Airplane Photography (Google eBook)

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J.B. Lippincott, 1920 - Aerial photography - 422 pages
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Page 22 - The airplane has totally changed the nature of warfare. It has almost eliminated the element of surprise, by rendering impossible that secrecy which formerly protected the accumulation of stores, or the gathering of forces for the attack, a flanking movement or a "strategic retreat." To the side having command of the air the plans and activities of the enemy are an open book. It is true that more is heard of combats between planes than of the routine task of collecting information, and the public...
Page 63 - Fig. 6. A diagram to show how the focal length of a lens is measured. As focal length is to height so is the width or length of plate to the width or length of the ground covered. The scale is therefore directly proportional to the focal length and inversely proportional to the altitude. f = focal length of the lens, h = height at which photo is taken, w = width or length of plate in inches.
Page 23 - By the close of the war scarcely a single military operation was undertaken without the preliminary of aerial photographic information. Photography was depended on to discover the objectives for artillery and bombing, and to record the results of the subsequent "shoots" and bomb explosions. The exact configurations of front, second, third line and communicating trenches, the machine gun and mortar positions, the "pill boxes," the organized shell holes, the listening posts, and the barbed wire, were...
Page 44 - ... the shutter speed required; means of supporting the camera to protect it from the vibration of the plane. Mosaic maps are built up from a large number of photographs of adjacent areas. In addition to the above requirements, mosaic maps demand lenses free from distortion and covering as large a plate as possible, in order to keep to a minimum the number of pictures needed to cover a given area; means for keeping the camera accurately vertical, and means for changing the plates or films and resetting...
Page 227 - Fio. 101.—Variation uf uvenige daylight intensity during the day. daylight during the course of the day and during the course of the year. Measurements showing typical variations from morning to night are exhibited in Fig. 101, from which it appears that there is an increase in illumination of four to five times from 8...
Page 332 - ... to 45 degrees from the horizontal. This low altitude necessitates very short exposures, to avoid movement of the image. The picture may be taken either the long or the short way of the plate, depending on the character of the object and the information desired. It is to be noted that successive oblique pictures cannot be mounted to form a continuous panorama—this being possible with obliques only if they are taken from one point, as from a captive balloon.
Page 50 - English practice, which was followed in the training of aerial photographers in America, where exactly similar conditions held at the start with respect to available lenses. French glass and lens manufacturers did succeed in supplying lenses of longer focus (50 centimeters), in numbers sufficient for their own service, although never with any certainty for their allies.
Page 104 - J is a snap catch for holding the front door of the camera open. The operations with this camera are three in number. Starting immediately after the exposure, the camera is pointed lens upward and the plate changed by pulling the inner body of the magazine out and then in; next the shutter is set; then the camera is pointed, and finally exposed'by a gentle pull on the exposing lever.

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