US3762298A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure compensation arrangement for a variably focused polarizing system
Assignee: Polaroid Corp
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Filing: 1972-04-24
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Granted: 1973-10-02
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Expires: 1992-04-24
Abstract
Abstract A variable exposure compensation arrangement for use with a photographic camera incorporating a follow-focus exposure control system. The compensation arrangement is employed when the camera is used in conjunction with two linear polarizers for alleviating specular reflections. In order to compensate for the absorption of light within each polarizer, the compensation arrangement induces the follow-focus system to permit more light to enter the camera, thereby counterbalancing the decrease in light by the polarizers. The compensation arrangement includes a housing attached to the camera in an overlying relationship with the objective lens, and a movable lens means mounted within the housing.
Inventors
- 👤 B Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:19
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/16; G03B3/00; G03B3/02; G03B13/00; G03B13/18
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
152 words
An exposure compensation apparatus for use with a photographic camera having an objective lens for focusing an image to be photographed, a shutter, a source of artificial illumination, and incorporating a follow-focus exposure control system, said exposure compensation apparatus comprising: a housing, attachable to a portion of said photographic camera in overlying relationship with said objective lens of said photographic camera; light reducing means for reducing the level of light entering said objective lens of said camera, said light reducing means being positioned within said housing in covering relationship in front of said objective lens of said camera; and lens means, movably mounted within said housing in optical covering relationship with said objective lens of said photographic camera, for producing an artificial focus condition within said objective lens and said follow-focus exposure control system for causing said follow-focus exposure control system to compensate for said reduced light level entering said objective lens.
Claim 2
Dependent Claim
152 words
An exposure compensation apparatus for use with a photographic camera having an objective lens for focusing an image to be photographed, a shutter, a source of artificial illumination, and incorporating a follow-focus exposure control system, said exposure compensation apparatus comprising: a housing, attachable to a portion of said photographic camera in overlying relationship with said objective lens of said photographic camera; light reducing means for reducing the level of light entering said objective lens of said camera, said light reducing means being positioned within said housing in covering relationship in front of said objective lens of said camera; and lens means, movably mounted within said housing in optical covering relationship with said objective lens of said photographic camera, for producing an artificial focus condition within said objective lens and said follow-focus exposure control system for causing said follow-focus exposure control system to compensate for said reduced light level entering said objective lens.
Claim 3
Dependent Claim
32 words
The exposure compensation apparatus according to claim 1 in which said exposure compensation apparatus further includes means for varying said lens means with respect to said objective lens of said photographic camera.
Claim 4
Dependent Claim
28 words
The exposure compensation apparatus according to claim 1 in which said light reducing means for reducing said level of light entering said objective lens is a polarizing member.
Claim 5
Dependent Claim
63 words
The exposure compensation apparatus according to claim 3 in which a polarizing member is positioned in covering relationship with said objective lens and another polarizing member is positioned in front of said source of artificial illumination, said exposure compensation apparatus being operative to induce said follow-focus exposure control system to compensate for lower light levels due to light absorption within said polarizing members.
Claim 6
Dependent Claim
72 words
The exposure compensation apparatus according to claim 3 in which said exposure compensation apparatus includes a variable focal length doublet lens, said doublet lens being operative to form a virtual image of an object to be photographed at a distance approximately twice the object distance, said follow-focus exposure control system thereby being induced to allow more light to enter said camera than is necessary for an object placed at said objective distance.
Claim 7
Dependent Claim
85 words
The exposure compensation apparatus according to claim 5 in which said variable focal length doublet lens includes a positivE converging lens element and a negative diverging lens element, said positive converging lens element being mounted within said housing a given distance from said objective lens and said negative diverging lens element being movably mounted within said housing, said negative diverging lens element being movable with respect to said positive converging lens element in response to movement of said objective lens when said camera is focused.
Claim 8
Dependent Claim
85 words
The exposure compensation apparatus according to claim 5 in which said variable focal length doublet lens includes a negative diverging lens element and a positive converging lens element, said negative diverging lens element being mounted within said housing a given distance from said objective lens and said positive converging lens element being movably mounted within said housing, said positive converging lens element being movable with respect to said negative diverging lens element in response to movement of said objective lens when said camera is focused.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-01 | 1977-04-02 | 1977-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-01 | 1981-04-02 | 1981-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-01 | 1985-04-02 | 1985-10-02 | $7700.00 | Window Closed / Lapsed |