The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 19, 1995
Filed:
Feb. 23, 1994
Nikon corporation, Tokyo, JP;
Abstract
An inverse telescopic wide angle lens comprises a diaphragm; a front lens group of an integral positive or negative refractive power, positioned in the object side in front of the diaphragm and having a first lens group of a negative refractive power including a negative lens of which an image-side air-contacting surface is formed as an aspherical surface concave to the image side, and a second lens group of a positive refractive power positioned between the first lens group and the diaphragm; and a rear lens group of an integral positive refractive power, positioned behind the diaphragm and having plural lenses. The negative lens in the first lens group is so constructed that the absolute value of the refractive power of the concave surface on the optical axis is larger than that of the refractive power of the surface at the object side on the optical axis, that the curvature of the concave surface decreases monotonously with the distance from the optical axis, and that the form of the concave surface of the negative lens at the image side satisfies a particular condition. The effective diameter of the lens closest to the object in the first lens group is so constructed as to satisfy a particular condition.