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Digital Camera Patent Abstract
There is disclosed a digital camera which detects a focus of a lens
unit by a method selected from a plurality of focus detection methods
based on information on the lens unit taken from the lens unit attached
to the digital camera. As an example of a focus detection method,
there is a method by a phase difference system or a contrast system,
but the method is not limited to this example.
Digital Camera Patent Claims
1. A digital camera to which a lens unit having a focus lens is
detachably attached, comprising:an imaging section having an image
pickup device to convert an optical image of a subject irradiated
via the lens unit into an electrical signal;a first focus detecting
section which detects focal information of the focus lens by a first
focus detection method;a second focus detecting section which detects
focal information of the focus lens by a second focus detection
method;a control section which selects the focal information detected
by at least one of the first focus detecting section and the second
focus detecting section and which generates a focusing control signal
to control a focal position of the focus lens based on the selected
focal information; anda transmitting and receiving section which
transmits the focusing control signal to the lens unit and which
receives information on the lens unit transmitted from the lens
unit,wherein the control section selects the focal information based
on the information on the lens unit acquired via the transmitting
and receiving section.
2. The digital camera according to claim 1, wherein the control
section generates a signal to control a lens position of the focus
lens so that the optical image of the subject is formed on the image
pickup device.
3. The digital camera according to claim 2, wherein the first focus
detection method is a focus detection method performed by a phase
difference system, andthe second focus detection method is a focus
detection method performed by a contrast system.
4. The digital camera according to claim 3, wherein the lens unit
includes a focus driving section which moves the focus lens, andthe
information on the lens unit includes information for use in moving
the focus lens by the focus driving section.
5. The digital camera according to claim 4, wherein the information
on the lens unit includes information indicating a system of focusing
control related to the lens unit or information indicating a type
of a member which moves the focus lens.
6. The digital camera according to claim 4, wherein the information
on the lens unit includes information indicating a focal length
or a shootable distance of the lens unit.
7. The digital camera according to claim 4, wherein the information
on the lens unit includes information indicating a movable range
of the focus lens of the lens unit.
8. The digital camera according to claim 4, wherein the information
on the lens unit includes information indicating a movement speed
of the focus lens.
9. The digital camera according to claim 1, wherein the control
section further has a judgment section which judges whether or not
a conversion lens or a extension tube is attached to the lens unit,
andthe control section performs the selection based on a judgment
result obtained by the judgment section.
10. A camera system comprising: a camera main body; and a lens
unit detachably attached to the camera main body,the lens unit including:a
focus lens;a focus driving section which moves the focus lens; anda
storage section in which information on the lens unit is stored;
anda communication section which communicates with the camera main
body,the camera main body including:an imaging section having an
image pickup device to convert an optical image of a subject irradiated
via the lens unit into an electrical signal;a first focus detecting
section which detects focal information of the focus lens by a first
focus detection method;a second focus detecting section which detects
focal information of the focus lens by a second focus detection
method;a control section which selects the focal information detected
by at least one of the first focus detecting section and the second
focus detecting section and which generates a focusing control signal
to control a focal position of the focus lens based on the selected
focal information; anda transmitting and receiving section which
receives information on the lens unit transmitted from the lens
unit via the communication section and which transmits the focusing
control signal to the lens unit,the control section being configured
to select the focal information based on the information on the
lens unit acquired via the transmitting and receiving section.
11. The camera system according to claim 10, wherein the information
on the lens unit stored in the storage section is information for
use in moving the focus lens by the focus driving section, and includes
at least one of information indicating a system of focusing control
related to the lens unit, information indicating a type of a member
which moves the focus lens, information indicating a focal length
of the focus lens, information indicating a shootable distance of
the lens unit, information indicating a movable range of the focus
lens of the lens unit and information indicating a movement speed
of the focus lens.
12. A focusing control method in which a lens unit attached to
a digital camera is focused, comprising:performing communication
between a main body of the digital camera and the lens unit to take
information on the lens unit into the main body of the digital camera
from the lens unit;selecting a focusing control method suitable
for the lens unit from imager AF and TTL phase-difference AF based
on the information on the lens unit in the digital camera; andas
a result of the selection, (1) controlling a focus of the lens unit
by the only imager AF in a case where the only imager AF is selected,(2)
controlling the focus of the lens unit by the only TTL phase-difference
AF in a case where the only TTL phase-difference AF is selected,
or(3) coarsely controlling the focus of the lens unit by the TTL
phase-difference AF and then adjusting the focus of the lens unit
by the imager AF in a case where both of the TTL phase-difference
AF and the imager AF are selected.
13. The focusing control method according to claim 12, wherein
a scan region during the imager AF in a case where both of the TTL
phase-difference AF and the imager AF are selected is smaller than
that during the imager AF in a case where the only imager AF is
selected.
Digital Camera Patent Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001]This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2006-136668,
filed on May 16, 2006, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002]1. Field of the Invention
[0003]The present invention relates to a digital camera and a camera
system having an automatic focusing (AF) control function.
[0004]2. Description of the Related Art
[0005]Heretofore, as an AF mechanism disposed in a single-lens
reflex camera using a film and a single-lens reflex digital camera,
a through-the-lens (TTL) phase-difference AF mechanism has been
frequently used. In this case, a defocus detection mechanism which
performs the TTL phase-difference AF is disposed in a main body
of the single-lens reflex camera. Moreover, a focusing lens disposed
in a lens barrel of an interchangeable lens which is detachably
attached to the single-lens reflex cameras is driven by a motor
disposed in the lens barrel of the interchangeable lens or the main
body of the single-lens reflex camera to perform a focusing control
operation. It is to be noted that the TTL phase-difference AF is
sometimes referred to simply as the phase-difference AF.
[0006]On the other hand, in a compact digital camera, a camcorder
or the like, so-called imager AF is frequently performed which is
AF of such a system that contrast is detected with a high frequency
component of a signal of an image pickup device. Here, the imager
AF is an auto focusing method where an evaluated focal value of
a focus lens at each focus lens position is calculated while moving
the focus lens at a predetermined driving amount interval, and the
focus lens position where the evaluated focal value reaches a peak
value is obtained.
[0007]It is to be noted that the TTL phase-difference AF and the
imager AF have the following characteristics, respectively.
[0008]The TTL phase-difference AF is the AF at a speed higher than
that of the imager AF.
[0009]The imager AF is the AF having a precision higher than that
of the TTL phase-difference AF.
[0010]Based on such characteristics, the TTL phase-difference AF
and the imager AF are selectively used in accordance with an application.
Here, as a technology in selectively using the TTL phase-difference
AF and the imager AF, for example, the following technology is known.
[0011]In Japanese Patent Application Laid-Open No. 7-43605, an
automatic focusing device is disclosed in which the TTL phase-difference
AF is combined with the imager AF to perform focusing control. Specifically,
in this automatic focusing device, after coarse control is performed
by the TTL phase-difference AF, fine control is performed by the
imager AF.
[0012]Moreover, in Japanese Patent Application Laid-Open No. 2003-302571,
an automatic focusing control device is also disclosed in which
after the coarse control is performed by the TTL phase-difference
AF, the fine control is performed by the imager AF in the same manner
as in the automatic focusing device disclosed in Japanese Patent
Application Laid-Open No. 7-43605. However, in this automatic focusing
control device disclosed in Japanese Patent Application Laid-Open
No. 2003-302571, to speed us the focusing, the TTL phase-difference
AF is selected in preference to the imager AF, when it is decided
that the focusing is possible with the TTL phase-difference AF alone.
[0013]In addition, for a lens-interchangeable single-lens reflex
camera using a film, many interchangeable lenses are on sale and
already spread widely. Here, many of the interchangeable lenses
which have already spread are designed to perform the TTL phase-difference
AF. That is, focusing control mechanisms and the like of the focus
lenses disposed in the lens barrels of many interchangeable lenses
are designed as a system which drives the lens by a driving amount
corresponding to a detected defocus amount. Specifically, as a driving
source for the focusing control in the interchangeable lens barrel,
a direct-current motor (a DC motor) is employed in many cases. On
the other hand, as the driving source of the focus lens in the imager
AF, a stepping motor is optimum. In actual, stepping motors are
employed in many cases of the imager AF.
BRIEF SUMMARY OF THE INVENTION
[0014]The present invention relates to detecting a focus of a lens
unit by a method selected from a plurality of focus detection methods
based on information on the lens unit taken into a digital camera
from the lens unit, which is attached to the digital camera.
