Back to results
US 8,576,501 B2Granted
Wide-angle optical system, image pickup lens device, monitor camera, and digital apparatus
AssigneeKonica Minolta Opto, Inc.
InventorsKeiji Matsusaka, Toru Nakatani
Life of this patent
Estimating the term…
Abstract
A wide-angle optical system comprises a front lens group (11), and a rear lens group (12), with an aperture stop (13) interposed between. The front lens group (11) includes at least two negative lenses (111, 112) and at least one positive lens (113). At least one of the positive lenses included in the front lens group (11) has at least one aspherical surface. The front lens group (11) satisfies the conditional expression vdp<29 where vdp is the minimum value of the Abbe number of the positive lens(es) included in the front lens group (11).
Claims20
A wide-angle optical system comprising:
- a front lens group;
- a rear lens group;
- and
- an aperture stop arranged between the front lens group and the rear lens group,
- wherein the front lens group includes at least two negative lenses and at least one positive lens,
- at least one of a positive lens or positive lenses in the front lens group includes at least one aspheric surface, and
- the front lens group satisfies the following conditional expression:
- vdp <29,
- where vdp is a minimum Abbe number of the positive lens or positive lenses in the front lens group,
- wherein the wide-angle optical system satisfies the following conditional expression:
- Y′/TL >0.1,
- where Y′ is a maximum image height, and
- TL is a distance along an optical axis from a surface vertex on a lens surface arranged at a closest position to an object, to an image plane, where a back focal length is measured in an air conversion length, and
- wherein the at least one positive lens satisfies the following conditional expression:
- |Hp|/Rp>0.65,
- where Hp is a height (a distance from an optical axis) of a principal ray of a light flux corresponding to a maximum image height on an object-side surface of the at least one positive lens, and
- Rp is a maximum effective radius of the object-side surface of the at least one positive lens.
14 more elements
A wide-angle optical system comprising:
- a front lens group;
- a rear lens group;
- and
- an aperture stop arranged between the front lens group and the rear lens group,
- wherein the front lens group includes at least two negative lenses and at least one positive lens,
- at least one of a positive lens or positive lenses in the front lens group includes at least one aspheric surface, and
- the front lens group satisfies the following conditional expression:
- vdp<29
- where vdp is a minimum Abbe number of the positive lens or positive lenses in the front lens group, and
- wherein a lens arranged at a closest position to an object is a glass lens and satisfies the following conditional expression:
- DA1<0.35
- where DA1 is a value representing acid-resistance which is obtained by putting powder of a glass material of the lens arranged at the closest position to the object into nitric acid solution with a concentration of 0.01 mol/l, heating the nitric acid solution in a boiling bath, and measuring a reduced mass (%) of the powder of the glass material as the value representing acid-resistance.
9 more elements
A wide-angle optical system comprising:
- a front lens group;
- a rear lens group;
- and
- an aperture stop arranged between the front lens group and the rear lens group,
- wherein the front lens group includes at least two negative lenses and at least one positive lens,
- at least one of a positive lens or positive lenses in the front lens group includes at least one aspheric surface, and
- the front lens group satisfies the following conditional expression:
- vdp<29,
- where vdp is a minimum Abbe number of the positive lens or positive lenses in the front lens group,
- wherein the wide-angle optical system satisfies the following conditional expression:
- Y′/TL >0.1,
- where Y′ is a maximum image height, and
- TL is a distance along an optical axis from a surface vertex on a lens surface arranged at a closest position to an object, to an image plane, where a back focal length is measured in an air conversion length, and
- wherein a lens arranged at a closest position to an object is a negative lens which satisfies the following conditional expression:
- 33<vd1<47,
- where vd1 is an Abbe number of the lens arranged at the closest position to the object.
13 more elements
Dependencies are inferred from the claim text.