GB736830A - Improvements in or relating to aircraft cameras for taking pictures bearing an image defining the position of the nadir point - Google Patents

Abstract

736,830. Photographic cameras. NISTRI, U. June 19, 1953 [June 20, 1952], No. 17031/53. Class 98 (1). A camera for use in planimetric air photography includes means whereby recordings are made on the photogram plane which can be used to evaluate the angular inclination of the camera axis at the time of exposure. As shown in Fig. 2, the camera has an objective b with principal axis PS which is perpendicular to the plane 4 of the photogram when the aircraft carrying the camera is in level flight. Gyroscopes O<SP>1</SP> and O<SP>11</SP> are provided with their primary axes orthogonal; each axis is parallel to the plane 4 and in a common plane with the axis PS which common planes respectively intersect the plane 4 in lines X and Y meeting at the centre P of the photogram. A prism 21 (or 2<SP>11</SP>) is attached to each primary axis and reflects into a lens 6<SP>1</SP> (or 6<SP>11</SP>) light from a collimator 31 (or 3<SP>11</SP>) so that this lens images on the photogram a grid disposed in the light path in the collimator. Thus grid images N<SP>1</SP> and N<SP>11</SP> are formed on the photogram in positions dependent upon the degree of tilt of the camera axis PS at the time of exposure; the intersection N of lines drawn through these images parallel to the axes X and Y respectively represents the nadir point, the distance PN being the nadir distance. In a modification, a universal mounted pendulum is combined with the collimator and explores the gyroscopes. Another form is described in which the collimator is carried by a universal mounting which is eccentrically controlled by a gyroscope. Specification 669,959 is referred to.