Abstract: A zoom lens system according to the present invention comprises, from the object side to the image side, a first lens unit with a positive refractive power including a negative high dispersion lens element and a positive lens element; a second lens unit with a negative refractive power consisting of two or three lens elements including a positive high dispersion lens element and a negative lens element, and having at least one aspherical surface; and a third lens unit with a positive refractive power consisting of five or less lens elements including a negative high dispersion lens element and one or two positive lens elements located on the object side of the negative high dispersion lens element, and having at least one aspherical surface. With the lens arrangement, a compact high-zoom-ratio zoom lens system having a high aberration correction performance is realized.

Abstract: A camera system including an objective lens system and a camera body comprises: a movable lens unit included in the objective lens system to act as a variator for varying a focal length of whole of the objective lens system; a CCD for receiving light passed through the objective lens system to pick up an image formed by the objective lens system; a motor for shifting the CCD along the optical axis of the objective lens system; a first detector for detecting a position of an image formed by the objective lens system to produce a defocus signal representing the position of the image; a second detector for detecting a position of the movable lens unit along the optical axis to produce a lens position signal representing the detected position of the movable lens unit; and a controller for controlling the motor in accordance with both of the defocus signal and the lens position signal to bring the light receiver to the position of the image formed by the objective lens system.

Abstract: A wide-angle zoom lens system comprises, from the object side to the image side, a first positive lens unit being stationary on an optical axis during a zooming operation, a second negative lens unit shifting along the optical axis during the zooming operation, a third positive lens unit being stationary on the optical axis during the zooming operation, and a fourth positive lens unit shifting along the optical axis during the zooming operation, wherein the refractive power of the first and second lens units fulfills the predetermined conditions.

Abstract: A variable lens system has three lens unit whose refractive powers are positive, negative and positive from an object side to the image side. Each lens unit consists of at least two lens elements. The central lens unit and the image side lens unit are shifted along an optical axis during a zooming operation. The lens system fulfills the conditions: ##EQU1## wherein fS, Z, and Y' represent the shortest focal length, a zoom ratio and an image height, respectively, of the lens system. .phi.1 and .phi.2 represent refractive powers of the object side and central lens units.

Abstract: A collimator lens of a single lens type having a convex aspherical surface on the collimated light side and a plane surface on the condensed light side fulfills the following conditions: ##EQU1## wherein f represents a focal length of the collimator lens; t represents an axial distance of the collimator lens; NA represents a numerical aperture of the collimator lens; n represents a refractive index of the collimator lens; r represents a radius of curvature of the convex aspherical surface in the paraxial region. According to the collimator lens of a single lens type thus configurated, short axial distance and light weight can be realized, which makes it possible to be formed by the liquid glass drop method. In addition, the collimator lens of a single lens type which keeps good balance of an axial aberration and an off-axial aberration is obtainable.