US5099268A — Technique for selecting lens aperture size for a …

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.

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

Technique for selecting lens aperture size for a fill flash exposure

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