Photography – With exposure objective focusing means – focusing aid – or... – With electronic filtering
Reexamination Certificate
2002-12-17
2004-03-02
Perkey, W. B. (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
With electronic filtering
C396S103000, C396S127000
Reexamination Certificate
active
06701075
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an image sensing apparatus, focusing method, program, and storage medium, and more particularly, to an image sensing apparatus which always achieves a focused state by the hill-climbing focusing method, and before an actual image sensing operation, obtains a final focus position by re-driving (scanning) a lens in the vicinity of the focus position which has been achieved by the hill-climbing focusing method, a focusing method applied to said image sensing apparatus, a program which causes a computer to execute said focusing method, and a storage medium storing said program.
BACKGROUND OF THE INVENTION
Conventionally, as a focusing method of an electronic still camera or a video camera or the like, the lens position of a focus lens is adjusted so as to achieve a maximum level of a high-frequency-range component, consisting only of luminance signals in a high-frequency range among the luminance signals for one frame obtained from an image sensing device, e.g., a CCD.
Known methods of this focusing method are: the hill-climbing method which obtains a focus position by driving a lens in the increasing direction of a level of a high-frequency-range component (hereinafter referred to as a “focus evaluation value”) among the luminance signals for one frame obtained from an image sensing device, and obtaining as the maximum value the focus evaluation value immediately before it decreases, and acquiring a lens position corresponding to the maximum value as the focus position; or a method which obtains a focus position by storing focus evaluation values for each of the lens positions in a predetermined focusing area while driving the lens, detecting the maximum value of the stored focus evaluation values after driving the lens across the whole driving areas, and acquiring a lens position corresponding to the maximum value as the focus position.
In these methods, normally the central area of an image sensing frame is designated as the predetermined focusing area as shown in
FIG. 12
, and a focus evaluation value within this area is obtained.
FIG. 12
shows a focusing area of an image sensing frame.
FIG. 13
shows a relation between lens positions and focus evaluation values in the predetermined focusing area. As can be seen in
FIG. 13
, the focus evaluation values form a mountain shape.
Furthermore, in a case of sensing a still image by an electronic still camera or a video camera, it is a known method to always achieve a focused state of an image in the electronic view finder by the aforementioned hill-climbing focusing method, and before an actual image sensing operation, re-drive (scan) the lens in the vicinity of the focus position which has been obtained by the hill-climbing focusing method to obtain a final focus position.
However, in the above-described image sensing apparatus employing the conventional method of re-driving (scanning) a lens in the vicinity of the focus position before an actual image sensing operation, for instance, in a case where the camera performs panning and then an actual image sensing operation has started before completing the hill-climbing focusing operation, the lens may scan the area that has the center different from the intended focus position, and may go but of focus.
SUMMARY OF THE INVENTION
The present invention has been proposed in consideration of the above-described problems, and has as its object to provide an image sensing apparatus, employing a method of obtaining a final focus position before an actual image sensing operation by re-driving a lens in the vicinity of a focus position which has been obtained by the hill-climbing focusing method, which enables to achieve accurate focusing even in a case where a focus position is not yet obtained by the hill-climbing focusing method, a focusing method, a program, and a storage medium.
In order to solve the above-described problems and achieve the object, a focus adjusting apparatus according to the present invention is characterized by the following configuration according to its first aspect.
According to the present invention, the foregoing object is attained by providing a focus adjusting apparatus comprising: an extraction unit adapted to receive object light through a focus lens that performs focus adjustment, and extract a signal indicative of a focus level; a first focus operation mode adapted to perform focus operation by moving the focus lens while determining a focus level based on the signal extracted by the extraction unit, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation mode adapted to perform focus operation by storing signals extracted by the extraction unit at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control unit adapted to set a first range as the predetermined range of the second focus operation mode in a case where the second focus operation mode is executed after completing the focus operation of the first focus operation mode, or set a second range as the predetermined range of the second focus operation mode in a case where the second focus operation mode is executed before completing the focus operation of the first focus operation mode.
Furthermore, an image sensing apparatus according to the present invention is characterized by the following configuration according to its first aspect.
According to the present invention, the foregoing object is attained by providing an image sensing apparatus comprising a focus adjusting apparatus which includes: an extraction unit adapted to receive object light through a focus lens that performs focus adjustment, and extract a signal indicative of a focus level; a first focus operation mode adapted to perform focus operation by moving the focus lens while determining a focus level based on the signal extracted by the extraction unit, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation mode adapted to perform focus operation by storing signals extracted by the extraction unit at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control unit adapted to set a first range as the predetermined range of the second focus operation mode in a case where the second focus operation mode is executed after completing the focus operation of the first focus operation mode, or set a second range as the predetermined range of the second focus operation mode in a case where the second focus operation mode is executed before completing the focus operation of the first focus operation mode.
Furthermore, a focus adjusting apparatus according to the present invention is characterized by the following configuration according to its second aspect.
According to the present invention, the foregoing object is attained by providing a focus adjusting apparatus comprising: an extraction unit adapted to receive object light through a focus lens that performs focus adjustment, and extract a signal indicative of a focus level; a first focus operation mode adapted to perform focus operation by moving the focus lens while determining a focus level based on the signal extracted by the extraction unit, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a sec
Morgan & Finnegan , LLP
Perkey W. B.
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