Inner focus lens system and image pickup apparatus using the same
US8654448B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 5, 2012 |
| Grant date | Feb 18, 2014 |
| Priority date | — |
| Expiry date | Dec 5, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/143103
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An inner focus lens system includes from the object side, a first lens unit having a positive refractive power, an aperture stop, a second lens unit having a positive refractive power, and a third lens unit. The first lens unit includes a plurality of negative lenses and at least one positive lens, the lens located closest to the object side is a negative lens. The second lens unit includes at least one negative lens and at least one positive lens, and moves toward the object side for focusing from an infinite object distance to a close object distance such that the distance between the second lens unit and the aperture stop decreases and that the distance between the second lens unit and the third lens unit increases. The lens system satisfies the following conditions: 1<f1/f 14 (1), and 0.8<f23/f2<3 (2).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.