How to Operate a Digital Camera

The virgin emulsion is formed analogously to slides: three layers of black and white negative, each of them sensitive to a primary color. The exposure gives way to the separate registration of the basic colors in each point of the scene. The first developing produces three negative black and white images (2). Afterwards, each layer is associated with it's corresponding complementary pigment (without a reversal of the registered information). The amount of pigment formed is proportional to the density of it's corresponding layer (color developing); therefore, after the image is set, each basic color appears registered as a variable density of it's complementary color (3). The image we see in a negative has inverted colors: the ones that were blue in the scene are now yellow, what was red in the scene is cyan in the image, and what was green appears as magenta (and vice versa). The color negative has an orange base color. This printing mask is used to compensate more sensibility of printing paper to green and blue.

Characteristic Contrast and Exposure Latitude: Negative color emulsions have a normal or low characteristic contrast. The exposure latitude, therefore, is much wider than with slides. As in black and white, the exposure level that the photometer advises produces a minimal density to obtain quality prints, in the developed negative. Also, if we represent a negative colors operation as a ladder, this is very similar to the one seen when talking about the negative. Therefore, with a medium sensitivity negative, we have a (approximate) latitude of two exposure values for levels under optimal (shadows) and three exposure values for superior levels (lights).

Exposure Level, Contrast and Color: In a print, the brightness characteristics, tone and saturation of the final image depend on that of the developed negative and the necessary adjustments for it's printing on paper. This implies that we have a greater tolerance than with slides: an error in the exposure, or a dominating color can be corrected in the lab.

The brightness and tone range that can be reproduced by reflection on a sheet of paper is more limited than with slides. This is not a consequence of the negative's characteristics, but of it's reproduction on paper. A well used negative can contain a brightness and tone variety similar to that of a slide: cinematographic copies, which start with a negative, are a good example of this. On pepper, the brightness and tones are more close to each other, more compressed. The relationship between the negative and print is very close. To take advantage of all the exposure latitude, which is were we fin detail and color, we have to be sure that the shades and lights of the brightness interval we're wanting to cover find themselves in the underexposure and overexposure limits (4.3.1.2). On the other hand, our developed negative's tonal ladder will only be partial, with loss of contrast and detail.

Once developed, a quality negative lets us decide, without asking the original, the final aspect we want our image to have. With printing we have a very exact control of tones, saturation and brightness, as long as there is an effective control of the way the negative is printed.

Printing can correct -but also accidentally introduce- light prevailing colors. To obtain a correct balance of tones, the color of the printing light has to be adjusted according to the negative and paper's characteristics. The prevailing colors can be detected by seeing neutral color zones in the image (grays): when these are dyed with a determined color, the negative has been printed with a prevailing color, that also has the effect of softens tones rich in it's complementary color.