Camera

• US 20030063211A1
• Filed: 09/26/2002
• Published: 04/03/2003
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Maeda, Toshiaki, Ohta, Tadashi, Watanabe, Toshimi, Hibino, Hideo
• Granted Patent: US 7,184,090 B2
• Time in Patent Office: Days
• US Class Current: 348/345
• CPC Class Codes: H04N 23/651 for reducing power consumption by affecting camera operations, e.g. sleep mode, hibernation mode or power off of selective parts of the camera
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method
• CPC Class Codes: H04N 25/615 involving a transfer function modelling the optical system, e.g. optical transfer function [OTF], phase transfer function [PhTF] or modulation transfer function [MTF]

Abstract

A camera includes: an image-capturing element that captures a subject image through a photographic lens; an evaluation value calculation unit that calculates a focus evaluation value based upon an image-capturing signal output from the image-capturing element; a focusing operation unit that performs a focusing operation at the photographic lens based upon the focus evaluation value; a decision-making unit that makes a decision as to whether or not a predetermined length of time has elapsed following an end of the focusing operation; a restart unit that engages the focusing operation unit in a focusing operation if the decision-making unit decides that the predetermined length of time has elapsed; and a time adjustment unit that changes the predetermined length of time.

Claims

1. A camera comprising:

an image-capturing element that captures a subject image through a photographic lens;

an evaluation value calculation unit that calculates a focus evaluation value based upon an image-capturing signal output from the image-capturing element;

a focusing operation unit that performs a focusing operation at the photographic lens based upon the focus evaluation value;

a decision-making unit that makes a decision as to whether or not a predetermined length of time has elapsed following an end of the focusing operation;

a restart unit that engages the focusing operation unit in a focusing operation if the decision-making unit decides that the predetermined length of time has elapsed; and

a time adjustment unit that changes the predetermined length of time.

2. A camera according to claim 1, further comprising:

a determining unit that determines a time changing condition in conformance to which the predetermined length of time is changed by the time adjustment unit, wherein;

the time adjustment unit changes the predetermined length of time in conformance to the time changing condition determined by the determining unit.

3. A camera according to claim 2, further comprising:

an evaluation value detection unit that detects whether or not a focus evaluation value calculated after a focusing operation end manifests a change by an extent larger than a predetermined value relative to a focus evaluation value obtained at the focus operation end, wherein;

the restart unit enables the focusing operation unit in the focusing operation either when the decision-making unit decides that the predetermined length of time has elapsed or when the evaluation value detection unit detects the change by the extent larger than the predetermined value, whichever occurs first.

6. A camera according to claim 2, further comprising:

a timer that starts a time count upon completion of an initial focusing operation, wherein;

the determining unit determines the time changing condition so as to lengthen the predetermined length of time after a specific time count is counted at the timer compared to the predetermined length of time before the specific time count is counted at the timer.

7. A camera according to claim 2, wherein:

the determining unit determines the time changing condition so as to set the predetermined length of time in correspondence to a photographing condition or a camera state.

8. A camera according to claim 7, wherein:

the photographing condition is a focal length of the photographic lens; and

the determining unit determines the time changing condition so as to lengthen the predetermined length of time as the focal length increases.

9. A camera according to claim 7, wherein:

the photographing condition includes a first photographing mode suited for photographing a subject that moves slightly or almost not at all and a second photographing mode suited for photographing a subject that moves faster than the subject in the first photographing mode; and

the determining unit determines the time changing condition so as to shorten the predetermined length of time in the second photographing mode compared to the predetermined length of time set in the first photographing mode.

10. A camera according to claim 9, wherein:

the first photographing mode includes at least one of a normal photographing mode, a distant view photographing mode, a portrait photographing mode, a close-up photographing mode and a night photographing mode and the second photographing mode includes at least a sports photographing mode.

11. A camera according to claim 7, further comprising:

an aperture that is operated to adjust a quantity of subject light entering the image-capturing element, wherein;

an aperture value set at the aperture constitutes the photographing condition; and

the determining unit determines the time changing condition so as to lengthen the predetermined length of time as the aperture value increases.

