Abstract: A three tube type color television camera comprises an optical system using a prism for the three color separation in which an image of a test pattern is introduced into an optical path of the camera through the optical system. The optical system has an incident plane onto which the image of the test pattern is projected by a pattern projector closely located with respect to the incident plane.

Abstract: A zoom lens apparatus comprises sensors for detecting relative positions of a variable power lens group and a compensating lens group, a memory for pre-storing compensating data peculiar to the zoom lens apparatus, a control circuit and driving parts for moving the variable power lens group and the compensating lens group. The control circuit compares position data set by a variable power setting operation and position data obtained from the sensors and outputs signals for controlling the relative positions of the variable power lens group and the compensating lens group based on the compensating data read out from the memory. The driving parts vary the relative positions of the variable power lens group and the compensating lens group responsive to the output signals of the control circuit.