VARIABLE POWER OPTICAL SYSTEM

• Main Author: SHIODA RYO
• Format: Patent
• Language: English; Japanese
• Published: 07.09.2017
• Subjects: ACCESSORIES THEREFOR; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USINGWAVES OTHER THAN OPTICAL WAVES; APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FORPROJECTING OR VIEWING THEM; CINEMATOGRAPHY; ELECTROGRAPHY; HOLOGRAPHY; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHOTOGRAPHY; PHYSICS

PROBLEM TO BE SOLVED: To provide a variable power optical system in which aberrations are satisfactorily corrected and which has a small F-number, while reducing variation in an air gap distance between a first lens group and a second lens group when varying power.SOLUTION: A variable power optical system of the present invention comprises a first lens group G1 having positive refractive power, second lens group G2 having negative refractive power, third lens group G3 having positive refractive power, fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power in order from the object side. In the variable power optical system, when varying power from a wide-angle end to a telephoto end, an air gap between the first lens group G1 and the second lens group G2 increases, an air gap between the second lens group G2 and the third lens group G3 decreases, an air gap between the third lens group G3 and the fourth lens group G4 is fixed or changes, and an air gap distance between the fourth lens group G4 and the fifth lens group G5 changes. The variable power optical system satisfies prescribed conditional expressions.SELECTED DRAWING: Figure 1 【課題】変倍時における第１レンズ群と第２レンズ群との間の空気間隔の変化を小さくしつつ、諸収差が良好に補正された、Ｆナンバーの小さい変倍光学系を提供する。【解決手段】本発明は、物体側より順に、正の屈折力を有する第１レンズ群Ｇ１、負の屈折力を有する第２レンズ群Ｇ２、正の屈折力を有する第３レンズ群Ｇ３、負の屈折力を有する第４レンズ群Ｇ４、正の屈折力を有する第５レンズ群Ｇ５を有し、広角端から望遠端への変倍の際に、前記第１レンズ群Ｇ１と前記第２レンズ群Ｇ２の間の空気間隔が増大し、前記第２レンズ群Ｇ２と前記第３レンズ群Ｇ３の間の空気間隔が縮小し、前記第３レンズ群Ｇ３と前記第４レンズ群Ｇ４の間の空気間隔が一定もしくは変化し、前記第４レンズ群Ｇ４と前記第５レンズ群Ｇ５の間の空気間隔が変化し、所定の条件式を満足することを特徴とする変倍光学系とした。【選択図】図１