[0015]Next, one example of a structure of the present invention
will be described. A digital camera to which a lens unit having
a focus lens as a shooting optical system is detachably attached,
comprising: an imaging section having an image pickup device to
convert an optical image of a subject which has struck via the lens
unit into an electrical signal; a first focus detecting section
which detects focal information of the focus lens by a first focus
detection method; a second focus detecting section which detects
focal information of the focus lens by a second focus detection
method; a control section which selects the focal information detected
by at least one of the first focus detecting section and the second
focus detecting section and which generates a focusing control signal
to control a focal position of the focus lens based on the selected
focal information; and a transmitting and receiving section which
transmits the focusing control signal to the lens unit and which
receives information on the lens unit transmitted from the lens
unit, wherein the control section selects the focal information
based on the information on the lens unit acquired via the transmitting
and receiving section.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0016]These and other features, aspects, and advantages of the
apparatus and methods of the present invention will become better
understood with regard to the following description, appended claims,
and accompanying drawings where:
[0017]FIG. 1 is a diagram showing a system structure of a digital
camera according to a first embodiment of the present invention;
[0018]FIG. 2 is a diagram showing an internal structure of a second
focus detecting section;
[0019]FIG. 3 is a graph of an evaluated AF value to a focus lens
position;
[0020]FIG. 4 is a diagram showing a structure of a phase-difference
AF sensor unit;
[0021]FIG. 5 is a diagram showing a concept to calculate a phase
difference which is a relative positional relation between two subject
images;
[0022]FIG. 6 is a diagram mainly showing a component concerning
TTL phase-difference AF in the digital camera according to a first
embodiment of the present invention;
[0023]FIG. 7 is a graph showing one example of a relation between
i and F(i);
[0024]FIG. 8 is a flow chart showing operation control performed
by a control section of the digital camera according to the first
embodiment of the present invention;
[0025]FIG. 9 is a diagram showing a lens type correspondence table;
[0026]FIG. 10 is a flow chart showing operation control of imager
AF performed by the control section of the digital camera according
to the first embodiment of the present invention;
[0027]FIG. 11 is a flow chart showing operation control performed
by a lens control section of the digital camera according to the
first embodiment of the present invention;
[0028]FIG. 12 is a timing chart showing a timing of the operation
control performed by the imager AF;
[0029]FIG. 13 is a flow chart showing the operation control performed
by the control section of the digital camera according to a second
embodiment of the present invention;
[0030]FIG. 14 is a flow chart showing the operation control performed
by the control section of the digital camera according to a third
embodiment of the present invention;
[0031]FIG. 15 is a diagram showing driving source data for judgment
of a driving source; and
[0032]FIG. 16 is a flow chart showing the operation control performed
by the control section of the digital camera according to a fourth
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0033]Preferred embodiments of the invention are described below
with reference to the accompanying drawings.
First Embodiment
[0034]A digital camera and a camera system according to a first
embodiment of the present invention will hereinafter be described
with reference to the drawings. FIG. 1 is a diagram showing a system
structure of the digital camera according to the first embodiment
of the present invention. It is to be noted that in the first embodiment,
a single-lens reflex digital camera is assumed as the digital camera
and described.
[0035]First, in FIG. 1, reference numeral 1 is a camera body. Reference
numeral 2 is an interchangeable lens as a lens unit.
[0036]Here, the interchangeable lens 2 has a photographing lens
system 3, a lens driving section 4, a lens control section 5, an
encoder 15 and a storage section 5A.
[0037]The photographing lens system 3 includes a focus lens 3A.
Moreover, during focusing control, the focus lens 3A is moved to
control a focus. The lens driving section 4 is a section which moves
the focus lens 3A in an optical axis direction. The lens control
section 5 is a communicating section which communicates with the
camera body 1 as well as a control section which controls the lens
driving section 4. The encoder 15 is an encoder which generates
a pulse signal in response to movement of the focus lens 3A and
which outputs the pulse signal to the lens control section 5. Information
including a lens type and a characteristic of the lens.
[0038]It is to be noted that the lens control section 5 counts
output pulses of the encoder 15 to recognize a position of the focus
lens 3A.
[0039]On the other hand, the camera body 1 has a half mirror 6,
an image pickup device (imaging section) 7, a phase-difference AF
sensor unit 9, an LCD panel 10, a finder optical system 11, a first
focus detecting section 12, an image processing section 13, a second
focus detecting section 14, a control section 16 and a release switch
18.
[0040]The half mirror 6 is a member which divides a shot luminous
flux into a luminous flux to the image pickup device 7 and a luminous
flux to the phase-difference AF sensor unit 9. According to such
a structure, an image pickup operation and an operation for phase-difference
AF can simultaneously be performed. The LCD panel 10 is an LCD panel
for an electronic view finder in which a backlight is incorporated.
The finder optical system 11 is a member for a user to observe the
LCD panel 10. The first focus detecting section 12 is a member which
calculates a defocus amount or the like from an output of the phase-difference
AF sensor unit 9.
[0041]The image processing section 13 subjects a picture signal
output from the image pickup device 7 to white balance adjustment,
luminance processing, color matrix processing and the like, and
forms image data as a shot image and image data for a finder. in
addition to the formation of the image data, the image processing
section 13 acquires processes a signal output from the image pickup
device 7 to acquire image information.
[0042]The image data for the finder formed by the image processing
section 13 is sent to the LCD panel 10, and displayed in the LCD
panel 10. Moreover, the image data for the finder is observed by
the user via the finder optical system 11. The image data as the
shot image is stored in a nonvolatile memory (not shown) or the
like.
[0043]Furthermore, the image processing section 13 generates a
driving control signal of the image pickup device 7 based on a reference
clock (not shown) sent from the control section 16 described later.
Specifically, the image processing section 13 generates a timing
signal of start/end (start/end of exposure) of integration of the
image pickup device 7 and a clock signal such as a readout control
signal (a horizontal sync signal, a vertical sync signal VD, a transfer
signal or the like) of a light receiving signal of each pixel and
the like, and outputs the signals to the image pickup device 7.
[0044]Here, the image processing section 13 outputs the vertical
sync signal VD to the second focus detecting section 14, the control
section 16 and the lens control section 5. It is to be noted that
a signal VDP which agrees with the vertical sync signal VD is output
to the lens control section 5 via a lens contact section (a transmitting
and receiving section) 8. The lens contact section 8 is a lens contact
to which the control section 16 disposed in the camera body 1, a
communication line with the lens control section 5 disposed in the
interchangeable lens 2 and the like are connected. It is to be noted
that the lens contact section 8 has a plurality of contacts required
for connection of a plurality of power sources including a lens
power source to be supplied from the camera body 1 to the interchangeable
lens 2 and transmission of a plurality of signals including the
vertical sync signal.
[0045]The second focus detecting section 14 is a member which judges
a magnitude of change of a luminance signal obtained from the image
processing section 13 to calculate an evaluated AF value indicating
a degree of focusing. It is to be noted that a focus detection area
which is an area to calculate the evaluated AF value is predetermined
as a region which agrees with the focus detection area during the
phase difference detection. The control section 16 is a member which
controls the whole camera body 1 and interchangeable lens 2.
[0046]It is to be noted that in the camera according to the first
embodiment, a release button (not shown) is a two-stage type button
to be pressed. When the button is pressed halfway, a first release
switch (hereinafter referred to as 1RSW) is turned on, and a focus
detecting operation is performed described later. When the release
button (not shown) is fully pressed, a second release switch (hereinafter
referred to as 2RSW) is turned on, and a shooting operation is performed
as described later. Here, the 1RSW corresponds to the release switch
18.
[0047]First, imager AF (AF using a focus detection method performed
by a contrast system) will be described with reference to FIGS.
2 and 3.
[0048]First, as shown in FIG. 2, in the second focus detecting
section 14, a high pass filter (HPF) 131, an A/D converter 132,
a focus detection area selection gate 133 and an adder 134 are connected
in this order. Here, each section component member disposed in the
second focus detecting section 14 is a circuit block to obtain the
evaluated AF value.
[0049]The image processing section 13 inputs the luminance signal
generated from an output signal of the image pickup device 7 into
the HPF 131 of the second focus detecting section 14. Moreover,
this luminance signal is processed as follows in the image processing
section 13.
[0050]First, high frequency components included in the luminance
signal are extracted from the luminance signal by the HPF 131. When
sharpness of an image is high, a larger amount of the extracted
high frequency components are extracted. Therefore, the high frequency
components of a predetermined image range can be integrated to obtain
a numeric value of an average degree of the image sharpness in the
image range.
