Zoom lens
US8184379B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 20, 2011 |
| Grant date | May 22, 2012 |
| Priority date | — |
| Expiry date | Jan 20, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/1425
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens includes sequentially from an object side a first lens group having a negative refractive power; a diaphragm; and a second lens group having a positive refractive power. Zoom from a wide angle edge to a telephoto edge is performed by displacement of the second lens group along an optical axis, toward the object side. Correction of imaging plane variation accompanying zoom, is performed by displacement of the first lens group along the optical axis. The second lens group includes a positive first lens disposed farthest on the object side and having at least one aspheric surface, and a cemented lens that includes a negative lens, a positive lens, and a negative lens. Furthermore, a first condition υd2p>75 is satisfied, υd2p being the Abbe number for a d-line in the positive lens included in the cemented lens of the second lens group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.