12. A camera according to claim 7, further comprising:

a photometering unit that detects a brightness of a predetermined area of the subject, wherein;

the brightness detected by the photometering unit constitutes the photographing condition; and

the determining unit determines the time changing condition so as to lengthen the predetermined length of time as the brightness becomes lower.

13. A camera according to claim 7, wherein:

the image-capturing element includes a plurality of pixels;

a number of recording pixels to be used for recording in data of the image captured by the image-capturing element can be varied;

the number of recording pixels constitutes the photographing condition; and

the determining unit determines the time changing condition so as to lengthen the predetermined length of time as the number of recording pixels becomes smaller.

14. A camera in according to claim 7, further comprising:

a full-aperture F value detection unit that detects a full-aperture F value of the photographic lens constituting the photographing condition, wherein;

the determining unit determines the time changing condition so as to lengthen the predetermined length of time as a larger full-aperture F value is detected.

15. A camera according to claim 7, further comprising:

a voltage detection unit that detects a voltage of a camera drive battery constituting the camera state, wherein;

the determining unit determines the time changing condition so as to lengthen the predetermined length of time as the voltage detected by the voltage detection unit becomes lower.

43. A camera according to claim 1, further comprising:

a drive unit that moves the photographic lens along an optical axis;

a storage unit that individually stores a plurality of focus evaluation values calculated by the evaluation value calculation unit while the photographic lens is moved by the drive unit and lens positions assumed by the photographing lens when the plurality of focus evaluation values are calculated; and

a distance setting unit that sets a distance to be traveled by the photographic lens for a restart of the focusing operation based upon the focus evaluation values and the lens positions stored in the storage unit and the focus evaluation value calculated at the restart.

44. A camera according to claim 43, wherein:

the distance setting unit sets the distance to a value representing a distance between a first lens position corresponding to a focus evaluation value substantially equal to the focus evaluation value calculated at the restart among the focus evaluation values stored in the storage unit and a second lens position corresponding to a largest focus evaluation value among the focus evaluation values stored in the storage unit.

45. A camera according to claim 43, wherein:

the distance setting unit sets the distance so as to allow the photographic lens to be driven at the restart toward a close-up side of the lens position.

4. A camera comprising:

an image-capturing element that captures a subject image through a photographic lens;

an evaluation value calculation unit that calculates a focus evaluation value based upon an image-capturing signal output from the image-capturing element;

a focusing operation unit that performs a focusing operation at the photographic lens based upon the focus evaluation value;

a decision-making unit that makes a decision as to whether or not a focus evaluation value calculated by the evaluation value calculation unit after a focusing operation end manifests a change by an extent larger than a predetermined value relative to a focus evaluation value calculated at the focusing operation end over an interval matching a predetermined length of time;

a restart unit that enables the focusing operation unit in a focusing operation when the decision-making unit decides that the change by the extent larger than the predetermined value has occurred; and

a time adjustment unit that changes the predetermined length of time.

5. A camera according to claim 4, further comprising:

a determining unit that determines a time changing condition in conformance to which the predetermined length of time is changed by the time adjustment unit, wherein;

the time adjustment unit changes the predetermined length of time in conformance to the time changing condition determined by the determining unit.

16. A camera comprising:

an image-capturing element that captures a subject image through a photographic lens;

an evaluation value calculation unit that calculates a focus evaluation value based upon an image-capturing signal output from the image-capturing element;

a focusing operation unit that performs a focusing operation at the photographic lens based upon the focus evaluation value;

a restart unit that engages the focusing operation unit in a focusing operation if the focus evaluation value calculated after an end of the focusing operation manifests a change by an extent larger than a predetermined reference change quantity relative to the focus evaluation value calculated at the end of the focusing operation; and

a setting unit that sets the predetermined reference change quantity in conformance to a predetermined condition.

17. A camera according to claim 16, wherein:

the restart unit engages the focusing operation unit in the focusing operation if the focus evaluation value calculated after the end of the focusing operation manifests the change by the extent larger than the predetermined reference change quantity relative to the focus evaluation value calculated at the end of the focusing operation, in an increasing or decreasing direction.

18. A camera according to claim 16, wherein:

the restart unit engages the focusing operation unit in the focusing operation only if the focus evaluation value calculated after the end of the focusing operation manifests the change by the extent larger than a predetermined reference change quantity relative to the focus evaluation value calculated at the end of the focusing operation, in a decreasing direction.

