Camera system with automatic variator compensation in a zooming mode of operation

In a camera system, the improvement comprising:

• an objective lens means for producing an image;
• varying means for changing focal length of the objective means without use of a compensator lens;
• receiving means for receiving light which has passed through the objective lens means to pick up the image formed by the objective lens means;
• means for detecting the focal length of the objective lens means;
• and
• means for shifting the receiving means in accordance with the detected focal length to compensate for any image position deviation brought about by varying the focal length, thereby causing the receiving means to serve the function of a compensator lens.

In a camera system, the improvement comprising:

• an objective lens system comprising, from an object side, facing an object to be imaged, to an image side, facing an image formed by the lens system:
• a first positive lens unit being stationary on an optical axis of the objective lens system during a zooming operation;
• a second negative lens unit being movable along the optical axis for varying a focal length of the objective lens during the zooming operation;
• a third positive lens unit being stationary on the optical axis during a zooming operation;
• receiving means for receiving light which has passed through the objective lens system to pick up an image formed by the objective lens system;
• and
• means for shifting the receiving means in accordance with movement of the second lens unit to compensate for any image position deviation brought about by the movement of the second lens unit.

A combination of an optical zoom system and an image recording system of a lightweight and compact configuration comprising:

• a zoom lens system for providing a variable focal length having a plurality of lens units including one movable lens unit moving along an optical axis to provide the variable focal length zooming, while the other lens units remain stationary;
• means for monitoring the position of the movable lens unit to provide a signal representative of the focal length position;
• sensor means for receiving an image of an object from the zoom lens system and providing an image signal;
• means for automatically calculating a focus signal from the image signal;
• means for calculating a variation signal of the focal length from the signal representative of the focal length position of the movable lens unit;
• drive means for moving the sensor means along the optical axis;
• and
• control means for controlling the drive means in response to the output of the focus signal and the variation signal to drive the sensor means to a compensated and in-focus position relative to the focal length of the zoom lens system and the in-focus position of an object.

A camera system including an objective lens system without a compensator lens unit, comprising:

• an objective lens system fulfilling the following conditions:
• {1-(Z.sup.1/2 /10){.times.0.9<.vertline..phi.II/.phi.S.vertline.<{1+(Z.sup.1/2 /100)}.times.0.9 0.3<.phi.III/.phi.S<1.2
• wherein:
• Z represents a zoom ratio of said objective lens system;
• .phi.II represents a refractive power of the second lens unit;
• .phi.III represents a refractive power of the third lens unit;
• and
• .phi.S represents a total refractive power of the objective lens system in the shortest focal length condition;
• the lens system with an object end towards an object to be imaged by the lens system and an image end towards an image formed by the lens system comprising, from the object end:
• a first lens unit having a positive refractive power and being stationary on the optical axis;
• a second lens unit, which is a movable lens unit, having a negative refractive power and movable along the optical axis to serve as a variator lens for varying a focal length of the objective lens system;
• a third lens unit having a positive refractive power and being stationary on the optical axis;
• means for moving the movable lens unit to change its position and thereby vary the focal length of the objective lens system;
• means for detecting a position of the movable lens unit along the optical axis of said objective lens system to produce a lens position signal representing the position of the movable lens unit;
• and
• a camera body having mounting means for attaching the objective lens system, the camera body comprising:
• means for receiving light which has passed through the objective lens system to pick up the image formed by the objective lens system;
• means for shifting said light receiving means with respect to the camera body along the optical axis of the objective lens system;
• and
• means for controlling the shifting means in accordance with the lens position signal to make the light receiving means move to compensate for any image position deviation brought about by the movement of the movable lens unit in varying the focal length of the objective lens system, the light receiving means thereby serving the function of a compensator lens.

An improved objective lens system comprising, from an object side, facing an object to be imaged, to an image side, facing an image formed by the lens system:

• a first positive lens unit being stationary on an optical axis of the objective lens system during a zooming operation;
• a second negative lens unit being movable along the optical axis for varying a focal length of the objective lens during the zooming operation;
• a third positive lens unit being stationary on the optical axis during a zooming operation and including an air space within the lens unit of sufficient length along the optical axis to correct distortion and field curvature;
• receiving means for receiving light which has passed through the lens units to pick up an image formed by the lens system;
• and
• means for shifting the receiving means in accordance with movement of the second lens unit to compensate for any image position deviation brought about by the movement of the second lens unit, the receiving means thereby serving the function of a compensator lens.