US5099268A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Technique for selecting lens aperture size for a fill flash exposure
Assignee: Eastman Kodak Co
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Filing: 1990-09-20
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Granted: 1992-03-24
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Expires: 2010-09-20
Abstract
Abstract Apparatus, and an accompanying method, for use in a photographic camera for determining a lens aperture value for use during a fill flash exposure of a scene wherein the aperture value will impart a sufficient depth-of-field to a photographed image of the scene to capture both near and distant (background) subjects therein with pre-defined, typically ISO normal, exposures. Specifically, minimum and maximum aperture limit values are first determined from the permissible fastest and slowest shutter speeds that can be used to provide an ISO normal exposure of the distant subject. The fastest shutter speed is the fastest shutter speed to which a flash unit in use can be synchronized, while the slowest shutter speed is governed by the focal length of the lens in use. Given these maximum and minimum aperture limit values, the lens aperture to use for the fill flash exposure is determined as that which, based upon the distance of the near subject to the camera and a guide number of the flash unit, will provide an ISO normal exposure of the near subject and is equal to either the maximum or minimum aperture limit value or lies between these two limit values.
Inventors
- 👤 William R. O'Such
- 👤 Roger W. Wilson
- 👤 Richard B. Wheeler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:30
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/091; G03B7/097; G03B2206/00; G03B2206/004; G03B2207/00; G03B2207/005; G03B2217/00; G03B2217/005
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
208 words
Apparatus for capturing an image of a scene using a fill flash exposure, said scene having a subject with near and distant subject elements, said apparatus having a flash unit and an image sensing device wherein said image sensing device has a lens and a variable lens aperture associated therewith, said apparatus comprising: means for obtaining a value for lumination of said distant subject in the scene so as to form a distant subject light level and for obtaining a value for distance from said image sensing device to said near subject element so as to form a near subject distance; means, responsive to the distant subject light level and the near subject distance, for determining a value for said lens aperture for use during the fill flash exposure that will expose both said near and distant subject elements in said captured image with corresponding pre-defined levels of exposure, whereby said aperture value will impart a sufficient dept-of-field to sad captured image to satisfy a depth-of-field requirement in said scene defined by locations of said near and distant subject elements relative to said image sensing device; and means, coupled to said lens, for setting said lens to said determined aperture value for use during the fill flash exposure.
Claim 2
Dependent Claim
208 words
Apparatus for capturing an image of a scene using a fill flash exposure, said scene having a subject with near and distant subject elements, said apparatus having a flash unit and an image sensing device wherein said image sensing device has a lens and a variable lens aperture associated therewith, said apparatus comprising: means for obtaining a value for lumination of said distant subject in the scene so as to form a distant subject light level and for obtaining a value for distance from said image sensing device to said near subject element so as to form a near subject distance; means, responsive to the distant subject light level and the near subject distance, for determining a value for said lens aperture for use during the fill flash exposure that will expose both said near and distant subject elements in said captured image with corresponding pre-defined levels of exposure, whereby said aperture value will impart a sufficient dept-of-field to sad captured image to satisfy a depth-of-field requirement in said scene defined by locations of said near and distant subject elements relative to said image sensing device; and means, coupled to said lens, for setting said lens to said determined aperture value for use during the fill flash exposure.
Claim 3
Dependent Claim
87 words
The apparatus in claim 1 wherein said lens aperture value determining means comprises: first means, responsive to said distant subject light level and slowest and fastest shutter speed limit values, for determining minimum and maximum aperture values to provide the pre-defined exposure level for said distant subject element; and second means, responsive to said first determining means and said near subject distance, for determining the lens aperture value such that said lens aperture value lies between or is equal to either said minimum and maximum aperture values.
Claim 4
Dependent Claim
16 words
The apparatus in claim 2 wherein said pre-defined levels of exposure are ISO normal exposure levels.
Claim 5
Dependent Claim
16 words
The apparatus in claim 3 wherein said image sensing device is a photographic or electronic camera.
Claim 6
Dependent Claim
38 words
The apparatus in claim 4 wherein said first determining means comprises means for calculating said minimum and maximum aperture values as functions of said distant subject light level and respectively said fastest shutter speed or slowest shutter speed.
Claim 7
Dependent Claim
28 words
The apparatus in claim 5 wherein said fastest shutter speed is a fastest shutter speed to which said flash unit can be synchronized to said image sensing device.
Claim 8
Dependent Claim
31 words
The apparatus in claim 6 wherein said first determining means further comprises means for ascertaining said slowest shutter speed in response to a value of a focal length of said lens.
Claim 9
Dependent Claim
42 words
The apparatus in claim 7 wherein said slowest shutter speed ascertaining means comprises means for generating said slowest shutter speed as a product of a focal length factor multiplied by a reciprocal of the value of the focal length of the lens.
Claim 10
Dependent Claim
33 words
The apparatus in claim 8 wherein said obtaining means comprise means for measuring said distant subject light level and said near subject distance in said scene so as to form measured values thereof.