[0051]Next, the high frequency component passed through the HPF
131 is converted into a digital signal by the A/D converter 132,
and input into the focus detection area selection gate 133. This
focus detection area selection gate 133 is a circuit which extracts
only signals corresponding to a plurality of focus detection areas
of an imaging screen. Therefore, the focus detection area selection
gate 133 extracts only information on a subject, reflected in the
focus detection area corresponds to the predetermined image range
for the integration.
[0052]Here, as the focus detection area, a focus detection area
selected based on a predetermined selection algorithm (e.g., a closest
selection algorithm) may be employed. Needless to say, a focus detection
area selected from the plurality of focus detection areas by the
user may be employed.
[0053]Moreover, the digital signal extracted by the focus detection
area selection gate 133 is input into the adder 134. Furthermore,
the digital signals of a portion of the focus detection area of
one frame are integrated. It is to be noted that a value integrated
by this adder 134 is input as the evaluated AF value indicating
the sharpness of the image into the control section 16. The control
section 16 can perform the imager AF which is auto focusing of a
known mountain climbing system by use of the evaluated AF value
calculated as described above.
[0054]It is to be noted that the image processing section 13 outputs
the luminance signal to the second focus detecting section 14, and
outputs the sync signal to the focus detection area selection gate
133, the adder 134 and the control section 16 in response to the
picture signal.
[0055]Here, to perform the imager AF, the control section 16 moves
the focus lens 3A by the lens driving section 4 via the lens control
section 5. Moreover, position information of the focus lens 3A from
an output of the encoder 15. Furthermore, the evaluated AF value
is input from the adder 134. As shown in FIG. 3, the evaluated AF
value of the position of the focus lens 3A is obtained as evaluated
AF coordinate values ((P1, H1), (P2, H2) and (P3, H3).
[0056]Moreover, the control section 16 calculates a lens position
of the focus lens 3A at a time when the evaluated AF value reaches
a maximum value, that is, a peak value by interpolation using the
above evaluated AF coordinate value. Subsequently, the focus lens
3A is moved to a focus target position PM which is the lens position
at the time when the evaluated AF value reaches the peak value.
[0057]Next, TTL phase-difference AF will be described.
[0058]First, as shown by a broken line of FIG. 4, the phase-difference
AF sensor unit 9 has a view field mask 101, a condenser lens 102,
aperture masks 103A and 103B, secondary optical systems 104A and
104B and photoelectric conversion element rows 105A and 105B.
[0059]As shown in FIG. 4, the view field mask 101 is disposed in
the vicinity of a scheduled imaging surface on which a subject image
is formed by the photographing lens system 3. Furthermore, the condenser
lens 102 is disposed in the vicinity of the view field mask 101.
In addition, the aperture masks 103A and 103B are aperture masks
with openings, and arranged behind the condenser lens 102 along
an optical path of the condenser lens. Moreover, the secondary optical
systems 104A and 104B include secondary imaging lenses, and arranged
behind the aperture masks 103A and 103B along the optical path.
The photoelectric conversion element rows 105A and 105B are arranged
behind the secondary imaging lenses along the optical path. It is
to be noted that, as shown in FIG. 4, the photographing lens system
3 can define two different pupil areas 106A and 106B.
[0060]According to such a structure, two subject images formed
by the luminous fluxes passed through the pupil areas 106A and 106B
of the photographing lens system 3 are formed on the photoelectric
conversion element rows 105A and 105B, respectively. The focus is
detected using a fact that a relative positional relation between
two subject images formed again in this manner changes with a focused
state of the photographing lens system 3. It is to be noted that
a phase difference which is this relative positional relation between
the two subject images can be calculated by obtaining correlation
between the positions. A concept of this calculation will hereinafter
be described with reference to FIG. 5.
[0061]That is, an area S (a sum of absolute values of differences
of outputs between the corresponding pixels of images A and B) of
a region where two subject images (the images A and B) are not superimposed
on each other is assumed as hatched in FIG. 5. Moreover, one image
(the image A of the present example) is shifted every pixel (one
bit) of the photoelectric conversion element to obtain a minimum
value of the area S.
[0062]Here, when the image A agrees with the image B, the area
S naturally has the minimum value. Moreover, a defocus amount of
one image (the image A of the present example) required for bringing
about this minimum value is the phase difference which is a relative
defocus amount. As described above, assuming that an interval between
gravity centers of the two pupil areas 106A and 106B is a base line
length during triangle measurement, a defocus amount of the photographing
lens system 3 can be obtained based on the phase difference which
is the relative defocus amount along the photoelectric conversion
element rows 105A and 105B.
[0063]FIG. 6 is a drawing mainly showing an extracted component
concerning the TTL phase-difference AF in the digital camera according
to the first embodiment. Here, the photoelectric conversion element
rows 105A and 105B are included in the phase-difference AF sensor
unit 9. An A/D converter 111 is included in the first focus detecting
section 12. Analog outputs from the pixels of the photoelectric
conversion element rows 105A and 105B are converted into digital
signals by the A/D converter 111. Furthermore, a calculation processing
section 112 such as a microcomputer is incorporated in the first
focus detecting section 12. According to the above structure, the
phase difference between the two images (the images A and B) is
obtained, and the focus lens 3A is controlled based on this phase
difference. This will hereinafter be described specifically.
[0064]First, it is assumed that output values of the photoelectric
conversion element row 105A which have been A/D converted by the
A/D converter 111 are L(1), L(2), L(n) and that output values of
the photoelectric conversion element row 105B which have been A/D
converted by the A/D converter 111 are R(1), R(2), . . . , R(n).
Here, 1 to n correspond to the photoelectric conversion elements,
and are represented by variables i.
[0065]Here, a correlation function F(i) indicating an agreement
degree of the image with respect to the relative defocus amount
(the phase difference) of two images represented by the phase difference=ip
(p is a pixel pitch) is given by, for example, Equation (1).
F ( i ) = j L ( j ) - R ( j + 1 ) ( 1 )
[0066]If two images of the photoelectric conversion element rows
105A and 105B relatively defocus at a pitch of k pixels, F(k)=0
results from Equation (1). However, owing to an influence of a pixel
noise or the like, a form of an image signal of the photoelectric
conversion element row 105A is not completely the same as that of
an image signal of the photoelectric conversion element row 105B.
Therefore, F(k)>0 usually results.
[0067]FIG. 7 shows one example of the above relation between i
and F(i). As described above, (i, F(i)) is actually discrete data,
but FIG. 7 shows a continuous graph for the sake of convenience.
It is to be noted that after obtaining the minimum value of F(i)
in a predetermined range of i, the interpolation is performed using
correlation function values before and after the minimum value in
order to perform highly precise detection.
[0068]The operation control performed by the control section 16
of the digital camera according to the first embodiment will hereinafter
be described with reference to a flow chart of FIG. 8.
[0069]First, when the user turns on the power source (not shown)
disposed in the camera body 1, the control section 16 of the camera
body 1 communicates with the lens control section 5 of the interchangeable
lens 2 (step S100). Specifically, in this step S100, the control
section 16 reads out various data concerning this lens stored in
the storage section 5A of the interchangeable lens 2, and stores
the data in a storage section (not shown) of the control section
16.
[0070]It is to be noted that communication between the control
section 16 of the camera body 1 and the lens control section 5 of
the interchangeable lens 2 will hereinafter be referred to as body
and lens communication. Examples of the data concerning the interchangeable
lens 2 to be communicated during this body and lens communication
include information such as the lens type of the interchangeable
lens 2, a focal length, a shootable distance, a movable range of
the focus lens, the total number of focus pulses corresponding to
the whole region of a shooting distance, a motor type and various
corrected values concerning the AF.
[0071]Subsequently, the user half presses the release button to
wait until the release switch 18 (the 1RSW) is turned on (step S101).
Moreover, when the 1RSW is turned on, the step S101 is branched
to YES to start a focusing operation by the auto focusing.
[0072]First, the lens type of the interchangeable lens 2 is judged
(step S102). Specifically, during the judgment of the lens type
in this step S102, with reference to the lens type data acquired
by the body and lens communication in the step S100, the lens type
of the interchangeable lens 2 is judged based on a lens type correspondence
table shown in FIG. 9. Here, the lens type correspondence table
is a table in which three lens type data (0, 1 and 2) are associated
with AF aptitudes of the lens type data.
