Photography – With exposure objective focusing means – focusing aid – or... – Processing circuit
Reexamination Certificate
2003-03-21
2004-04-13
Perkey, W. B. (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
Processing circuit
C348S356000
Reexamination Certificate
active
06721499
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a camera capable of a focusing adjustment by a contrast method using an imaging signal output by an imaging element.
2. Description of Related Art
In this field of the art, as one of ways of automatic focus (AF) adjustments for use in a camera, there is a so-called contrast method. According to this method, an object is picked up by an imaging element such as CCD or so and an in-focus position is determined by using an imaging signal in a focus area. More specifically, a component of a given spatial frequency band of an imaging signal in a focus area is extracted through a band pass filter (BPF). By integration of these absolute values in an area, a focus evaluation value in causing a focusing operation is calculated. This focus evaluation value represents a contrast size, high or low and a peak of focus evaluation value shows a highest contrast. Namely, a peak value position turns out to be an in-focus position.
As a way of detecting a peak value position, what is called a mountain climb control method and a full scan control method are known. A single AF mode in which an automatic focusing is performed only when a halfway-depress switch is halfway depressed and a focus point is held unless a halfway-depressed switch is released and a continuous AF mode in which an automatic focusing operation is always being performed continuously regardless of an operation of a halfway-depress switch are known.
SUMMARY OF THE INVENTION
In a continuous AF mode, it is pointed out that when a halfway-depress switch is turned on, a suitable focusing control method is not always selected. It is an object of this invention to provide a camera enabling to select a suitable focusing control method when a halfway-depress switch is turned on.
In order to achieve the object, according to one aspect of this invention, there is provided a camera which includes an imaging element that picks up an image of an object through a taking-lens, an evaluation value calculator that calculates focus evaluation value based upon an imaging signal output by the imaging element, a selector that selects one focusing mode from a plurality of focusing modes, a focusing device that performs a focusing operation of the taking-lens based upon the focus evaluation value and the selected focusing mode and a rebooting device that reboots the focusing operation after the focusing operation performed by the focusing device finishes, an evaluation value memory device that obtains and stores a plurality of focus evaluation values calculated in time sequence by the evaluation value calculator after the focusing operation performed by the focusing device finishes and a fluctuation evaluator that evaluates fluctuation in focus evaluation value based upon a plurality of focus evaluation values stored into the evaluation value memory device, wherein, when the rebooting device reboots the focusing operation, the selector selects one focusing mode from a plurality of focusing modes based upon an evaluation result of fluctuation in focus evaluation value by the fluctuation evaluator.
According to claim
2
set forth in this invention, there is provided the camera disclosed in claim
1
, wherein a plurality of focusing modes have a mountain climb focus mode using a so-called mountain climb control method that seeks a peak value of the focus evaluation value while moving the taking-lens in a direction with the focus evaluation value getting larger every a single cycle of calculating the focus evaluation value and a full range scan focus mode using a so-called full range scanning control method that seeks a peak value of the focus evaluation value by scanning across an overall movement range for use in focusing the taking-lens.
According to claim
3
set forth in this invention, there is provided the camera disclosed in claim
2
, wherein the selector selects the mountain climb focus mode when the fluctuation evaluator judges that fluctuation in focus evaluation value is monotonous.
According to claim
4
set forth in this invention, there is provided the camera disclosed in claim
3
, wherein a monotonous fluctuation in focus evaluation value means a monotonous increase or decrease in focus evaluation value within a given period of time.
According to claim
5
set forth in this invention, there is provided the camera disclosed in claim
2
, wherein the selector selects the full range scan control mode when the fluctuation evaluator judges that fluctuation in focus evaluation value is not monotonous.
According to claim
6
set forth in this invention, there is provided the camera disclosed in claim
2
, wherein the selector moves the taking-lens to an end of the movement range and selects the mountain climb focus mode when the fluctuation evaluator judges that fluctuation in focus evaluation value is not monotonous.
According to claim
7
set forth in this invention, there is provided the camera disclosed in claim
6
, wherein the end of the movement range is an end at a closest distance away.
According to claim
8
set forth in this invention, there is provided a camera which includes an imaging element that picks up an image of an object through a taking-lens, an evaluation value calculator that calculates focus evaluation value based upon an imaging signal output by the imaging element, a selector that selects one focusing mode from a plurality of focusing modes, a focusing device that performs a focusing operation of the taking-lens based upon the focus evaluation value and the selected focusing mode and a rebooting device that reboots the focusing operation after the focusing operation performed by the focusing device finishes, wherein further comprising a plurality of focusing modes that have a mountain climb focus mode using a so-called mountain climb control method that seeks a peak value of the focus evaluation value while moving the taking-lens in a direction with the focus evaluation value getting larger every a single cycle of calculating the focus evaluation value and a full range scan focus mode using a so-called a full range scanning focus control method that seeks a peak value of focus evaluation value by scanning across an overall movement range for use in focusing the taking-lens, wherein, when the rebooting device reboots the focusing operation, the selector selects the full range scan focus mode when the selector judges that focus evaluation value at rebooting is smaller than a given value.
According to claim
9
set forth in this invention, there is provided the camera disclosed in claim
8
, wherein the given value is a value calculated based upon focus evaluation value at a conclusion of the focusing operation.
According to claim
10
set forth in this invention, there is provided a camera which includes an imaging element that picks up an image of an object through a taking-lens, an evaluation value calculator that calculates focus evaluation value based upon an imaging signal output by the imaging element, a selector that selects one focusing mode from a plurality of focusing modes, a focusing device that performs a focusing operation of the taking-lens based upon the focus evaluation value and the selected focusing mode and a rebooting device that reboots the focusing operation after the focusing performed by the focusing device finishes, wherein, when the rebooting device reboots the focusing operation, the selector selects one focusing mode based upon a shooting condition.
According to claim
11
set forth in this invention, there is provided the camera disclosed in claim
10
, wherein the shooting condition is a condition based upon a focal length of the taking-lens.
According to claim
12
set forth in this invention, there is provided the camera disclosed in claim
11
, wherein a plurality of focusing modes have a mountain climb focus mode using a so-called mountain climb control method that seeks a peak value of the focus evaluation value while moving the taking-lens in a direction with the focus evaluation value getting la
Hibino Hideo
Maeda Toshiaki
Ohta Tadashi
Watanabe Toshimi
Nikon Corporation
Oliff & Berridg,e PLC
Perkey W. B.
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