GB1302899A - - Google Patents

Abstract

1302899 Panoramic cameras EMI Ltd 15 April 1970 [26 April 1969] 21407/69 Heading G2A In a panoramic camera in which light is passed through a rotating prism assembly 11 and lens system 12 through a slit 13 on to a moving film 14, the system 12 is formed as a variable magnification zoom lens. As shown, the assembly 11 is a double Dove prism arrangement driven by a motor 18. The film is driven from spool 15 to spool 16 across the variable slit 13 whose width is controlled by a motor 20. Image motion compensation corresponding to aircraft movement when the camera is used in an aircraft is provided in the along track direction by a motor 21. Across track control by motor 22 compensates for angular motion of the prism assembly. The magnification of the zoom lens assembly 12 is controlled by the position of the movable lens element as determined by the drive motor 19. In arrangements having a lens of fixed focal length, the magnification of the lens decreases with increasing angle of sweep of the prism assembly as the object distance increase. Thus the image becomes compressed towards the ends in both the across track and along track directions, Fig.2a (not shown). This is compensated for in the present arrangement by varying the magnification of the lens system. Motors 19, 20, 21 and 22 are all controlled from a central control 17 which receives a signal representing the aircraft velocity/height ratio, and also a function of the prism scanning angle from a pickoff device 25. Thus the lens magnification, slit width, and film transport in the along and across track directions are all controlled in synchronism in a co-ordinated manner.