Still video camera and device for adjusting control data for amount of strobe emission

• US 5,438,367 A
• Filed: 04/26/1994
• Issued: 08/01/1995
• Est. Priority Date: 04/26/1993
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Yamamoto, Masanaga, Soga, Takashi, Kaneko, Kiyotaka, Arai, Minoru
• Primary Examiner(s): GARBER, WENDY RAE
• Application Number:
  US08/233,346
• Time in Patent Office: 462 Days
• Field of Search: 348/370, 348/371, 348/216
• US Class Current: 348/371
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means

Abstract

An amount-of-light-emission control data for controlling the amount of light-emission is corrected so that the amount of strobe light-emission becomes proper. In the adjustment process after manufacturing a digital still camera, a subject is placed in a predetermined position, and is photographed by determining a predetermined guide number GN. A guide number GN corresponding to the amount of light-emission of a strobe 45 is calculated from a video signal obtained by the photography. The predetermined actual guide number GN and the guide number GN corresponding to the actual amount of light-emission are compared with each other, to correct the value of control data for determining the amount of light-emission so that there is no difference therebetween. The corrected or updated value of control data in which the predetermined updated corrected guide number GN and the guide number GN corresponding to the actual amount of light-emission are approximately equal to each other is stored in a memory 6. At the time of actual photography, the updated corrected value of control data is read out from the memory 6 in conformity with the updated corrected guide number GN, and the data read out is applied to an amount-of-light-emission control circuit 30, so that a strobe flash is fired.

Claims

1. A device for adjusting control data for determining the amount of strobe light-emission in a still video camera having a strobe flash device, comprising:

photographing means for photographing a subject to output a video signal representing an image of said subject;

guide number calculating means for calculating a guide number as a function of the distance to said subject from said photographing means and an F-number of said photographing means;

storing means for storing an initial value of control data for determining the amount of strobe light-emission of said strobe flash device corresponding to said guide number;

strobe light-emission control means for reading out from said storing means said initial value of said control data and firing said strobe flash device to emit an amount of light corresponding to said guide number;

strobe-light-emission detecting means for detecting the actual amount of light emitted by said strobe flash device under control of said strobe light-emission control means;

said actual amount of light emitted by said strobe flash device and said amount determined as corresponding to said guide number having an allowable range of difference therebetween;

judging means for judging whether or not said allowable range of difference has been exceeded; and

correcting means for updating said initial value of control data in said storing means in response to a judgment by said judging means that said allowable range of difference has been exceeded to bring said difference within said allowable range.

2. The device for adjusting control data as set forth in claim 1, wherein said correcting means includes incremented control means for incrementally and repeatedly adjusting said initial value of control data in said storing means and causing repeated firing of said strobe flash device until said judging means determines that said allowable range of difference has been satisfied.

3. A still video camera comprising:

rangefinding means for measuring the distance to a subject to be photographed,

guide number calculating means for calculating a guide number as a function of the distance to the subject measured by said rangefinding means and an F-number of said camera;

a strobe flash device for projecting strobe light on the subject;

storing means for storing values of control data corresponding to said guide numbers for determining the desired amount of strobe light-emission including correcting means for updating such stored values so that the actual amounts of strobe light-emission correspond to the desired amounts represented by said guide numbers to within an allowable range;

strobe light-emission control means for reading from said storing means said corrected values of control data to control the strobe flashing by said strobe flash device;

photographing means for photographing the subject under the strobe flashing by said strobe flash device to output a video signal representing an image of the subject; and

recording means for recording the video signal outputted from said photographing means on a recording medium.

4. A method of adjusting the value of control data for determining the amount of strobe light-emission in a still video camera having a strobe flash device, comprising the steps of:

storing an initial value of said control data for controlling the amount of strobe light-emission of said strobe flash device in correspondence to a guide number;

calculating the guide number as a function of the distance to a subject to be photographed and an F-number of said video camera;

reading out said stored initial value of said control data corresponding to said calculated guide number to fire a strobe flash for generating an amount of strobe light-emission corresponding to said initial value of control data;

photographing said subject under the strobe flashing to obtain a video signal representing an image of the subject;

detecting the amount of strobe light-emission on the basis of the obtained video signal;

judging whether or not the difference between the detected amount of strobe light-emission and the amount of strobe light-emission represented by the calculated guide number is within an allowable range; and

correcting said initial value of said control data so that said difference between said amounts of strobe light-emission is within said allowable range.

5. The method of adjusting the value of control data for determining the amount of strobe light-emission in a still video camera as defined in claim 4, wherein:

said storing an initial value of said control data includes plural initial values for a like plurality of guide numbers;

said guide numbers are calculated from a respective plurality of distances to a subject to be photographed; and

each of said initial values of said control data are corrected so that the differences between said detected amounts of strobe-light emission at each of said plurality of distances and the amount of light represented by a respective calculated guide number is within said allowable range.

6. The method of adjusting the value of control data for determining the amount of strobe light-emission in a still video camera according to claim 5, further comprising the step of

repeating the processing for strobe flashing, the processing for detecting the amount of strobe light-emission, the processing for judgment, and the processing for correction until it is judged that said difference between the amounts of strobe light-emission is within said allowable range for said values of control data, respectively, for said plurality of distances.

7. The method of adjusting the value of control data for determininq the amount of strobe light-emission in a still video camera according to claim 4, further comprising the step of

repeating the processing for strobe flashing, the processing for detecting the amount of strobe light-emission, the processing for judgment, and the processing for correction until it is judged that said difference between the amounts of strobe light-emission is within said allowable range.

8. A method of operating and controlling the amount of strobe light-emission in a still video camera having a strobe flash device, comprising the steps of:

measuring the distance to a subject to be photographed;

calculating a guide number as a function of the measured distance to said subject and an F-number of said camera as an initial representation of a desired amount of light-emission;

generating and storing an initial value of said control data corresponding to said guide number;

firing said strobe flash device and determining the actual amount of light emitted in correspondence to said initial value of control data;

comparing said actual value to said desired amount of light-emission and correcting said initial value of said control data until said comparison is within an allowable tolerance range;

storing said corrected value of control data;

reading from said storing means the corrected value of control data for determininq the desired amount of strobe light-emission corresponding to the calculated guide number;

firing the strobe flash by said strobe flash device on the basis of the corrected value of control data;

photographing said subject under the strobe flashing to obtain a video signal representing an image of the subject; and

recording the obtained video signal on a recording medium.

9. The method of adjusting the value of control data for determining the amount of strobe light-emission in a still video camera as defined in claim 8, wherein:

said storing an initial value of said control data includes plural initial values for a like plurality of guide numbers;

said guide numbers are calculated from a respective plurality of distances to a subject to be photographed; and

each of said initial values of said control data are corrected so that the differences between said detected amounts of strobe-light emission at each of said plurality of distances and the amount of light represented by a respective calculated guide number is within said allowable range.

10. The device for adjusting control data as set forth in claim 9, wherein said correcting means includes incremented control means for incrementally and repeatedly adjusting said initial value of control data in said storing means and causing repeated firing of said strobe flash device until said judging means determines that said allowable range of difference has been satisfied for said values of control data, respectively, for said plurality of distances.