Working principle of film camera

First of all, the core principle of any film is that silver halide emulsion reacts after seeing light, and small silver halide reacts to a certain extent and polymerizes into large particles. The stronger the light received, the greater the degree of polymerization/particle.

If the black-and-white film is developed so that the silver halide on the negative separates out the silver simple substance, then the large particle part is opaque because of the large amount and high density of metallic silver, and then it is fixed and washed away the unreacted silver halide, thus making the black-and-white film.

Color negative, at least three layers, coated with silver halide sensitive to different colors of light (many fujifilm have four layers, which are not only sensitive to red, green and blue, but also sensitive to cyan).

When the red light reaches the negative film, only the silver halide emulsion layer sensitive to red will react, and the other two emulsion layers will remain unchanged, so that the three-color light can be received independently without relying on any filter.

The red emulsion layer is only sensitive to red light, and other colors will not change.

So how to make it colorful?

It's a substance called chromogenic agent, which is very complicated. In short, film can perceive red light and react with silver halide which is sensitive to red light. When developing, the special red developer reacts with the silver halide layer to form a red image, and then the red photosensitive silver halide is completely washed away, leaving only the developer on the negative, and so are other colors, thus forming the color negative-color negative, which is different from the black-and-white negative in color negative.