Zoom lens
US6028716A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 15, 1997 |
| Grant date | Feb 22, 2000 |
| Priority date | — |
| Expiry date | Jul 15, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144507
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens is disclosed, comprising, from front to rear, a first lens group of negative refractive power, a second lens group of positive refractive power and a third lens group of negative power, zooming being performed by varying a separation between each adjacent two of the lens groups, wherein for an object at infinity, an aspheric sphere of such shape that a negative refractive power gets progressively stronger toward the margin is applied to a lens surface of negative refracting power concave toward the object side which satisfies the following condition: EQU Hiw>.vertline.Hbiw.vertline. EQU Hit>.vertline.Hbit.vertline. where Hiw (Hiw>0) and Hit (Hit>0) are the heights of incidence for the wide-angle end and the telephoto end of the on-axial ray of light on the i-th surface, respectively, and Hbiw and Hbit are the heights of incidence for the wide-angle end and the telephoto end of the off-axial principal ray of light from the maximum angle of field on the i-th surface, respectively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.