INTRODUCTION
1. It is the purpose of this instruction book to describe means of establishing values for the best photographic reproduction of sound, and for maintaining a consistent control. Instruction Book 24416 is available for the use of those who do not have the special equipment necessary to make the rather precise tests described in this book.
2. All photographic sound records of any type must satisfy at least two requirements in order to give faithful reproduction. First, the wave form must be the same as that of the exposing light, and second, the amplitude must be well above the noise level. With the proper values of exposing light and developers, these two conditions can be met. In the variable-area system of recording, the requirement of wave shape similar to the exposing light takes the form of the problems of image spread and sharpness, while the requirement of amplitude well above noise level is the problem of contrast. These photographic problems can be solved by the choice of certain conditions. It is the object of these instructions to describe the test procedure to be followed in order to determine these conditions. A brief explanation of the theory involved is given first.