19. A camera according to claim 16, further comprising:

a selection unit that selects either a first photographing mode suited for photographing a subject that moves slightly or almost not at all or a second photographing mode suited for photographing a subject that moves fast, wherein;

the setting unit sets a smaller value for the predetermined reference change quantity when the second photographing mode is selected by the selection unit than a value set when the first photographing mode is selected by the selection unit.

20. A camera according to claim 19, wherein:

the first photographing mode includes at least one of a normal photographing mode, a landscape photographing mode, a portrait photographing mode, a close-up photographing mode and a night photographing mode and the second photographing mode includes at least a sports photographing mode.

21. A camera according to claim 16, further comprising:

an aperture that is operated to adjust a quantity of subject light entering the image-capturing element, wherein;

the setting unit increases the predetermined reference change quantity in steps as an aperture value set at the aperture increases.

22. A camera according to claim 16, further comprising:

a photometering unit that detects a brightness of a predetermined area of the subject, wherein;

the setting unit sets a larger value for the predetermined reference change quantity as the brightness becomes lower.

23. A camera according to claim 16, wherein:

the image-capturing element includes a plurality of pixels;

a number of recording pixels to be used for recording in data of the image captured by the image-capturing element can be varied; and

the setting unit sets a larger value for the reference change quantity as the number of recording pixels becomes smaller.

24. A camera in according to claim 16, further comprising:

a detection unit that detects a full-aperture F value of the photographic lens, wherein;

the setting unit sets a larger value for the reference change quantity as the full-aperture F value increases.

25. A camera according to claim 16, further comprising:

a detection unit that detects a voltage of a camera drive battery, wherein;

the setting unit sets a larger value for the reference change quantity as the voltage of the camera drive battery becomes lower.

26. A camera according to claim 16, further comprising:

a timer that starts a time count upon completion of an initial focusing operation, wherein;

the setting unit sets a larger value for the reference change quantity as a greater length of time is counted at the timer.

27. A camera according to claim 16, wherein:

the focusing operation unit performs the focusing operation at the photographic lens at all times based upon the focus evaluation value regardless of whether or not a shutter release button has been pressed halfway down; and

the setting unit sets a smaller value for the reference change quantity while the shutter release button is held halfway down than a value set when the shutter release button is not being held halfway down.

28. A camera comprising:

an image-capturing element that captures a subject image through a photographic lens;

an evaluation value calculation unit that calculates a focus evaluation value based upon an image-capturing signal output from the image-capturing element;

a focusing operation unit that performs a focusing operation at the photographic lens based upon the focus evaluation value;

a decision-making unit that makes a decision as to whether or not the focus evaluation value calculated after an end of the focusing operation is within a shutter release enabled range over which a photographing operation is enabled;

a shutter release enabling unit that enables the photographing operation in response to a photographing command if the decision-making unit decides that the focus evaluation value is within the shutter release enabled range;

a photographing unit that executes a photographing operation if a photographing command is output while a photographing operation is enabled by the shutter release enabling unit; and

a restart unit that enables the focusing operation unit in a focusing operation based upon the focus evaluation value calculated after the end of the focusing operation, wherein;

the decision-making unit performs a decision-making operation when a preparation signal for the photographing command is output; and

the restart unit executes a restart if the focus evaluation value deviates from the shutter release enabled range based upon results of the decision made by the decision-making unit.

29. A camera according to claim 28, wherein:

when the preparation signal for the photographing command is not output, the restart unit executes a restart if the focus evaluation value deviates from a restart disabled range which is different from the shutter release enabled range.

30. A camera according to claim 29, wherein:

the restart disabled range is wider than the shutter release enabled range.

31. A camera according to claim 29, further comprising:

a setting unit that sets the shutter release enabled range in conformance to a photographing condition.

32. A camera according to claim 31, wherein:

a focal length of the photographic lens is variable and the focal length constitutes the photographing condition; and

the setting unit sets the shutter release enabled range in correspondence to the focal length.

