THE GENERAL PRACTICE OF INFRARED PHOTOGRAPHY
There is no fundamental difference between the practice of infrared photography and that in which visible light is used. Anyone equipped for photography with ordinary, orthochromatic, or panchromatic plates or films can make infrared photographs without investing in any extra equipment other than a filter for use on the lens of his camera. Naturally, certain precautions must be taken because of the sensitivity of the materials to the invisible radiations, but these do not involve any unusual practice. In fact, in addition to the filter, the only other thing which the general photographer might wish to purchase is a special infrared darkroom safelight, but even this is unnecessary if it is not an inconvenience to operate in total darkness while loading and developing. If unusual work is to be done, it may be desirable to buy special lenses, plates, and films; to compound particular developers; and so on. It is often necessary to do this for uncommon uses of ordinary photography, however, and so the use of the infrared does not place any unusual demands on the photographer's pocket or skill. It cannot be emphasized too fully that for general infrared photography the equipment and experience acquired in the course of normal photographic practice are perfectly adequate.
The chapters of this book are devoted to the principles and practice of infrared photography in its manifold applications. In order to make the most of the subject one should study these chapters. It is believed, however, that it is of some value to bring together in one chapter a summary of the chief points to be borne in mind in the use of the infrared for general photographic purposes. It is the object of this chapter to present this material in a readily accessible form. References will be made to the other sections of the book where the subjects are treated in greater detail.