U.S. patent application number 11/381887 was filed with the patent office on 2006-08-24 for optical apparatus operable in static and dynamic image taking modes.
This patent application is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Koji Hoshi, Takeshi Koyama.
Application Number | 20060188245 11/381887 |
Document ID | / |
Family ID | 27481741 |
Filed Date | 2006-08-24 |
United States Patent
Application |
20060188245 |
Kind Code |
A1 |
Koyama; Takeshi ; et
al. |
August 24, 2006 |
OPTICAL APPARATUS OPERABLE IN STATIC AND DYNAMIC IMAGE TAKING
MODES
Abstract
An optical apparatus including a photographic optical unit
including a movable optical component for varying a focal length, a
light amount adjusting unit disposed in an optical path of the
photographic optical unit, the light amount adjusting unit varying
an aperture to adjust an amount of light and changing an F-number
by varying the aperture, an image pickup device for picking up an
optical image formed by the photographic optical unit, a mode
switching member for selecting a dynamic image taking mode and a
static image taking mode, and a controller. The controller sets
different values of the F-number of the light amount adjusting unit
in accordance with a state selected by the mode switching member,
or varies a moving range of the movable optical component in
accordance with a state selected by the mode switching member.
Inventors: |
Koyama; Takeshi; (Toshigi,
JP) ; Hoshi; Koji; (Tochigi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
Canon Kabushiki Kaisha
Tokyo
JP
|
Family ID: |
27481741 |
Appl. No.: |
11/381887 |
Filed: |
May 5, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09978048 |
Oct 17, 2001 |
|
|
|
11381887 |
May 5, 2006 |
|
|
|
Current U.S.
Class: |
396/257 ;
348/345; 348/E5.04 |
Current CPC
Class: |
H04N 5/238 20130101 |
Class at
Publication: |
396/257 ;
348/345 |
International
Class: |
G03B 7/095 20060101
G03B007/095; G03B 13/00 20060101 G03B013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2000 |
JP |
2000-327096 |
Oct 26, 2000 |
JP |
2000-327095 |
Oct 26, 2000 |
JP |
2000-327094 |
Jan 9, 2001 |
JP |
2001-001938 |
Claims
1-8. (canceled)
9. An optical apparatus, comprising: a photographic optical unit
including a variable power optical component moving along an
optical axis to perform a variable power operation; an image pickup
device for picking up an optical image formed by said photographic
optical unit; a mode switching member for selecting a dynamic image
taking mode and a static image taking mode; and a controller for
controlling a movement of said variable power optical component of
said photographic optical unit, wherein said controller varies a
variable power range of said variable power optical component in
accordance with a state selected by said mode switching member.
10. The optical apparatus according to claim 9, wherein said
controller controls a movement of said variable power optical
component in a range from a wide end to a tele end when a state
selected by said mode switching member is said dynamic image taking
mode, and said controller controls a movement of said variable
power optical component in a range from a position shifted somewhat
to said tele side from said wide end to said tele end when a state
selected by said mode switching member is said static image taking
mode.
11-12. (canceled)
13. An optical apparatus, comprising: a photographic optical unit
including a movable optical component moving along an optical axis;
an image pickup device for picking up an optical image formed by
said photographic optical unit; a mode switching member for
selecting a dynamic image taking mode and a static image taking
mode; and a controller for controlling a movement of said movable
optical component of said photographic optical unit, wherein said
controller varies a moving range of said movable optical component
in accordance with a state selected by said mode switching
member.
14. An optical apparatus, comprising: a photographic optical unit
including a movable optical component; an image pickup device for
picking up an optical image formed by said photographic optical
unit; a mode switching member for selecting a dynamic image taking
mode and a static image taking mode; and a controller for
controlling a movable operation of said optical component of said
photographic optical unit, wherein said controller varies a movable
range of said optical component in accordance with a state selected
by said mode switching member.