[0073]It is to be noted that the lens type 0 indicates that the
interchangeable lens deals with the only phase-difference AF. The
lens type 1 indicates that the interchangeable lens deals with the
only imager AF. Furthermore, the lens type 2 indicates that the
interchangeable lens deals with both of the phase-difference AF
and the imager AF.
[0074]After ending the processing of the step S102, it is judged
whether or not the lens type of the interchangeable lens 2 is the
lens type 1 (step S103). In a case where it is judged in the step
S103 that the interchangeable lens 2 is the lens type 1, the processing
shifts to the step S110 described later. On the other hand, in a
case where it is judged in the step S103 that the interchangeable
lens 2 is not the lens type 1, it is judged whether or not the interchangeable
lens 2 is the lens type 0 (step S104). In a case where it is judged
in this step S104 that the interchangeable lens 2 is the lens type
0, the processing shifts to step S115 described later.
[0075]In a case where it is judged in the step S104 that the interchangeable
lens 2 is not the lens type 0 (in a case where the interchangeable
lens 2 is the lens type 2), the phase difference is detected (step
S105). During the detection of the phase difference in this step
S105, the first focus detecting section 12 acquires a signal from
the phase-difference AF sensor unit 9, and calculates the defocus
amount. In the step S105, it is evaluated whether or not the phase
difference can be detected, and reliability of the phase difference
detection is also calculated.
[0076]Subsequently, it is judged whether or not a highly reliable
defocus amount has been obtained during the phase difference detection
in the step S105. In other words, it is judged whether or not the
phase difference can be detected (step S106). In a case where it
is judged in this step S106 that the phase difference can be detected,
it is judged whether or not the defocus amount detected in the step
S105 is in a predetermined range described later (step S107). It
is to be noted that this predetermined range is a range predetermined
by assuming that the focusing operation can be performed sufficiently
highly precisely at a high speed by the imager AF in a case where
the defocus amount is in the above range.
[0077]In a case where it is judged in the step S107 that the defocus
amount is in the predetermined range, an in-range flag indicating
this effect is set (step S130). Furthermore, the processing shifts
to step S110 described later.
[0078]In addition, in a case where it is judged in the step S107
that the defocus amount is not in the above predetermined range,
a lens driving amount and a driving direction of the focus lens
3A required for obtaining the focused state are calculated from
the obtained defocus amount (step S108). Moreover, the focus lens
3A is driven based on the lens driving amount and the driving direction
calculated in the step S108 (step S109).
[0079]Specifically, in the step S109, the lens driving amount and
the driving direction calculated in the step S108 are transmitted
as a phase-difference AF lens driving command to the lens control
section 5 of the interchangeable lens 2 via the lens contact section
8. Moreover, the lens control section 5 controls the lens driving
section 4 to drive the focus lens 3A. After ending the processing
of the step S109, the processing returns to the step S105. In a
case where conditions of the steps S106 and S107 are not satisfied
in this manner, the focus of the focus lens 3A is firstly coarsely
adjusted by the phase-difference AF. Subsequently, the above conditions
are checked again.
[0080]In addition, in a case where it is judged in the step S106
that the phase difference cannot be detected, and after it is judged
in the step S107 that the defocus amount is in the predetermined
range to end the processing of the step S130, the imager AF is executed
(step S110). Specific processing contents of this imager AF will
be described later in detail with reference to a flow chart of FIG.
10. After ending the processing of the imager AF in the step S119,
it is judged from the result of the imager AF whether or not the
focused state has been obtained (step S111).
[0081]In a case where it is judged in the step S111 that the focused
state can be obtained, focusing display indicating that the focused
state has been obtained is displayed in the LCD panel 10 by the
image processing section 13 (step S112). On the other hand, in a
case where it is judged in the step S111 that the focused state
is not obtained, the image processing section 13 displays, in the
LCD panel 10, that the focused state is not obtained (step S113).
[0082]Moreover, after ending the processing of the step S112 or
the S113, the user fully presses the release button to instruct
the shooting, and the shooting is performed based on a usual shooting
sequence (step S114).
[0083]After ending the processing of the step S114, the in-range
flag is reset in a case where the in-range flag is set in the step
S139 (step S131). Moreover, the step waits until the release switch
18, that is, the 1RSW turns off (step S132). In a case where it
is judged in this step S132 that the 1RSW turns off, the processing
returns to the step S101.
[0084]In addition, in a case where it is judged in the step S104
that the interchangeable lens 2 is the lens type 0, the phase difference
is detected (step S115). Specifically, in this step S115, the defocus
amount is calculated by the first focus detecting section 12 based
on the signal output from the phase-difference AF sensor unit 9.
It is evaluated whether or not the phase difference can be detected,
and the reliability of the detection is calculated.
[0085]Subsequently, it is judged whether or not the highly reliable
defocus amount has been obtained during the phase difference detection
of the step S115 (step S116). In a case where it is judged in this
step S116 that the phase difference can be detected, it is judged
whether or not the detected current defocus amount is in a focused
range (step S117). Here, the focused range indicates a numeric value
predetermined by assuming that the focused state is obtained in
a case where the defocus amount is in this range. In a case where
it is judged in this step S117 that the current defocus amount is
not in the focused range, the driving amount and the driving direction
of the focus lens 3A required for obtaining the focused state are
calculated based on the defocus amount (step S118).
[0086]Moreover, the focus lens 3A is driven based on the driving
amount and the driving direction of the focus lens 3A calculated
in the step S118 (step S119). Specifically, the lens driving amount
and the driving direction calculated in the step S118 are transmitted
as the phase-difference AF lens driving command to the lens control
section 5 of the interchangeable lens 2. Moreover, the lens control
section 5 controls the lens driving section 4 to drive the focus
lens 3A. Subsequently, the processing returns to the step S115.
[0087]In addition, in a case where it is judged in the step S116
that the phase difference cannot be detected, the image processing
section 13 displays, in the LCD panel 10, that the focused state
is not obtained (step S121). In a case where it is judged in the
step S117 that the current defocus amount is in the focused range,
the focused display indicating that the focused state is obtained
is displayed in the LCD panel 10 by the image processing section
13 (step S120). Moreover, after ending the processing of this step
S120 or S121, the processing shifts to the shooting sequence of
the step S114.
[0088]As described above, in the digital camera according to the
first embodiment, when the interchangeable lens 2 is the lens type
0, the only phase-difference AF is executed. When the interchangeable
lens 2 is the lens type 1, the only imager AF is executed. Moreover,
in a case where the interchangeable lens 2 is the lens type 2, after
coarsely adjusting the focusing control by the phase-difference
AF, the focusing control is finely adjusted by the imager AF.
[0089]Here, a relation between the lens type of the interchangeable
lens 2 and time required for the focusing control will be described.
First, when the user performs the imager AF without feeling any
incompatibility, the time required for the focusing control needs
to be shortened to a certain degree (set to, e.g., one second or
less). This is because, in a case where the time required for the
focusing control is excessively long, a problem occurs that the
opportunity to get the best shot is missed or that a camera user
judges that the camera gets out of order.
[0090]Therefore, when the driving time of the focus lens 3A is
longer than a predetermined time, it is considered that the lens
is not suitable for the imager AF in which the focus lens 3A is
scanned to search for the peak evaluated AF value while the evaluated
AF value is acquired. The lens types are determined based on such
consideration.
[0091]Specifically, it is assumed that the interchangeable lens
having the focus lens driving time not less than the predetermined
time at the whole shooting distance range of an infinitely far point
to the closest point is the lens type 1 or 2 which is the lens suitable
for the imager AF. Moreover, it is assumed that the interchangeable
lens having the focus lens driving time not less than the predetermined
time at the whole shooting distance range of the infinitely far
point to the closest point is the lens type 0 as the lens which
is not suitable for the imager AF.
[0092]Here, examples of the interchangeable lens which is the lens
type 0 include a micro lens having a high shooting magnification
of 1:1 macro or the like and a telephoto lens having a long focal
length. Examples of the lens of the lens type 1 include a wide-angle
lens having a short focal length. Examples of the lens of the lens
type 2 include a standard lens having a medium focal length.
