VARIABLE POWER OPTICAL SYSTEM AND IMAGING APPARATUS INCLUDING THE SAME

• Main Authors: FUJIKURA TAKASHI, SATORI TOSHIYUKI, YANAI TETSUYA, ZEN YUKI
• Format: Patent
• Language: English; Japanese
• Published: 04.10.2018
• 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 whose front lens diameter is small and chromatic aberration is satisfactorily corrected, size is small, and image formation performance is high, while shortening the entire length of an optical system, and to provide an imaging apparatus including the variable power optical system.SOLUTION: The variable power optical system comprises a plurality of lens elements and includes, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and at least one lens group. An aperture diaphragm is located between the second lens group and the third lens group or located in the third lens group. When varying power from the wide angle end to the telephoto end, the first lens group is fixed, the second lens group is moved from the object side to an image surface side, and at least one lens group among lens groups located closer to an image side than the aperture diaphragm is moved. The first lens group has at least four positive lens elements and at least two negative lens elements.SELECTED DRAWING: Figure 1 【課題】前玉径が小さく、光学系の全長を短縮しながら、色収差が良好に補正された小型で結像性能が高い変倍光学系及びそれを備えた撮像装置を提供すること。【解決手段】変倍光学系は、複数のレンズ素子で構成され、物体側から順に、正の屈折力を有する第１レンズ群と、負の屈折力を有する第２レンズ群と、正の屈折力を有する第３レンズ群と、少なくとも１つのレンズ群と、を有し、開口絞りは、第２レンズ群と第３レンズ群の間に位置するか、又は、第３レンズ群中に位置し、広角端から望遠端への変倍に際して、第１レンズ群は、固定であり、第２レンズ群は、物体側から像面側へ移動し、開口絞りよりも像側に位置するレンズ群のうち、少なくとも１つのレンズ群が移動し、第１レンズ群は、少なくとも４枚の正レンズ素子と、少なくとも２枚の負レンズ素子と、を有する。【選択図】図１