| 发明名称 | Fixed focus lens | ||
| 摘要 | A fixed focus lens comprising, sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. The first lens group includes an aperture stop. The second lens group is configured by a single lens element. During focusing, the second lens group moves along an optical axis and the first lens group and the third lens group are fixed with respect to an imaging plane. | ||
| 申请公布号 | US8908297(B2) | 申请公布日期 | 2014.12.09 |
| 申请号 | US201314063691 | 申请日期 | 2013.10.25 |
| 申请人 | Tamron Co., Ltd. | 发明人 | Adachi Nobuyuki;Obikane Yasuhiko;Sakai Takahiko |
| 分类号 | G02B9/14;G02B13/00;G02B9/12;G02B9/62;G02B9/64 | 主分类号 | G02B9/14 |
| 代理机构 | Foley & Lardner LLP | 代理人 | Foley & Lardner LLP |
| 主权项 | 1. A fixed focus lens comprising, sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power, wherein the first lens group includes an aperture stop and imaging plane side of the aperture stop is disposed adjacent to a negative lens, the second lens group is configured by a single lens element, during focusing, the second lens group moves along an optical axis and the first lens group and the third lens group are fixed with respect to an imaging plane, and a conditional expression (2) 0.4<F3/F<1.8 is satisfied, where F3 is a focal length of the third lens group and F is a focal length of the entire optical system. | ||
| 地址 | Saitama-shi JP | ||