[0093]According to such classification of the lens type, in a case
where, for example, the telephoto lens of the lens type 0 having
the long focal length is used as the interchangeable lens 2, since
the interchangeable lens is not suitable for the imager AF as described
above, the focusing control is performed by the only phase-difference
AF. In a case where, for example, the wide-angle lens of the lens
type 1 having the short focal length is used as the interchangeable
lens 2, when the focus lens is scanned over the whole shooting distance
range by the imager AF, the driving can be completed in a sufficiently
short time. Therefore, the focusing control is performed by the
only highly precise imager AF. Furthermore, in a case where, for
example, the standard lens of the lens type 2 having the intermediate
focal length is used as the interchangeable lens 2, since a long
time is required for the focusing control by the only imager AF
as compared with the lens type 1, the coarse adjustment is performed
by the phase-difference AF, and the fine adjustment is performed
by the imager AF. In consequence, the time of the focusing control
is compatible with the precision.
[0094]The focus detecting operation performed by the imager AF
in the step S110 will hereinafter be described with reference to
a flow chart of FIG. 10.
[0095]First, it is judged whether or not the in-range flag has
been set in the step S130 (step S200). Here, in a case where it
is judged that the in-range flag has been set, a scan region of
the imager AF is set (step S201). Here, the scan region is set to
.DELTA.X before or after a current position of the focus lens 3A
which is regarded as the center position. This .DELTA.X is the scan
region predetermined so as to perform a sufficiently highly precise
focusing operation at a high speed. The range is stored in the storage
section 5A of the interchangeable lens 2 and read out for use by
the control section 16. It is to be noted that the above .DELTA.X
is appropriately changed with a parameter such as the focal length
of the interchangeable lens 2, the position (a distance) of the
focus lens 3A or high reliability of the phase difference detection.
[0096]In a case where it is judged in the step S200 that the in-range
flag is not set, the scan region of the focus lens 3A is set to
the whole focus lens movable region, that is, a region from the
closest point to the infinitely far point (step S202). In the processing
of this step S202, it is considered that there is a high possibility
that the focus lens 3A is not positioned in the vicinity of the
focus because the phase difference cannot reliably be detected or
the phase-difference AF is not executed in advance.
[0097]After transmitting the scan region set in the step S201 or
S202 in this manner to the lens control section 5 by the body and
lens communication, a predetermined command is transmitted to the
lens control section 5 to control the lens driving section 4 via
the lens control section 5. In consequence, the focus lens 3A is
moved to an end of the scan region on a side close to the camera
body 1 (step S203).
[0098]Moreover, the lens driving command of the imager AF is transmitted
to the lens control section 5 to start a scan operation of the focus
lens 3A (step S204). Furthermore, the image processing section 13
exposes (EXP) the image pickup device 7 and reads out (READ) the
image data at a predetermined timing after generation of the vertical
sync signal VD. In addition, the evaluated AF value of the imager
AF is calculated based on this read image data (step S205).
[0099]Subsequently, the processing waits until the vertical sync
signal VD from the image processing section 13 rises (step S206).
When the rising of the vertical sync signal VD is detected, the
lens position of the focus lens 3A transmitted from the lens control
section 5 is received (step S207). Moreover, the evaluated AF value
acquired in the step S205 and the lens position of the focus lens
3A acquired in the step S207 are stored as the evaluated AF coordinate
values in a storage section (not shown) (step S208). It is to be
noted that such a relation between the lens position of the focus
lens 3A and the evaluated AF value has been described above with
reference to FIG. 3.
[0100]Subsequently, it is judged with reference to the evaluated
AF coordinate value whether or not a focused point (the peak value
of the evaluated AF value) has been passed (step S209). In a case
where it is judged in this step S209 that the focused point (the
peak value of the evaluated AF value) is not passed, it is judged
whether or not the scan region set in the step S201 or S202 has
all been scanned (step S210). In a case where it is judged in this
step S210 that all the scan region has been scanned, a region to
be scanned remains. Therefore, the processing returns to the step
S205.
[0101]It is to be noted that in a loop of the steps S205 to S210,
the focus lens 3A continues to be driven. When the processing of
the steps S205 to S210 is repeated, the peak value of the imager
AF can be searched.
[0102]In addition, in a case where it is judged in the step S209
that the focused point (the peak value of the evaluated AF value)
is passed, a command to stop the driving of the focus lens 3A is
transmitted to the lens control section 5 by the body and lens communication,
and the driving of the focus lens 3A is stopped (step S211).
[0103]Subsequently, the lens position of the focus lens 3A at the
time when the evaluated AF value reaches the peak value is obtained
in detail by the interpolation with reference to the evaluated AF
coordinate value. Moreover, the lens driving section 4 moves the
focus lens 3A to a position where the evaluated AF value reaches
the peak value via the lens control section 5 by the body and lens
communication (step S212).
[0104]Subsequently, the peak value of the evaluated AF value is
stored as a result of the imager AF in the storage section (not
shown) (step S213) to end the processing of the imager AF. The processing
returns to a main routine of the flow chart shown in FIG. 8. In
addition, in a case where it is judged in the step S210 that all
the scan region has been scanned, the focused point (the peak value
of the evaluated AF value) is not obtained (branched from the step
S209 to NO), and the processing in the scan region ends (branched
from the step S210 to NO). Therefore, the focus lens 3A is moved
to an initial position of the scan region (step S214). Moreover,
the storage section (not shown) stores that the imager AF cannot
be detected to end the processing. The processing returns to the
main routine of the flow chart shown in FIG. 8.
[0105]The operation control of the interchangeable lens 2 by the
lens control section 5 will hereinafter be described with reference
to a flow chart shown in FIG. 11.
[0106]First, when the power source (not shown) of the camera body
1 is turned on, the lens power source is supplied to the interchangeable
lens 2 via the lens contact section 8 from a camera body side. The
lens power source is supplied to the interchangeable lens 2 to initialize
each section of the interchangeable lens 2, and the lens control
section 5 can be operated. Moreover, the processing waits until
there is a request for the body and lens communication from the
control section 16 (step S300). Here, when the demand for the body
and lens communication is generated from the control section 16,
the body and lens communication is performed, and a command transmitted
from the control section 16 is received (step S301).
[0107]Next, it is judged whether or not the imager AF lens driving
command (represented by an IAF lens driving command in FIG. 11)
which is the lens driving command of the imager AF has been received
(step S302). In a case where it is judged in this step S302 that
the imager AF lens driving command has been received, the lens driving
of the focus lens 3A is executed by the lens driving section 4 based
on the imager AF lens driving command (step S309). It is to be noted
that this step S309 corresponds to the step S204 (lens movement
start) shown in FIG. 10.
[0108]After the lens driving is started in the step S309, the processing
waits until the signal VDP output from the control section 16 to
the lens control section 5 via the lens contact section 8 and synchronized
with the vertical sync signal VD falls (step S310). Here, when it
is detected that the signal VDP falls, output data of the encoder
15 indicating the lens position of the focus lens 3A is acquired
(step S311). Moreover, the processing waits until the signal VDP
rises (step S312). Here, when it is detected that the signal VDP
rises, the lens position of the focus lens 3A acquired in the step
S311 is transmitted to the control section 16 (step S313).
[0109]Subsequently, it is judged whether or not a lens stop command
which is a command to stop the driving of the focus lens 3A has
been received (step S314). In a case where it is judged in this
step S314 that the lens stop command has been received, the lens
driving section 4 stops the driving of the focus lens 3A (step S315).
Moreover, the processing returns to the step S300. On the other
hand, in a case where it is judged in the step S314 that the lens
stop command is not received, the processing returns to the step
S310. Subsequently, the processing of the steps S310 to S314 is
repeated until it is judged in the step S314 that the lens stop
command has been received.
[0110]In addition, in a case where it is judged in the step S302
that the imager AF lens driving command has not been received, it
is judged whether or not the lens driving command of the TTL phase-difference
AF has been received (step S303). In a case where it is judged in
this step S303 that the lens driving command of the TTL phase-difference
AF has been received, the lens driving section 4 drives the focus
lens 3A based on the lens driving amount and the driving direction
included in the lens driving command of the TTL phase-difference
AF (step S306). When the lens driving of this step S306 ends, a
lens driving end notice is transmitted to the control section 16
(step S307). Subsequently, the processing returns to the step S300.
[0111]On the other hand, in a case where it is judged in the step
303 that the lens driving command of the TTL phase-difference AF
is not received, it is judged whether or not an initial communication
command has been received (step S304). In a case where it is judged
in this step S304 that the initial communication command has been
received, initial body and lens communication is performed (step
S308).
[0112]It is to be noted that during the body and lens communication
performed in the step S308, the processing communicates with the
control section 16 of the camera body 1 to perform initial setting
of the interchangeable lens 2. Moreover, various data stored in
the interchangeable lens 2 are transmitted to the control section
16.