33. A camera according to claim 31, wherein:

the photographing condition includes a first photographing mode suited for photographing a subject that moves slightly or almost not at all and a second photographing mode suited for photographing a subject that moves faster than the subject in the first photographing mode; and

the setting unit sets a narrower shutter release enabled range in the second photographing mode than in the first photographing mode.

34. A camera according to claim 33, wherein:

the first photographing mode includes at least one of a normal photographing mode, a landscape photographing mode, a portrait photographing mode, a close-up photographing mode and a night photographing mode and the second photographing mode includes at least a sports photographing mode.

35. A camera according to claim 31, further comprising:

an aperture that is operated to adjust a quantity of subject light entering the image-capturing element, wherein;

an aperture value set at the aperture constitutes the photographing condition; and

the setting unit sets a wider shutter release enabled range as the aperture value increases.

36. A camera according to claim 31, further comprising:

a photometering unit that detects a brightness of a predetermined area of the subject, wherein;

the brightness detected by the photometering unit constitutes the photographing condition; and

the setting unit sets a wider shutter release enabled range as the brightness becomes lower.

37. A camera according to claim 31, wherein:

the image-capturing element includes a plurality of pixels;

a number of recording pixels to be used for recording in data of the image captured by the image-capturing element can be varied;

the number of recording pixels constitutes the photographing condition; and

the setting unit sets a wider shutter release enabled range as the number of recording pixels becomes smaller.

38. A camera according to claim 31, further comprising:

a detection unit that detects a full-aperture F value of the photographic lens; and

a setting unit that sets the shutter release enabled range in conformance to the full-aperture F value.

39. A camera according to claim 31, further comprising:

a timer that starts a time count upon completion of a predetermined camera operation, wherein;

the setting unit sets a narrower shutter release enabled range as a greater length of time is counted at the timer.

40. A camera comprising:

an image-capturing element that captures a subject image through a photographic lens;

an evaluation value calculation unit that calculates a focus evaluation value based upon an image-capturing signal output from the image-capturing element;

a focusing operation unit that performs a focusing operation at the photographic lens based upon the focus evaluation value;

a restart unit that engages the focusing operation unit in a focusing operation when the focus evaluation value calculated after an end of the focusing operation satisfies a restart condition;

a photographing unit that performs a photographing preparation operation in response to a photographing preparation command and performs a photographing operation in response to a photographing command; and

an adjustment unit that changes the restart condition in conformance to whether or not the photographing preparation command has been issued.

41. A camera according to claim 40, wherein:

the adjustment unit changes the restart condition so as to restart the focusing operation more readily when the photographing preparation command has been issued compared to when the photographing preparation command has not been issued.

42. A camera comprising:

an image-capturing element that captures a subject image through a photographic lens;

an evaluation value calculation unit that calculates a focus evaluation value based upon an image-capturing signal output from the image-capturing element;

a focusing operation unit that performs a focusing operation at the photographic lens based upon the focus evaluation value;

a decision-making unit that makes a decision as to whether or not the focus evaluation value calculated after an end of the focusing operation is within a shutter release enabled range over which a photographing operation is enabled;

a shutter release enabling unit that enables the photographing operation in response to a photographing command if the decision-making unit decides that the focus evaluation value is within the shutter release enabled range; and

a photographing unit that executes the photographing operation if the photographing command is output while the photographing operation is enabled by the shutter release enabling unit.

46. A camera comprising:

an image-capturing element that captures a subject image through a photographic lens;

an evaluation value calculation unit that calculates a focus evaluation value based upon an image-capturing signal output from the image-capturing element;

a drive unit that moves the photographic lens along an optical axis;

a storage unit that individually stores a plurality of focus evaluation values calculated by the evaluation value calculation unit while the photographic lens is moved by the drive unit and lens positions assumed by the photographic lens when the plurality of focus evaluation values are calculated;

a focusing operation unit that performs a focusing operation by moving the photographic lens so as to achieve a maximum focus evaluation value;

a restart unit that restarts the focusing operation unit after focus is achieved by the focusing operation unit; and

a distance setting unit that sets a distance to be traveled by the photographic lens for a restart of the focusing operation unit based upon the focus evaluation values and the lens positions stored in the storage unit and the focus evaluation value calculated at the restart.