15-21. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an optical apparatus
capable of taking both dynamic images and static images for use in
an image pickup device or the like.
[0003] 2. Description of the Related Art
[0004] As one of cameras capable of taking both dynamic images and
static images, an available camera has a CCD image pickup device
for taking dynamic images and allows a silver halide film to be
loaded thereinto for taking static images.
[0005] The camera is configured such that luminous flux through
photographic lenses is divided on an optical path, one divided
luminous flux is provided for forming an image on the CCD image
pickup device through a reduction optical system and the other
divided luminous flux is provided for forming an image on the
silver halide film with a larger picture size than the CCD. Such a
camera not only can take dynamic images, but also can achieve high
picture quality unique to the silver halide film in taking static
images.
[0006] As another camera capable of taking both dynamic images and
static images, a proposed video camera uses photographic lenses and
a CCD image pickup device in common for taking dynamic images and
static images.
[0007] The camera using either the CCD image pickup device or the
silver halide film as required to take dynamic images or static
images, however, has a problem of an increased size of the camera
due to the need of a luminous flux dividing means as mentioned
above.
[0008] On the other hand, the video camera using the photographic
lenses and the CCD image pickup device in common for taking dynamic
images and static images cannot provide satisfactorily high-quality
static images since it can offer, at the best, quality provided
when it uses one of images taken successively in a predetermined
time period in taking dynamic images as a static image.
[0009] When lenses can be more favorably corrected for aberration
to obtain high-quality static images, the lens system and thus the
entire camera tend to be increased in size. A simple increase in
the number of pixels in the CCD means the use of an excessively
high number of pixels over a level required in taking dynamic
images, resulting in an overload imposed on dynamic image
circuitry.
SUMMARY OF THE INVENTION
[0010] To address the problems, it is an object of the present
invention to provide an optical apparatus capable of taking dynamic
images with a lighter load on dynamic image processing and taking
static images with high image quality while the camera has a small
size.
[0011] To achieve the aforementioned object, an optical apparatus
according to the present invention comprises:
[0012] a taking optical unit having a fixed focal length;
[0013] a light amount adjusting unit disposed in an optical path of
the taking optical unit, the light amount adjusting unit varying an
aperture to adjust an amount of light and changing an F-number by
varying the aperture;
[0014] an image pickup device for picking up an optical image
formed by the taking optical unit;
[0015] a mode switching member for selecting a dynamic image taking
mode and a static image taking mode; and
[0016] a controller for controlling the variation in the aperture
by the light amount adjusting unit;
[0017] wherein the controller sets different values of the F-number
of the light amount adjusting unit at the fixed focal length of the
taking optical unit in accordance with a state selected by the mode
switching member.
[0018] According to the present invention, an optical apparatus
comprises:
[0019] a taking optical unit including a movable optical component
for varying a focal length;
[0020] a light amount adjusting unit disposed in an optical path of
the taking optical unit, the light amount adjusting unit varying an
aperture to adjust an amount of light and changing an F-number by
varying the aperture;
[0021] an image pickup device for picking up an optical image
formed by the taking optical unit;
[0022] a mode switching member for selecting a dynamic image taking
mode and a static image taking mode; and
[0023] a controller for controlling the variation in the aperture
of the light amount adjusting unit;
[0024] wherein the controller sets different values of the F-number
of the light amount adjusting unit at the same focal length of the
taking optical unit in accordance with a state selected by the mode
switching member.
[0025] According to the present invention, an optical apparatus
comprises:
[0026] a taking optical unit including a zoom optical component
moving along an optical axis to perform a variable power
operation;
[0027] an image pickup device for picking up an optical image
formed by the taking optical unit;
[0028] a mode switching member for selecting a dynamic image taking
mode and a static image taking mode; and
[0029] a controller for controlling a movement of the zoom optical
component of the light amount adjusting unit;
[0030] wherein the controller varies a variable power range of the
zoom optical component in accordance with a state selected by the
mode switching member.