[0113]It is to be noted that examples of the data stored in the
interchangeable lens 2 include information such as the lens type,
the focal length, the shootable distance, the total number of the
focus pulses and the motor type and various corrected values concerning
the AF. After ending the processing of the step S308, the processing
returns to the step S300.
[0114]Moreover, in a case where it is judged in the step S304 that
the initial communication command is not received, it is judged
whether or not a command other than the above command has been received,
and an operation is executed in response to the command (step S305).
[0115]Timings of operation control during the imager AF will hereinafter
be described with reference to a timing chart shown in FIG. 12.
It is to be noted that the processing of the step S110 (the imager
AF) of the flow chart shown in FIG. 8 indicates a series of processing
of the flow chart shown in FIG. 10.
[0116]First, in the step S204 of the flow chart shown in FIG. 10,
the control section 16 transmits the imager AF lens driving command
to the lens control section 5. Moreover, the lens control section
5 receives the imager AF lens driving command. In the step S309
of the flow chart shown in FIG. 11, the lens driving section 4 starts
the lens driving of the focus lens 3A.
[0117]On the other hand, the encoder 15 generates a signal pulse
which is an encoder signal with the movement of the focus lens 3A.
Moreover, the lens control section 5 counts the signal pulses to
acquire the lens position of the focus lens 3A.
[0118]It is to be noted that, as seen from the timing chart shown
in FIG. 12, the control section 16 continuously drives the focus
lens 3A. In the camera body 1, the imaging operation of the image
pickup device 7 is performed at a predetermined timing of the vertical
sync signal VD generated by the image processing section 13.
[0119]Moreover, when the exposure (EXP of the image pickup device
7 operation timing chart shown in FIG. 12) of the image pickup device
7 ends, the image data of the image pickup device 7 is read out
by the image processing section 13 (READ of the image pickup device
7 timing chart shown in FIG. 12). In parallel with this readout
operation, the image processing section 13 calculates the evaluated
AF value (IAF) (the step S205 of the flow chart shown in FIG. 10).
It is to be noted that the end timing of the calculation of the
evaluated AF value is set beforehand so that the calculation ends
before the vertical sync signal VD rises.
[0120]Moreover, when the lens control section 5 waits until the
signal VDP falls (the step S310 of the flow chart shown in FIG.
11) and detects the falling of the signal VDP, the section acquires
the data of the lens position of the focus lens 3A from the pulse
count output of the encoder 15 (FIG. 11: step S311).
[0121]Subsequently, when the lens control section 5 waits until
the signal VDP (the vertical sync signal VD) rises (FIG. 11: step
S312) and detects the rising of the signal VDP, the section transmits
the data of the lens position of the focus lens 3A acquired as described
above to the control section 16 (FIG. 11: step S313).
[0122]In other words, when the control section 16 waits until the
vertical sync signal VD rises (FIG. 10: step S206) and detects the
rising of the vertical sync signal VD, the section receives the
lens position transmitted from the lens control section 5 (FIG.
10: step S207).
[0123]As described above, the control section 16 performs the body
and lens communication with the lens control section 5 in synchronization
with the rising of the vertical sync signal VD. In consequence,
the data of the lens position of the focus lens 3A during the falling
of the vertical sync signal VD can be acquired.
[0124]It is to be noted that a series of operations including the
exposure operation of the image pickup device 7 to the transmission
operation of the data of the lens position of the focus lens 3A
to the control section 16 by the lens control section 5 are repeatedly
executed during the driving of the photographing lens system 3 while
the imager AF operation is performed.
[0125]Moreover, when the control section 16 transmits the lens
stop command to the lens control section 5 by the body and lens
communication, the lens control section 5 allows the lens driving
section 4 to stop the driving of the focus lens 3A (FIG. 11: step
S315).
[0126]As described above, according to the first embodiment, there
can be provided the digital camera and the camera system capable
of performing the highly precisely focusing control at the high
speed regardless of optical characteristics of the interchangeable
lens for use and a focus lens driving mechanism.
[0127]Specifically, lens type data such as whether or not the interchangeable
lens 2 is suitable for the TTL phase-difference AF and/or the imager
AF is stored beforehand in the interchangeable lens 2. Moreover,
it is judged on a camera body 1 side based on the lens type data
whether or not the interchangeable lens 2 for actual use is suitable
for the TTL phase-difference AF and/or the imager AF. Here, in a
case where it is judged that the interchangeable lens 2 for actual
use is suitable for the TTL phase-difference AF, the focusing control
is performed by the TTL phase-difference AF. In a case where it
is judged that the interchangeable lens 2 for actual use is suitable
for the imager AF, the focusing control is performed by the imager
AF. Moreover, in a case where it is judged that the interchangeable
lens 2 for actual use is suitable for both of the TTL phase-difference
AF and the imager AF, the focusing control is coarsely adjusted
by the TTL phase-difference AF system. Subsequently, the focusing
control is finely adjusted by the imager AF. As described above,
the optimum automatic focusing method is automatically selected
in accordance with the optical characteristics of the interchangeable
lens 2 for actual use and the focusing control mechanism to perform
the focusing control. In consequence, the highly precisely focusing
control can be performed at the high speed.
Second Embodiment
[0128]Next, a digital camera and a camera system according to a
second embodiment of the present invention will be described. It
is to be noted that only contents different from those of the digital
camera and the camera system according to the first embodiment will
be described.
[0129]Operation control performed by a control section 16 of the
digital camera according to the second embodiment will hereinafter
be described with reference to a flow chart shown in FIG. 13.
[0130]First, when a user turns on a power source (not shown) disposed
in a camera body 1, the control section 16 of the camera body 1
performs body and lens communication (step S400). That is, in this
step S400, the control section 16 reads out various data stored
in a storage section 5A of an interchangeable lens 2, and stores
the data in a storage section (not shown) of the control section
16.
[0131]Moreover, examples of the data concerning the interchangeable
lens 2 to be communicated during this body and lens communication
include information such as the total number of focus pulses (hereinafter
referred to as the total number of the lens pulses) corresponding
to the whole shooting distance range of the interchangeable lens
2, a focus lens driving speed (hereinafter referred to as the lens
speed), a focal length, a shootable distance and a driving motor
type and various corrected values concerning AF. It is to be noted
that in the second embodiment, the focus lens driving speed is grasped
as the number of driving pulses per unit time.
[0132]After ending the body and lens communication in the step
S400, the user half presses a release button to wait until a release
switch 18 (1RSW) is turned on (step S401). Moreover, when the 1RSW
is turned on, the step S401 is branched to YES to judge lens data
of the interchangeable lens 2 based on the data acquired during
the initial body and lens communication of the step S400 (step S402).
Specifically, during the judgment of the lens data in this step
S402, the lens data is judged based on data of the total number
of the lens pulses and the lens speed, and the judgment result is
stored in the storage section (not shown) disposed in the control
section 16.
[0133]Subsequently, it is judged whether or not the total number
of the lens pulses is smaller than a predetermined value A (step
S403). In a case where it is judged in this step S403 that the total
number of the lens pulses is smaller than the predetermined value
A, it is judged whether or not the lens speed is larger than a predetermined
value V (step S404). In a case where it is judged in this step S404
that the lens speed is not larger than the predetermined value V,
processing of steps S405 to S414 and steps S430, S431 and S432 is
performed. Here, the steps S405 to S414 are steps which perform
processing similar to that of the steps S105 to S114 of the first
embodiment. Moreover, the steps S430, S431 and S432 are steps which
perform processing similar to that of the steps S130, S131 and S132
of the first embodiment. Furthermore, after ending the processing
of the step S432, the processing returns to the step S401. In a
case where it is judged in the step S404 that the lens speed is
larger than the predetermined value V, the processing advances to
the step S410. In addition, in a case where it is judged in the
step S403 that the total number of the lens pulses is not smaller
than the predetermined value A, processing of steps S415 to S421
is performed. Here, the steps S415 to S421 are steps which perform
processing similar to that of the steps S115 to S121 of the first
embodiment. Moreover, after ending the processing of the step S420
or S421, the processing shifts to a shooting sequence of the step
S414.
[0134]As described above, in the digital camera and the camera
system according to the second embodiment, in a case where the total
number of the lens pulses is larger than the predetermined value
A, only TTL phase-difference AF is executed. In a case where the
total number of the lens pulses is smaller than the predetermined
value A and the lens speed is larger than the predetermined value
V, only imager AF is executed. Moreover, in a case where the total
number of the lens pulses is smaller than the predetermined value
A and the lens speed is smaller than the predetermined value V,
focusing control is coarsely adjusted by the TTL phase-difference
AF, and the focusing control is finely adjusted by imager AF.
