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:
Nov. 04, 2014
Filed:
Aug. 20, 2012
Applicants:
J. Brian Caldwell, Petersburg, VA (US);
Wilfried Bittner, Tsuen Wan, HK;
Inventors:
J. Brian Caldwell, Petersburg, VA (US);
Wilfried Bittner, Tsuen Wan, HK;
Assignee:
Caldwell Photographic, Inc., Petersburg, VA (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G03B 17/00 (2006.01); G02B 9/34 (2006.01); G02B 15/177 (2006.01); G02B 13/18 (2006.01);
U.S. Cl.
CPC ...
G02B 15/177 (2013.01); G02B 13/18 (2013.01);
Abstract
An optical attachment configured to be operably attached to the image side of an objective lens to reduce the focal length and focal ratio of the objective lens. The focal-reducing attachment includes four lens elements and has a magnification of between 0.5 and 1. The focal-reducing lens can work with objective lenses having relatively large working distances for a large format size as well as with cameras having a smaller format size and relatively small permissible working distance.