[0031] According to the present invention, an optical apparatus
comprises:
[0032] a taking optical unit having an optical axis;
[0033] an image pickup device for picking up an optical image
formed by the taking optical unit, the image pickup device having a
first image size area for performing image pickup and a second
image size area for performing image pickup including the first
image size area and larger than the first image size area;
[0034] a mode switching member for selecting a dynamic image taking
mode and a static image taking mode; and
[0035] a controller for controlling image pickup of the image
pickup device;
[0036] wherein the controller switches between the first image size
area and the second image size area in accordance with a state
selected by the mode switching member.
[0037] According to the present invention, an optical apparatus
comprises:
[0038] a taking optical unit including a movable optical component
moving along an optical axis;
[0039] an image pickup device for picking up an optical image
formed by the taking optical unit;
[0040] a mode switching member for selecting a dynamic image taking
mode and a static image taking mode; and
[0041] a controller for controlling a movement of the movable
optical component of the taking optical unit;
[0042] wherein the controller varies a moving range of the movable
optical component in accordance with a state selected by the mode
switching member.
[0043] According to the present invention, an optical apparatus
comprises:
[0044] a taking optical unit including a movable optical
component;
[0045] an image pickup device for picking up an optical image
formed by the taking optical unit;
[0046] a mode switching member for selecting a dynamic image taking
mode and a static image taking mode; and
[0047] a controller for controlling a movable operation of the
optical component of the taking optical unit;
[0048] wherein the controller varies a movable range of the optical
component in accordance with a state selected by the mode switching
member.
[0049] According to the present invention, an optical apparatus
comprises;
[0050] a taking optical unit having an optical axis;
[0051] a correcting optical component provided on the optical axis
of the taking optical unit, the correcting optical component being
driven to incline the optical axis for correcting a blur of an
image;
[0052] an image pickup device for picking up an optical image
formed by the taking optical unit, the image pickup device having a
first image size area for performing image pickup and a second
image size area for performing image pickup including the first
image size area and larger than the first image size area;
[0053] a mode switching member for selecting a dynamic image taking
mode and a static image taking mode; and
[0054] a controller for controlling image pickup of the image
pickup device;
[0055] wherein, when the correcting optical component is driven,
the controller switches between the first image size area and the
second image size area of the image pickup device in accordance
with a state selected by the mode switching member.
[0056] According to the present invention, an optical apparatus
comprises:
[0057] a taking optical unit including a movable optical component
for varying a focal length;
[0058] a light amount adjusting unit disposed in an optical path of
the taking optical unit, the light amount adjusting unit varying an
aperture to adjust an amount of light and changing and F-number by
varying the aperture;
[0059] an image pickup device for picking up an optical image
formed by the taking optical unit, the image pickup device having a
first image size area for performing image pickup and a second
image size area for performing image pickup including the first
image size area and larger than the first image size area;
[0060] a mode switching member for selecting a dynamic image taking
mode and a static image taking mode; and
[0061] a light amount controller for controlling the variation in
the aperture of the light amount adjusting unit, the light amount
controller setting different values of the F-number of the light
amount adjusting unit at the same focal length of the taking
optical unit in accordance with a state selected by the mode
switching member; and
[0062] an image pickup controller for controlling image pickup of
the image pickup device, the image pickup controller switching
between the first images size area and the second image size area
of the image pickup device in accordance with a state selected by
the mode switching member when the movable optical component is
driven.
[0063] Other configurations and objects will be obvious in the
description of preferred embodiments, later described.
