Business screen magazine (1944)

m mm\\ A Study in Light Contrasts + bv Iti4-haril P. Buoh, Lt.. US^TR rHE ABILITY to see at night is part of the experienced sailor's stock in trade. Unlike the average landsman, he has lenty of opportunity to develop his night visual ipacity. Good night \ision is the product of spericnce and training rather than innate bilitv. One of the best night vision instructors t the training school in New London was a ;tired chief signalman, who at 60 could see ettcr at night than any youngster of 17, He lainicd that he had picked up the knack of off-center" vision, or looking "cock-eyes," as e put it, on his first tour of duU off the ;hina coast, many years before. The rest was imply practice. For some time, he kept his know-how" a secret and derived a tidy revenue ly betting with unwary shipmates on his uncanly ability to pick up sightings far in advance if anyone else. Ultimately his secret came out, ly dark-adapting their eyes and learning the iff-center night scanning technique, many of his hipmates became even more owl-eyed than he, l%'h('n war slarlod. on a 24-hour basis, ;ood night vision became vital to the fleet. In I few short months, the Na\'y had to teach the undamentals of night vision to thousands of ncn, most of them with little or no experience n using their eyes at night. The night vision ynthctic trainers and the first Navy training ilm on night vision had to take the place of ■xperiencc. so far as thousands of future night ookouts were concerned, \iewed critically, the irst Xa\7 night vision film has its visual limtations. The sound track and the animation war the burden of teaching. But in 24 minutes t has told thousands of "boots" what they had lo know about night vision. Better still, it was finished and distributed early enough in the war to enable them to put this knowledge to good use. A more recent condensed version does the same basic job in five minutes. While the lookout film was doing its work, the course of the Pacific war made night vision training for naval pilots and aircrew a necessity. Early in the Solomons Campaign the Jap air force began to strike at night. The patrol ^)lane pilots and crewmen who went after those first night raiders required no sales talk on the need for night vision training. Today, with night intruder missions on the upswing, and after-sunset carrier strikes increasing, naval airmen arc discovering that night vision training is good life insurance, A new training film about night \ision for airmen is designed to assist in teaching night vision essentials to pilots and air crewmen aboard carriers and at advanced bases, where the installation of night vision trainers and other synthetic devices would be impractical. The original intention was to edit pertinent material from the Navy lookout film and from night vision films produced by the Army and the British. For two reasons this idea proved to be impractical. First, there was no visual material available on the special subjects peculiar to night flying. Second, a different type of audience was involved wliich called for different treatment and different situations. Night aerial effects were needed but none of die librar) material was suitable. ,-\ll that could be culled from existing films was animation footage on the workings of the eye, a matter of secondary interest to flying men. .\t this stage of planning, a five-day conference on night \ision training was conducted by the Commander Fleet Ah, Quonset, at which Wing Commander K, A, Evelyn, head of the RC.^F Biophysics Laborators in Montreal, Canada outlined his entire night Wsion instructor course. Dr. Evelyn, a scientist of tremendous energy and ability, is an outstanding leader in night vision training for aviation personnel. Borrowing liberally from the night vision training ideas develo|)ed under the Commander, Submarines .•\tlantic Fleet, New London, and from the lessons which the R.\F had learned in their night bombings of Germany, he added the results of his own research and organized the best training syllabus then available. His work was invaluable not only for the training film, but in standardizing the entire Navy training program. Within the limitations of the motion picture medium, the new film on night vision for airmen covers some of the basic lesson taught first hand in the Evelyn Two-Dimensional Trainer. This trainer consists of sharp two-dimensional shadowgraphs of a countryside panorama, or seascope, projected, ten times magnified, by a controlled illuminator lamp against a large screen in a blacked-out classroom. Completely blind at first, the audience, during a thirtyminute lecture and demonstration, goes through the various stages of dark adaptation ; first, "contrast perception," the primordial night visual experience; second, "simple form perception," in which larger objects of characteristic shapes are observed ; and, finally, complete adaptation, in w-hich details become more clear, and "complex form perception" is possible. The first of these stages, "contrast perception," is the primary \isual task of the night lookout, who in dim starlight sees a black blot on the dark horizon, and of the pathfinder pilot, barely able to make out the difference between a white beach and a pitch-black sea. At the second stage, large forms of characteristic shape are identifiable, particularly if they are familiar, or if the possibilities of choice are limited, -A Navy PBV can be distinguished from a Jap "Zekc," for example, if these are the only alternatives. More details become apparent, with full adaptation, and the experienced pilot, if well briefed, can effectively attack his ground target, using visual clues not perceptible to the unprepared eye, .As a mediimi for illustrating these gradations of mght visual acuity, the motion picture film can never compete with the Evelyn trainer. This fact was recognized at the outset. The basis of photography is light. The trainer illustrates occular phenomena occurring at light levels far below those which a camera can record on film. The trainer has the further advantage of demonstrating with startling impact, and at first hand, the total effect of complete dark adaptation, .After a half hour in the trainer, one eye is covered while the odier is exposed to brilliant white Hght, Then darkness is restored. The eye that was covered sees the silhouettes as well as ever. The exposed eye is completely blind. Here is a direct experience, compared to which a motion picture is like one of Plato's shadows on the wall of the In the irainin^^ fllni. on the other hand, it is possible to explain by [Turn to page tra] A REPORT ON NAVY TRAINING FILMS 69