Browse Prior Art Database

WIDE ANGLE ADD LENS REDUCTION SYSTEMS

IP.com Disclosure Number: IPCOM000024064D
Original Publication Date: 1979-Aug-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 288K

Publishing Venue

Xerox Disclosure Journal

Abstract

The current state of the art of imaging systems provides two general methods of varying image size. One is to vary the overall object to image distance and move the (fixed focal length) lens to obtain sharp imagery. The second is to keep the overall object to image distance fixed and vary the focal length (and position) of the lens to provide sharp imagery.

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XEROX DISCLOSURE JOURNAL

WIDE ANGLE ADD LENS REDUCTION SYSTEMS
Vance Carpenter

S1~P

/g

ADD LENS

Proposed Classification
U.S. Cl. 350/184

mt. CL G02b 15/00

The current state of the art of imaging systems provides two general methods of varying image size. One is to vary the overall object to image distance and move the (fixed focal length) lens to obtain sharp imagery. The second is to keep the overall object to image distance fixed and vary the focal length (and position) of the lens to provide sharp imagery.

For the variable focal length method of obtaining varying image size, there are two

methods of changing the focal length. One is to move the elements within the lens such that the focal length is changed while still maintaining acceptable image quality. This will provide a continuously variable change in focal length thus allowing a continuous range of varying image sizes. The second is to introduce

another element on the lens (a so~called add lens) that will provide a new combination of elements having an appropriate focal length. In this case, generally speaking, a different add lens is required for each different focal length; and hence, a different add lens is required for each image size desired,

Another problem with the add lens technique is that, since the add lenses are external to the main lens, they tend to be large. This large size results in these lenses being more expensive than is desired and in a cumbersome mechanism to position them in use, Examination of lenses i...