BRIEF DESCRIPTION OF THE DRAWINGS
[0064] FIG. 1 is a schematic diagram illustrating the configuration
of a camera according to a first embodiment of the present
invention;
[0065] FIG. 2 is a cross section view of optics for illustrating a
numerical embodiment for photographic lenses used in the
camera;
[0066] FIG. 3 show aberration curves in the numerical embodiment
for the photographic lenses, in which the upper diagrams illustrate
aberration of the entire lens system in taking dynamic images at
focal length fw and the lower diagrams illustrate aberration in
taking static images at focal length fsw;
[0067] FIG. 4 show aberration curves in the numerical embodiment
for the photographic lenses, in which the upper diagrams illustrate
aberration of the entire lens system in taking dynamic images at
focal length fm and the lower diagrams illustrate aberration in
taking static images at focal length ft;
[0068] FIG. 5 illustrates the relationship between a focal length
and an F-number for a maximum aperture in the camera;
[0069] FIG. 6 is an explanation diagram showing image sizes of the
photographic lenses in the camera;
[0070] FIG. 7 illustrates a frequency characteristic showing
performance of an ideal lens with no aberration represented by
F-numbers;
[0071] FIG. 8 is a flow chart illustrating the operation sequence
in the camera;
[0072] FIG. 9 is a schematic diagram illustrating the configuration
of a camera according to a second embodiment of the present
invention;
[0073] FIG. 10 is a flow chart illustrating the operation of the
camera of the second embodiment; and
[0074] FIG. 11 illustrates spherical aberration of photographic
lenses in the camera of the second embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0075] FIG. 1 illustrates the configuration of a camera according
to a first embodiment of the present invention. FIG. 2 is a cross
section for illustrating a numerical embodiment for photographic
lenses used in the camera, and FIGS. 3 and 4 are aberration curves
thereof. FIG. 5 illustrates the relationship between a focal length
of the photographic lenses and an F-number for a maximum aperture
set for each focal length in the camera. FIG. 6 shows image sizes
of the photographic lenses in the camera. FIG. 7 illustrates a
frequency characteristic showing performance of an ideal lens with
no aberration represented by F-numbers. FIG. 8 shows a flow chart
illustrating the operation sequence in the camera.
[0076] In FIG. 1, reference numeral 1 shows a zoom photographic
lens system (photographic optical system). Reference numeral 2
shows a vibration correcting lens forming part of lenses
constituting the photographic lens system 1 for performing
vibration isolation (so-called camera shake correction) by a
displacement in a direction orthogonal to an optical axis.
[0077] Reference numeral 3 shows an image pickup device for which a
solid-state image sensor is used such as a CCD or a CMOS with a
cell pitch (a pitch of arranged pixels) of approximately 3
micron.
[0078] Reference numeral 4 shows a mode selection switch for
switching between dynamic image taking (a dynamic image mode) and
static image taking (a static image mode). In the camera of the
embodiment, the photographic lens system 1 and the image pickup
device 3 are used in common to take both dynamic images and static
images. For example, dynamic image information is recorded in a
recording medium such as a video tape or a DVD, not shown, while
static image information is recorded in a recording medium such as
a sticklike or compact memory device or a DVD. In addition, the
dynamic image information and the static image information are
recorded on the same recording medium, for example on the same
memory device.
[0079] Reference numeral 9 shows a camera control circuit
responsible for control of the overall operation of this camera.
Reference numeral 5 shows a zoom control circuit for zooming
control of the photographic lens system 1 in response to a command
signal from the camera control circuit 9.
[0080] Reference numeral 6 shows a vibration isolation control
circuit for shifting control of the vibration correcting lens 2 in
response to a command signal from the camera control circuit 9.
Reference numeral 7 shows a stop control circuit for drive control
of a stop SP in response to a command signal from the camera
control circuit 9. In the embodiment, a predetermined F-number can
be obtained by controlling the stop SP.
[0081] Reference numeral 8 shows an image pickup area control
circuit for controlling switch of image pickup areas (image sizes)
on the image pickup device 3 in response to a command signal from
the camera control circuit 9.
