the standard C-41 temperatures and times. Cross processing creates drastic shifts in color, contrast and saturation and the color grain (or dye) will be very defined and enlarged. Images usually have a greenish color cast and extreme contrast, characteristics that lend a surreal or bleached quality to image content. Be aware that a kit of C-41 chemistry used to cross process color slide film should not be re-used to process color negative film. The chemicals should be reserved for additional cross processing purposes or discarded.