طبيعة الفيلم الملون .. كتاب فن التصوير الفوتوغرافي

nature of color film

The photographer does not need to know the composition of the color film in order to be able to take a successful picture in color, but a simplified knowledge of the mechanism of producing the color image is useful to the photographer and helps him avoid gross mistakes.

The colored film consists of layers (as shown in Figure 3). These have been enlarged to a large scale for ease of explanation. The thickness of the upper four layers does not exceed the thickness of a black and white film. These layers have been given numbers from 1 to 6, starting from the upper layer.

Layer (1) consists of a coating that is sensitive to blue light only, and is not affected by green and red. When the film is exposed to anything that is blue in color or contains this color, it displays this layer in degrees directly proportional to the amount of blue present in it. The green and red colors do not affect them.

Layer (2), is a coating of yellow pigment that acts as a color filter that absorbs any blue color that penetrates layer (1). This layer does not intercept the green and red colors, and it is necessary because the first coating is very thin and semi-transparent, and without it, any blue color that passes to the next layers will display it because, ie, these layers are sensitive to this color.

Layer (3), only the green and red colors reach it, as the yellow filter above it absorbs all blue light that penetrates the first layer. This layer, i.e. layer (3), is sensitive to green light, not to red light. So any light green, or containing yellow, displays that layer. The colors yellow and turquoise (cyan) show it somewhat because both contain some green (see Table I).

Layer (4) is sensitive to red, and it is not sensitive to green and any red color or contains red such as magenta, brown, or orange. . . Etc., displays that layer to a degree commensurate with its redness. Any green color that penetrates layer (3) has no effect on layer (4), because that layer is not sensitive to green. The green and red light, which pass through the upper layers, penetrate the transparent layer (layer 5) and are absorbed by the light-isolating layer (No. 6).