[0082] A shutter mechanism, the illustration of which is omitted,
is provided on an optical axis ahead of the image pickup device 3
or on an optical axis within the photographic lens system 1. The
shutter mechanism maintains an opened state in the dynamic image
taking mode to exert no influence on an amount of light for the
photographic lens system 1, while it is driven in the static image
taking mode to move from the opened state to a totally closed state
at a predetermined timing under control of the camera control
circuit 9 such that a predetermined amount of light is obtained as
a stored amount of light in light-receiving pixels of the image
pickup device 3. The image pickup device 3 is controlled by the
image pickup area control circuit 8 to vary a time period for
storing light such that the stored amount of light in the
light-receiving pixels is equal to the predetermined amount of
light. It should be noted that the function of varying the time
period for storing light in the light-receiving pixels of the image
pickup device 3 is referred to as "an electronic shutter."
[0083] Next, the operation of the camera (mainly of the camera
control circuit 9) will hereinafter be described in accordance with
the flow chart of FIG. 8. First, power is turned on by throwing a
main switch, not shown, to start the flow. Then, at step
(abbreviated as "S" in FIG. 8) 1, the state of the mode selection
switch 4 is detected to determine whether the camera is in the
dynamic image mode or the static image mode.
[0084] When the camera is in the dynamic image mode, the flow
proceeds to step 2 at which an image size is set through the image
pickup area control circuit 8 such that an image is obtained from a
range of a dynamic image pickup area 3d (for example, .phi.3.9 or
2.34 mm.times.3.12 mm) of the image pickup device 3 shown in FIG.
6.
[0085] Subsequently, at step 3, the focal length of the
photographic lens system 1 in the dynamic image mode is set to have
a variable range of fw to ft, i.e. a full range from the wide end
to the tele end.
[0086] Next, at step 4, an F-number for a maximum aperture with
respect to a focal length in the dynamic image mode is set as
controlled on an aperture curve d for dynamic images shown in FIG.
5. In the embodiment, the F-number for the maximum aperture in the
dynamic image mode varies in a range of 1.65 to 2.2 in accordance
with a focal length.
[0087] At step 5, an F-number for a minimum aperture in the dynamic
image mode is set to a minimum aperture value for dynamic images
(for example, F11).
[0088] Then, at step 6, the stop SP in the dynamic image mode is
controlled between the F-number for the maximum aperture set at
step 4 and the F-number for the minimum aperture set at step 5.
[0089] At step 7, optical vibration isolation control is started by
shifting the vibration correcting lens 2 in a direction orthogonal
to an optical axis based on information from a vibration detecting
means (for example, formed of an acceleration or velocity sensor
and a circuit for integrating the output from the sensor) provided
for the photographic lens or the camera body.
[0090] Next, at step 8, it is determined whether camera shake can
be corrected only by shifting the vibration correcting lens 2 as
described above (whether the correction of the vibration is
insufficient) in the dynamic image mode, and if not, so-called
electronic vibration isolation control is performed by shifting the
aforementioned dynamic image pickup area to another one and taking
the other area from within a wider area (for example, 3.06
mm.times.4.08 mm at the maximum) on the image pickup device 3.
[0091] On the other hand, when the camera is determined as being in
the static image taking mode at step 1, the flow proceeds to step
10 at which a larger image size (with a higher number of pixels)
than that in taking dynamic images is set such that an image is
obtained from a static image pickup area (for example, .phi.5.1 or
3.06 mm.times.4.08 mm) on the image pickup device 3.
[0092] Next, at step 11, the focal length in the static image mode
is limit to a variable range of fsw to ft, i.e. of the wide end fsw
in static images at a position shifted somewhat to the tele end
from the wide end in taking dynamic images, to the tele end ft.
With this limit, in taking static images, zooming cannot be made in
a range of fw to fsw closer to the wide end in which zooming can be
made in taking dynamic images.
[0093] It is thus possible to eliminate an influence upon static
images, exerted by distortion of the photographic lens system 1 or
residual aberration such as comatic aberration or chromatic
difference of magnification, which is significant in a range closer
to the wide end. Therefore, the quality of static images can be
improved without increasing the size of the photographic lens
system 1 and with necessary variable powers (fsw to ft) ensured to
a certain degree.