[0135]As described above, according to the second embodiment, there
can be provided a digital camera and a camera system which produce
effects equivalent to those of the first embodiment.
[0136]That is, in the second embodiment, whether or not the interchangeable
lens 2 is an interchangeable lens suitable for the TTL phase-difference
AF or the imager AF is judged by use of parameters such as the total
number of the lens pulses which is the total number of the focus
pulses corresponding to the whole shooting distance range of the
interchangeable lens 2 and the lens speed which is the focus lens
driving speed. Here, in a case where it is judged that the interchangeable
lens 2 is suitable for the TTL phase-difference AF, the focusing
control is performed by the TTL phase-difference AF. In a case where
it is judged that the interchangeable lens 2 is suitable for the
imager AF, the focusing control is performed by the imager AF. Moreover,
in a case where it is judged that the interchangeable lens 2 is
suitable for both of the TTL phase-difference AF and the imager
AF, the focusing control is coarsely adjusted by the TTL phase-difference
AF system. Subsequently, the focusing control is finely adjusted
by the imager AF. As described above, the optimum automatic focusing
method is automatically selected in accordance with optical characteristics
of the interchangeable lens 2 and a focusing control mechanism to
perform the focusing control. In consequence, the highly precisely
focusing control can be performed at the high speed.
ALTERNATIVE EXAMPLE
[0137]It is to be noted that instead of setting parameters such
as the total number of lens pulses which is the total number of
focus pulses corresponding the whole shooting distance range of
a interchangeable lens 2 and a lens speed which is a movement speed
of a focus lens 3A, needless to say, a numeric value (the total
number of the lens pulses/the lens speed) obtained by dividing the
total number of the lens pulses by the lens speed may be set as
the parameter.
[0138]Here, the numeric value obtained by dividing the total number
of the lens pulses by the lens speed is a parameter which is proportional
to a lens driving time, that is, time required for focusing control.
Therefore, even if the numeric value obtained by dividing this total
number of the lens pulses by the lens speed is used, length of a
focusing control time can be judged.
Third Embodiment
[0139]Next, a digital camera and a camera system according to a
third embodiment of the present invention will be described. It
is to be noted that only contents different from those of the first
embodiment will be described.
[0140]Operation control performed by a control section 16 of the
digital camera according to the third embodiment will hereinafter
be described with reference to a flow chart shown in FIG. 14.
[0141]First, when a user turns on a power source (not shown) disposed
in a camera body 1, the control section 16 of the camera body 1
performs body and lens communication (step S500). That is, in this
step S500, the control section 16 reads out various data stored
in a storage section 5A of an interchangeable lens 2, and stores
the data in a storage section (not shown) of the control section
16. Moreover, examples of the data concerning the interchangeable
lens 2 to be communicated during this body and lens communication
include information such as a shootable focal length corresponding
to the whole shooting region of the interchangeable lens 2 and a
driving motor type and various corrected values concerning AF.
[0142]After ending the body and lens communication in the step
S500, the user half presses a release button to wait until a release
switch 18 (1RSW) is turned on (step S501). Moreover, when the 1RSW
is not turned on, the body and lens communication is performed to
acquire a state of the interchangeable lens 2 (step S523), and the
processing returns to the step S501. It is to be noted that, when
the interchangeable lens 2 is, for example, an interchangeable lens
of a zooming type, examples of the information of the interchangeable
lens 2 acquired in the step S523 include a focal length value in
a case zooming is performed to change a focal length. In a case
where the interchangeable lens 2 is an interchangeable lens having
a function capable of limiting a shootable distance range, the examples
of the information include the smallest distance value in a case
where the smallest distance is changed.
[0143]In addition, in a case where it is judged in the step S501
that the 1RSW has been turned on, the lens data of the interchangeable
lens 2 is judged based on data acquired during the initial body
and lens communication of the step S500 (step S502).
[0144]Specifically, during the lens data judgment of the step S502,
the judgment is performed based on data of the smallest shootable
distance of the interchangeable lens 2, the focal length and the
type of the motor which drives a focus lens 3A. The judgment result
is stored in the storage section (not shown) disposed in the control
section 16.
[0145]After ending the data judgment processing of the step S502,
it is judged whether or not the smallest shootable distance of the
interchangeable lens 2 is smaller than a predetermined value L (step
S503). In a case where it is judged in this step S503 that the smallest
shootable distance of the interchangeable lens 2 is smaller than
the predetermined value L, it is judged whether or not the focal
length of the interchangeable lens 2 is smaller than a predetermined
value f (step S504). In a case where it is judged in this step S504
that the focal length of the interchangeable lens 2 is smaller than
the predetermined value f, the processing advances to step S511
described later.
[0146]On the other hand, in a case where it is judged in the step
S504 that the focal length of the interchangeable lens 2 is not
smaller than the predetermined value f, it is judged whether or
not a driving source included in a lens driving section 4 is a stepping
motor (step S505).
[0147]It is to be noted that driving source data for judgment of
a driving source in the step S505 is set as shown in, for example,
FIG. 15. That is, lens driving source data (0, 1 or 2) is data indicating
that the driving source is a DC motor, a stepping motor or an ultrasonic
motor.
[0148]In a case where it is judged in the step S505 that the driving
source included in the lens driving section 4 is the stepping motor,
the processing advances to the step S511 described later. On the
other hand, in a case where it is judged in the step S505 that the
driving source included in the lens driving section 4 is not the
stepping motor, processing of steps S506 to S515 and steps S530,
S531 and S532 is performed.
[0149]Here, the steps S506 to S515 are steps which perform processing
similar to that of the steps S405 to S414 of the second embodiment.
Moreover, the steps S530 to S532 are steps which perform processing
similar to that of the steps S430 to S432 of the second embodiment.
[0150]In addition, in a case where it is judged in the step S503
that the smallest shootable distance of the interchangeable lens
2 is not smaller than the predetermined value L, processing of steps
S516 to S522 is performed. Here, the steps S516 to S522 are steps
which perform processing similar to that of the steps S115 to S121
of the first embodiment.
[0151]It is to be noted that in the step S521, focusing display
indicating that a focused state is obtained is displayed in an LCD
panel 10 by an image processing section 13. Subsequently, in the
step S522, display indicating that the lens has a non-focused state
is displayed in the LCD panel 10 by the image processing section
13. Subsequently, the processing shifts to a shooting sequence of
the step S515.
[0152]As described above, in the digital camera and the camera
system according to the third embodiment, in a case where the smallest
shootable distance of the interchangeable lens 2 is larger than
the predetermined value L, only TTL phase-difference AF is executed.
In a case where the smallest shootable distance of the interchangeable
lens 2 is smaller than the predetermined value L and the focal length
is smaller than the predetermined value f, and in a case where the
smallest shootable distance of the interchangeable lens 2 is smaller
than the predetermined value L, the focal length is larger than
the predetermined value f and the stepping motor is used as the
driving source of the focus lens 3A, only imager AF is executed.
Moreover, in a case where the smallest shootable distance of the
interchangeable lens 2 is smaller than the predetermined value L,
the focal length is larger than the predetermined value f and a
motor other than the stepping motor is used as the driving source
of the focus lens 3A, focusing control is coarsely adjusted by the
TTL phase-difference AF, and the focusing control is finely adjusted
by imager AF.
[0153]It is to be noted that even in a case where an interchangeable
lens of such a zooming type that the focal length is variable as
described above, an interchangeable lens of such a type that the
smallest distance changes with the zooming or an interchangeable
lens having a function capable of changing the shootable distance
range is used as the interchangeable lens 2, the latest state of
the interchangeable lens 2 is acquired in the step S523. Therefore,
the focal length and the smallest distance during the AF are necessarily
reflected in the judgment of the steps S503 and S504.
[0154]As described above, according to the third embodiment, there
can be provided a digital camera and a camera system which produce
effects equivalent to those of the first embodiment.
[0155]That is, in the third embodiment, whether or not the interchangeable
lens 2 is an interchangeable lens suitable for the TTL phase-difference
AF or the imager AF is judged by use of parameters such as the smallest
shootable distance of the interchangeable lens 2, the focal length
and the type of the driving motor of the focus lens 3A.
