ABSTRACT
Video imagery can be viewed in real time and the 2-D image produced by the lens falls either on a suitable photocathode surface, or on a two-dimensional focal plane sensor array of discrete photodetectors. The modulation transfer function of image tubes is determined by the photocathode material and characteristics of the scanning electron beam, so varies from centre to periphery. Specific requirements must be met when designing video lenses, whether for electronic drama production, outside broadcasting, electronic news gathering or electronic field production. Video lenses must also be optically corrected to compensate for the presence of various types and thicknesses of optical media behind the lens. Video cameras may use fixed focal length lenses of conventional design, such as double Gauss derivatives, often called prime lenses. Video cameras, especially the small single chip type, can easily be coupled to various optical systems. Video cameras, especially the small single chip type, can easily be coupled to various optical systems.
