كيفية تظهير الأفلام الملونة .. كتاب فن التصوير الفوتوغرافي

Color films endorsement

The purpose of this paragraph, which is related to the color film endorsement process only, is to give a brief idea about that process, and it is not intended to give the necessary instructions for endorsing this type of film. If you want to do the endorsement process yourself, then you have to get instructions from the makers of these films, as they give ample instructions on how to endorse amateurs.

The endorsement process at home is not very difficult, but we do not recommend it unless you are skilled in manual work, and if you shoot several color films a month. Also, the solutions needed for this process are expensive and spoil quickly. The amateur who shoots color film from time to time will find that it is less expensive and more practical to send the film to a laboratory for endorsement.

The endorsement process is summarized in several successive operations, the first of which is: endorsement of the film with a normal solution as for black and white film, then the film is re-exposed to a white light. During that process, the effect of the first exposure of the film is reversed. This process is carried out by dipping the film in a special solution for color rendering, which is a chemical compound that reacts with sensitive shades to form dyes that are commensurate with the degree of deposition of silver salts resulting from the previous endorsement process.

And we get the final color image by projecting white light on the negative crystal, where a filtering process takes place for the different colors that make up the white light, as it is printed on special paper.

Temperature and color balance

The eye has the ability to adapt to light and translate it with the help of the mind into colors. It sees the color white, despite the difference in its degree of whiteness, as white, and the white daylight is not the same at different hours of the day, and despite that, the eye sees it as white at all times. The light of a candle appears yellowish in daylight, but at night, when the candle is the only source of light, it appears white, and the eye also sees it. As for the film, it is recorded as yellow in both cases.

This adaptation color film could not do; It is intended to depict white color if the characteristics of this color meet in it, and any change in the degree of its whiteness will be captured by the film as it is. It is designed to depict white as white when it reaches a certain degree of whiteness, and this is called the color temperature (*), and it is measured by the Kelvin scale, which starts from the absolute zero degree (i.e. -273). This color temperature measures how close it is to the perfect balance of the three colors. in it .

In order to photograph objects in their true colors, the three coatings of the film must be balanced for use in a light similar to the light in which the photograph will be taken. It is impossible to secure a single film that can cover
All light conditions, and recording colors in a balanced manner, so the makers of these films created four types of them that cover almost all conditions.
These types are:
The film prepared for shooting in daylight, the film of type A film (A), the film of type B film (B), the film of type F film (F).

1- Daylight Film
This type of film balances its colors to the temperature of 6000 K (Kelvin degree), which is the color on a sunny day in the northern hemisphere at noon. And when the sun is tilted in the early morning or in the late afternoon, the light is less hot (5000 ° K) and tends to be red, and the image taken at these times is tilted to orange or red.

2- Type A film A
This type of film has colors balancing the color temperature of 3400 ° K, which is the light given off by the Photoflood Lamp and is used in indoor photography where the power of electricity is weak.

3- Type B film B
This type of film has color balancing colors at a temperature of 3200 ° K. It is distinguished from class A in that it is used for filming with less powerful lamp light, which makes it last longer, and it is used in interior photography.

4- Type F film
This type of film has colors that balance the color with a temperature of 3800 ° k, which is the heat of the light that is given by a regular flash bulb, and it is widely used by amateurs and professionals alike.
We point out here that this type of film is intended for filming with a flash lamp only, and not with an electronic lamp that gives a light close to daylight, with which it is necessary to use color film prepared for daylight.