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18X24 centimeter 4X5 inch 50 centimeter aerial cameras aerial photographic Air Service airplane camera altitude angle aperture apparatus astigmatic automatic camera axis bell crank camera body camera Fig camera mountings carried center of gravity centimeter plate cockpit color sensitiveness contrast curtain deRam desired direction distance distortion electric emulsions exposed exposure field film camera flying flying boat focal length focal-plane shutter focus focussing French front fuselage glass ground speed gyroscope hand camera hand operation hand-held camera Hurter and Driffield illumination interval lenses lever light magazine mapping mechanism meters method Metol motion motor necessary objects oblique observer ordinary orthochromatic overlap panchromatic paper photographic lens pilot plane plate camera plate changing position possible practice prints problem propeller rotating sensitometry sheaths shown in Fig side sight stereo stereogram stereoscopic surface tension tion vertical vibration wind wire
Page 116 - There has been some difference of opinion as to whether it is ever advisable to go further than this with plate cameras.
Page 58 - 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 18 - ... 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 all revealed, studied and attacked entirely on the evidence of the airplane camera. Toward the end of the war important troop movements were possible only under the cover of darkness, while the development of high intensity flashlights threatened to expose...
Page 389 - ... views have usually had to be drawn by an imaginative artist. Aerial oblique views possess the virtues both of pictures and of plans. They are destined to be extensively used in the study of architecture (Fig. 188). Cathedrals, castles, town halls, particularly those still in their cramped medieval surroundings where they can never be seen in their entirety from the ground, come forth in all their beautiful or quaint proportions from the airman's point of vantage. Stereoscopic aerial views are...
Page 394 - Mt. Vernon from the air. churches, shopping districts, parks, or factories. The future purchaser of lots in a distant boom town will no longer be satisfied with a map outlining the streets with high-sounding names. He will demand an authentic aerial photograph, showing the actual number of houses under construction, the streets, gutters and sidewalks already laid, the size and planting of trees.
Page 389 - ... any number of mere surface views. A vertical aerial photograph is most closely akin to a map, but has advantages over any ordinary surveyor's product. As a guide it is infinitely superior to the best draftsman's diagram, for it provides a wealth of detail whereby the traveller may definitely locate himself. At a single glance he notes the objects of interest within his radius of easy travel. The guide-book of the future will therefore be incomplete without numerous aerial views, both vertical...
Page 222 - Variation of average 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 o'clock — when it would be considered full daylight for purely visual observation — until noon, while there is a corresponding decrease by four o'clock.
Page 327 - ... 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 17 - ... immediate communication between plane and earth. The volume of work done by the photographic sections of the military air service steadily increased until toward the end of the war it became truly enormous. The aerial negatives made per month in the British service alone mounted into the scores of thousands, and the prints distributed in the same period numbered in the neighborhood of a million. The task of interpreting aerial photographs became a highly specialized study. An entirely new activity...
Page 39 - ... 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...