Variable-power optical system and imaging device
US7630138B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 19, 2008 |
| Grant date | Dec 8, 2009 |
| Priority date | — |
| Expiry date | Mar 19, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/145113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A variable-power optical system includes, in order from an object side, first to fifth lens groups. The first and third lens groups are fixed at a time of varying magnification and at a time of focusing. The second, fourth and fifth lens groups are movable at the time of varying magnification. The first, third and fourth lens groups have positive refractive powers. The second and fifth lens groups have negative refractive powers. The fourth lens group has a focusing function. The following conditional expressions are satisfied.0.4<fw/f1<0.80.5<|f2/fw|<0.8where fw denotes a focal length of the whole system at an wide end, f1 denotes a focal length of the first lens group, and f2 denotes a focal length of the second lens group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.