| 摘要 |
<p>PURPOSE:To prevent the generation of flare in the wide angle state and the telescopic state and to observe an excellent image by arranging a flare diaphragm in the respective groups composing an optical system. CONSTITUTION:A first flare diaphragm FS1 is provided between the first lens component L1 of a first group and an infrared cutting filter F1, a second flare diaphragm FS2 is provided on the image side of a second group (the image side of a fourth lens component L4) and a third flare diaphragm FS3 is provided on the most object side of a third group (the object side of a fifth lens component L5). Namely, the flare diaphragms FS1-FS3 are provided in whichever group. In such an endoscopic objective optical system, unwanted light made incident from the outside of a visual field in the wide angle state is removed by means of the flare diaphragms FS1, FS3 of the first and the third groups and unwanted light made incident from the outside of the visual field in the telescopic state is removed by means of the flare diaphragm FS2 of the second group.</p> |
