Two element optical system, a camera using it and method of making the camera
AssigneeEastman Kodak Company
InventorAlan E. Lewis
Life of this patent
Estimating the term…
Abstract
An optical system comprising two lens elements one of which is biaspheric, the optical system is suitable for use in photographic devices such as single-use cameras having curved image planes. This optical system can operate at low F-numbers while maintaining an excellent performance.
Claims24
An optical system for use in a low-cost camera having a photosensitive material with an image surface curved toward said optical system, said optical system comprising only two single lens components and an aperture stop located therebetween, wherein one of said lens components is biaspheric, said optical system forming a curved image corresponding substantially to the curved image surface of the camera through a full field angle .theta. of at least 62.5 degrees, and wherein said optical system is not sensitive to aspheric surface decenter of .+-.0.025 mm of said biaspheric lens component, so that the heterochromatic MTF values of the optical system are
- MTF>58,
- where MTF represents sagittal and tangential MTF values at the spatial frequency of 12.5 lines/mm, from zero to about 70% field of view.
An optical system having an image surface curved toward the optical system, said optical system comprising:
- (i) two single non-identical lens elements, one of which is biaspheric, and wherein the ratio of the focal lengths of the two lens elements fall within the range:
- ##EQU1## or within the range ##EQU2## where f1 is the focal length of a front lens element and f2 is the focal length of a rear lens element;
- and
- (ii) an aperture stop, said aperture stop being positioned between said two lens elements, each of said lens elements being a meniscus lens element concave to said aperture stop.
An optical system having an image surface curved toward the optical system, said optical system being characterized by good aberration correction over a full field angle of at least 62.5 degrees and an F/number below F/11, said optical system comprising two single non-identical lens elements, one of which is biaspheric, and an aperture stop, said aperture stop being positioned between said two lens elements, each of said lens elements being a meniscus lens element concave to the aperture stop;
- and wherein said optical system has a nominal average heterochromatic MTF value and said optical system is not sensitive to aspheric surface decenter of .+-.0.025 mm of the biaspheric lens element, so that the average heterochromatic MTF value of the optical system with a decentered aspheric surface is 7 or fewer percentage points smaller than the nominal average heterochromatic MTF value,
- where the average heterochromatic MTF value=(Sagittal Value+Tangential Value)/2, and is measured at 71% field at 12.5 lines per mm.
A method of making a single-use camera from previously used camera parts, said method comprising the steps of:
- (A) providing a camera body having a film cassette chamber;
- (B) supporting in said camera body previously used single-use camera parts including (i) a viewfinder, (ii) a shutter mechanism, and (iii) an optical system desensitized for biaspheric sensitivity to aspheric surface decenter of .vertline.0.025.vertline.mm, said optical system including only two lens elements, at least one of said lens elements being biaspheric and each of said lens elements having an index of refraction of at least 1.45, and
- (C) loading an unexposed roll of film into the film cassette chamber of the camera body.
A single-use camera made from previously used camera parts comprising:
- a camera body having a film cassette chamber, said camera body supporting previously used camera parts including an optical system desensitized for biaspheric sensitivity to aspheric surface decenter of .vertline.0.025.vertline.mm, said optical system being comprised of only two lens elements, one of said lens elements being biaspheric and a shutter located between said lens elements, wherein said optical system being adapted for imaging on a curved film plane;
- a shutter mechanism, and a viewfinder;
- and
- an unexposed roll of film mounted in the film cassette chamber of the camera body.
Dependencies are inferred from the claim text.