Claim 11
Dependent Claim
38 words
The apparatus in claim 4 wherein said wherein said second determining means comprises means for calculating said lens aperture value as a value of a guide number associated with said flash unit divided by said near subject distance.
Claim 12
Dependent Claim
26 words
The apparatus in claim 10 wherein said obtaining means comprise means for measuring said distant subject light level and said near subject distance in said scene.
Claim 13
Dependent Claim
203 words
In apparatus for capturing an image of a scene using a fill flash exposure, said scene having a subject with near and distant subject elements, said apparatus having a flash unit and an image sensing device wherein said image sensing device has a lens and a variable lens aperture associated therewith, a method comprising the steps of: obtaining a value for lumination of said distant subject in the scene so as to form a distant subject light level and for obtaining a value for distance from said image sensing device to said near subject element so as to form a near subject distance; determining, in response to the distant subject light level and the near subject distance, a value for said lens aperture for use during the fill flash exposure that will expose both said near and distant subject elements in said captured image with corresponding pre-defined levels of exposure, whereby said aperture value will impart a sufficient depth-of-field to said captured image to satisfy a depth-of-field requirement in said scene defined by locations of said near and distant subject elements relative to said image sensing device; and setting said lens to said determined aperture value for use during the fill flash exposure.
Claim 14
Dependent Claim
203 words
In apparatus for capturing an image of a scene using a fill flash exposure, said scene having a subject with near and distant subject elements, said apparatus having a flash unit and an image sensing device wherein said image sensing device has a lens and a variable lens aperture associated therewith, a method comprising the steps of: obtaining a value for lumination of said distant subject in the scene so as to form a distant subject light level and for obtaining a value for distance from said image sensing device to said near subject element so as to form a near subject distance; determining, in response to the distant subject light level and the near subject distance, a value for said lens aperture for use during the fill flash exposure that will expose both said near and distant subject elements in said captured image with corresponding pre-defined levels of exposure, whereby said aperture value will impart a sufficient depth-of-field to said captured image to satisfy a depth-of-field requirement in said scene defined by locations of said near and distant subject elements relative to said image sensing device; and setting said lens to said determined aperture value for use during the fill flash exposure.
Claim 15
Dependent Claim
88 words
The method in claim 12 wherein said lens aperture value determining step comprises the steps of: first determining, in response to said distant subject light level and slowest and fastest shutter speed limit values, minimum and maximum aperture values to provide the pre-defined exposure level for said distant subject element; and second determining, in response to said first determining step and said near subject distance, the lens aperture value such that said lens aperture value lies between or is equal to either said minimum and maximum aperture values.
Claim 16
Dependent Claim
16 words
The method in claim 13 wherein said pre-defined levels of exposure are ISO normal exposure levels.
Claim 17
Dependent Claim
16 words
The method in claim 14 wherein said image sensing device is a photographic or electronic camera.
Claim 18
Dependent Claim
39 words
The method in claim 15 wherein said first determining step comprises the step of calculating said minimum and maximum aperture values as functions of said distant subject light level and respectively said fastest shutter speed or slowest shutter speed.
Claim 19
Dependent Claim
28 words
The method in claim 16 wherein said fastest shutter speed is a fastest shutter speed to which said flash unit can be synchronized to said image sensing device.
Claim 20
Dependent Claim
32 words
The method in claim 17 wherein said first determining step further comprises the step of ascertaining said slowest shutter speed in response to a value of a focal length of said lens.
Claim 21
Dependent Claim
43 words
The method in claim 18 wherein said slowest shutter speed ascertaining step comprises the step of generating said slowest shutter speed as a product of a focal length factor multiplied by a reciprocal of the value of the focal length of the lens.
Claim 22
Dependent Claim
34 words
The method in claim 19 wherein said obtaining step comprises the step of measuring said distant subject light level and said near subject distance in said scene so as to form measured values thereof.
Claim 23
Dependent Claim
37 words
The method in claim 15 wherein said second determining step comprises the step of calculating said lens aperture value as a value of a guide number associated with said flash unit divided by said near subject distance.
Claim 24
Dependent Claim
34 words
The method in claim 21 wherein said obtaining step comprises the step of measuring said distant subject light level and said near subject distance in said scene so as to form measured values thereof.
References Cited (Backward Citations)
US3888580A
Cited
US3843255A
Cited
US3917395A
Cited
US4103307A
Cited
US4101216A
Cited
US4182560A
Cited
US4092067A
Cited
US4100424A
Cited
US4154523A
Cited
US4309089A
Cited
US4168120A
Cited
US4339517A
Cited
US4279505A
Cited
US4345825A
Cited
US4429969A
Cited
US4598986A
Cited
JPS61145971A
Cited
EP0189981A1
Cited
US4769666A
Cited
DE3637742A1
Cited
US4785323A
Cited
US4801964A
Cited
US4812872A
Cited
US4772910A
Cited
JPH01222209A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-03-24 | 1995-09-23 | 1996-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-24 | 1999-09-23 | 2000-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-24 | 2003-09-23 | 2004-03-24 | $7700.00 | Window Closed / Lapsed |