Patent ID: 9671597
Date: 2017-06-06
CPC Classifications: G02B,H04N

Claim:
1. A zoom lens system comprising, in order from an object side to an image side: a first lens group having positive refractive power and a focus function; a second lens group having negative refractive power, which moves when changing a magnification; a third lens group which moves when changing a magnification; a fourth lens group having positive refractive power, which is fixed when changing a magnification; a temperature sensor; and a controller, wherein the following condition (1) is fulfilled: where M the controller is configured to move an entire or a part of the fourth lens group at least at the wide-angle end based on a temperature change measured by the temperature sensor so as to correct a change in focus position with the temperature change, the fourth lens group includes, in order from the object side, three positive lenses, and each of the three positive lenses fulfills the following conditions (7), (8): where νd represents Abbe number of a lens material, and θ