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Types of Visual Aids and Their Uses 121
Selecting Film Stock. The selection of film should be given some consideration. The ordinary negative stock should be used for pictures of which several prints will be required. The majority of amateur producers, however, will not need additional prints and will find the reversible film to be more economical. Prints can be made from the reversible film, and the process is reasonably satisfactory. The reversible film, as the name suggests, is converted from negative to positive in the processing and comes back to the producer ready for projection.
The reversible film is divided into three principal classifications: orthochromatic, panchromatic, and super-sensitive panchromatic. The first is being replaced by "Verichrome" and "Plenachrome" film, which are satisfactory for all general purposes. The panchromatic film is used extensively for pictures where reasonably good light is available for the exposure. The super-sensitive film should be used in poor light or for pictures taken in artificial light, as it is much more sensitive to artificial light than is either regular or panchromatic film.
There are natural-color films available which add much to the value of those subjects in which color is important. The color films are a little more expensive than films for photographing in black and white and may not be duplicated as easily. The proper projection of color film requires stronger illumination than is necessary for projecting ordinary film, but the new projectors which permit the use of highintensity lamps project color well, even in large rooms. It is seldom desirable to combine ordinary and color film in the same subject. If color is used in the same film with black and white scenes, the black and white sequence should make up the first part of the film and the picture should end in color. If the color is inserted between scenes in black and white, the change from color to black and white will be unsatisfactory.
Shooting the Picture. After the scenario has been arranged and the equipment and film selected, the important task is that of taking the scenes to be included. There are a few simple rules to be followed which will be of assistance to the amateur, and these are mentioned below. Experience is a dear teacher and those who operate the camera without first giving attention to certain simple suggestions may find that very expensive film stock has been wasted.
1. Use a reliable exposure meter to determine the proper lens setting. This cannot be overemphasized and such a meter should be used for each situation. Light values are difficult to guess, even for the professional.