[0156]Here, in a case where it is judged that the interchangeable
lens 2 is suitable for the TTL phase-difference AF, the focusing
control is performed by the TTL phase-difference AF. In a case where
it is judged that the interchangeable lens 2 is suitable for the
imager AF, the focusing control is performed by the imager AF. Moreover,
in a case where it is judged that the interchangeable lens 2 is
suitable for both of the TTL phase-difference AF and the imager
AF, the focusing control is coarsely adjusted by the TTL phase-difference
AF system. Subsequently, the focusing control is finely adjusted
by the imager AF. As described above, the optimum automatic focusing
method is automatically selected in accordance with optical characteristics
of the interchangeable lens 2 and a focusing control mechanism to
perform the focusing control. In consequence, the highly precisely
focusing control can be performed at the high speed.
[0157]It is to be noted that even if a shooting magnification is
used as the judgment parameter instead of the smallest shootable
distance of the interchangeable lens 2, needless to say, a similar
effect is obtained.
Fourth Embodiment
[0158]Next, a digital camera and a camera system according to a
fourth embodiment of the present invention will be described. It
is to be noted that only contents different from those of the first
embodiment will be described.
[0159]Operation control performed by a control section 16 of the
digital camera according to the fourth embodiment will hereinafter
be described with reference to a flow chart shown in FIG. 16.
[0160]First, when a user turns on a power source (not shown) disposed
in a camera body 1, the control section 16 of the camera body 1
performs body and lens communication (step S600). That is, in this
step S600, the control section 16 reads out various data stored
in a storage section 5A of an interchangeable lens 2, and stores
the data in a storage section (not shown) of the control section
16.
[0161]It is to be noted that examples of the data concerning the
interchangeable lens 2 to be communicated during this body and lens
communication include information indicating whether or not an accessory
such as a telephoto converter, a wide converter or a extension tube
(a close-up ring) is attached to the interchangeable lens 2. The
attachment of this accessory can be detected with an electric contact
disposed at, for example, the interchangeable lens 2. This attachment
information can be stored in the storage section 5A of the interchangeable
lens 2. Based on this attachment information, the control section
16 as a judgment section of the camera body 1 judges the accessory
which is attached to the interchangeable lens.
[0162]After ending the body and lens communication in the step
S600, the user half presses a release button to wait until a release
switch 18 (1RSW) is turned on (step S601). Here, when the 1RSW is
not turned on, the body and lens communication is performed to acquire
information of the interchangeable lens 2 (step S623), and the processing
returns to the step S601.
[0163]It is to be noted that, when the interchangeable lens 2 is,
for example, an interchangeable lens of a zooming type, examples
of the information of the interchangeable lens 2 acquired in the
step S623 include a focal length value in a case zooming is performed
to change a focal length. In a case where the interchangeable lens
2 is an interchangeable lens having a function capable of limiting
a shootable distance range, the examples of the information include
the smallest distance value in a case where the smallest distance
is changed.
[0164]Moreover, in a case where it is judged in the step S601 that
the 1RSW has been turned on, lens data of the interchangeable lens
2 is judged based on data acquired during the initial body and lens
communication of the step S600 (step S602).
[0165]Specifically, during the lens data judgment of the step S602,
it is judged whether or not an accessory such as the telephoto converter,
the wide converter or the extension tube (the close-up ring) is
attached to the interchangeable lens 2. The judgment result is stored
in a storage section disposed in the control section 16.
[0166]After ending the lens data judgment processing of the step
S602, it is judged whether or not the wide converter is attached
to the interchangeable lens 2 (step S603). In a case where it is
judged in this step S603 that the wide converter is attached to
the interchangeable lens 2, the processing advances to step S611
described later.
[0167]In a case where it is judged in the step S603 that the wide
converter is not attached to the interchangeable lens 2, it is judged
whether or not the extension tube is attached to the interchangeable
lens 2 (step S604). In a case where it is judged in this step S604
that the extension tube is attached to the interchangeable lens
2, the processing advances to step S606 described later.
[0168]In a case where it is judged in the step S604 that the extension
tube is not attached to the interchangeable lens 2, it is judged
whether or not the telephoto converter is attached to the interchangeable
lens 2 (step S605). In a case where it is judged in this step S605
that the telephoto converter is not attached to the interchangeable
lens 2, the processing advances to the step S606 described later.
[0169]In a case where it is judged in the step S605 that the telephoto
converter is attached to the interchangeable lens 2, processing
of steps S616 to S622 is performed. Here, the steps S616 to S622
are steps which perform processing similar to that of the steps
S115 to S121 of the first embodiment.
[0170]It is to be noted that in the step S621, focusing display
indicating that a focused state is obtained is displayed in an LCD
panel 10 by an image processing section 13. Subsequently, in the
step S622, display indicating that the lens has a non-focused state
is displayed in the LCD panel 10 by the image processing section
13. Subsequently, the processing shifts to a shooting sequence of
step S615 which performs processing similar to that of the step
S515.
[0171]In addition, in a case where it is judged in the step S604
that the extension tube is attached to the interchangeable lens
2 and it is judged in the step S605 that the telephoto converter
is not attached to the interchangeable lens 2, processing of steps
S606 to S615 and steps S630 to S632 is performed. Here, the steps
S606 to S615 are steps which perform processing similar to that
of the steps S105 to S114 of the first embodiment. The steps S630
to S632 are steps which perform processing similar to that of the
steps S130 to S132, respectively. After ending the processing of
the step S632, the processing returns to the step S601.
[0172]It is to be noted that in a case where it is judged in the
step S603 that the wide converter is attached to the interchangeable
lens 2, the processing advances to the step S611 which performs
processing similar to that of the step S110 of the first embodiment
to execute imager AF. Specific processing contents during this imager
AF have been described in detail with reference to the flow chart
shown in FIG. 10.
[0173]As described above, in the digital camera and the camera
system according to the fourth embodiment, when the wide converter
is attached to the interchangeable lens 2, the only imager AF is
executed. When the wide converter is attached to the interchangeable
lens 2, the focal length of the interchangeable lens 2 is converted
into a shorter focal length. Therefore, a focusing control time
does not change, a subject depth increases, and focusing control
precision changes to be high. Therefore, it is more appropriate
to use the imager AF which is more highly precise than TTL phase-difference
AF. When the telephoto converter is attached to the interchangeable
lens 2, the only TTL phase-difference AF is executed. Since the
focal length of the interchangeable lens 2 is converted into a longer
focal length, an evaluated AF value (contrast) less changes with
respect to a change of a predetermined defocus amount. This is disadvantageous
for the imager AF. Moreover, in a case where the extension tube
is attached to the interchangeable lens 2, after coarsely adjusting
focusing control by the TTL phase-difference AF, the focusing control
is finely adjusted by the imager AF. This is because, when the extension
tube is attached to the interchangeable lens 2, a relation between
the defocus amount and a lens movement amount changes, the precision
of the focusing control by the TTL phase-difference AF drops, and
time required for focusing lengthens. Therefore, in such a case,
the TTL phase-difference AF is used during the only coarse adjustment.
Subsequently, the fine adjustment is performed by the imager AF
in which any precision drop is not generated.
[0174]As described above, according to the fourth embodiment, there
can be provided a digital camera and a camera system which produce
effects equivalent to those of the first embodiment.
[0175]That is, in the fourth embodiment, whether or not the interchangeable
lens 2 has a state suitable for the TTL phase-difference AF or the
imager AF is judged by use of parameters such as whether or not
an accessory such as the wide converter, the extension tube or the
telephoto converter is attached to the interchangeable lens 2. Here,
in a case where it is judged that the interchangeable lens 2 is
suitable for the TTL phase-difference AF, the focusing control is
performed by the TTL phase-difference AF. In a case where it is
judged that the interchangeable lens 2 is suitable for the imager
AF, the focusing control is performed by the imager AF. Moreover,
in a case where it is judged that the interchangeable lens 2 is
suitable for both of the TTL phase-difference AF and the imager
AF, the focusing control is coarsely adjusted by the TTL phase-difference
AF system. Subsequently, the focusing control is finely adjusted
by the imager AF. As described above, the optimum automatic focusing
method is automatically selected in accordance with optical characteristics
of the interchangeable lens 2 and a focusing control mechanism to
perform the focusing control. In consequence, the highly precisely
focusing control can be performed at the high speed.
[0176]While there has been shown and described what are considered
to be preferred embodiments of the invention, it will, of course,
be understood that various modifications and changes in form or
detail could readily be made without departing from the spirit of
the invention. It is therefore intended that the invention not be
limited to the exact forms described and illustrated, but constructed
to cover all modifications that may fall within the scope of the
appended claims. |