[0094] At step 12, an F-number for a maximum aperture with respect
to a focal length in the static image mode is set as controlled on
an aperture curve s for static images shown in FIG. 5. In the
embodiment, the F-number for the maximum aperture in the static
image mode varies in a range of 1.83 to 2.88 in accordance with a
focal length.
[0095] In other words, in the embodiment, the F-number for the
maximum aperture is set to be larger in the static image taking
than the dynamic image taking for the same focal length in the
focal length range of fsw to ft, that is, the open F-number is set
to pass less light in the static image taking than the dynamic
image taking for the same focal length. In the embodiment, the open
F-number is set to pass less light in the static image taking than
the dynamic image taking particularly in a range closer to the tele
end.
[0096] Then, at step 13, an F-number for a minimum aperture in the
static image mode is set to a minimum aperture value for static
images (for example, F8) which allows more light than in the
dynamic image mode. In other words, setting is made such that the
aperture cannot be stopped down in the static image mode to an
F-number (for example, F11) which can be set in the dynamic image
mode.
[0097] In a range of F8 to F11, degradation in performance due to
physical optics factors in a diffraction phenomenon is greater than
improvement in optical resolution due to geometrical optics
aberration reduction factors near on an axis resulting from a
larger F-number. For this reason, the F-number for the minimum
aperture in taking static images in this range is set to be smaller
than the F-number for the minimum aperture in taking dynamic
images.
[0098] Thus, in the embodiment, at step 14, the stop SP in the
static image mode is controlled between the F-number for the
maximum aperture set at step 12 and the F-number for the minimum
aperture set at step 13.
[0099] At the aforementioned step 14, the aperture control is
performed between the maximum aperture and the minimum aperture in
the static image mode, and at this time, to compensate for the
light amount adjustment with the aperture, low object brightness is
preferably compensated for an insufficient amount of light by a low
shutter speed with the shutter mechanism (not shown) or the
electronic shutter of the image pickup device 3 or an electronic
flash (not shown).
[0100] With the minimum aperture F-number in taking static images
set to be smaller (to pass more light) than the minimum aperture
F-number in taking dynamic images, it is preferable to use a high
electronic shutter speed with the image pickup device 3 or a high
shutter speed with the shutter mechanism (not shown) in the
photographic lens system 1 to avoid an excessive amount of light
for high object brightness.
[0101] At step 15, optical vibration isolation control, similar to
the aforementioned one at step 7, is started.
[0102] As described above, according to the embodiment, since the
open F-number is set to pass less light in the static image taking
than the dynamic image taking for the same focal length of the
photographic lens system 1, bright dynamic images can be taken
while it is possible to suppress degradation in optical performance
due to spherical aberration, chromatic aberration, assembly
decentering errors or the like of the photographic optical system 1
in taking static images. Therefore, aberration and the like can be
favorably corrected in the compact photographic lens system 1 to
realize a camera capable of taking bright dynamic images and
high-quality static images with a lighter load on dynamic image
processing.
[0103] While the embodiment has been described for the maximum
aperture F-number controlled to provide completely different
characteristics as shown in the curve d and the curve s in FIG. 5
(no intersection of the two lines) between the dynamic image taking
and the static image taking, it is essential that the maximum
aperture F-number in taking dynamic images for focal length ft is
set to be smaller than the maximum aperture F-number in taking
static images to obtain favorable quality of static images. Thus,
it may be possible in taking dynamic images to use a curve d' on
which the maximum aperture F-number in taking dynamic images for
focal length fsw matches the maximum aperture F-number in taking
static images.
[0104] In the embodiment, the image size on the image pickup device
3 in taking static images is larger than the image size in taking
dynamic images to use a higher number of pixels in the static image
taking than the dynamic image taking, thereby achieving high image
quality of static images. In this case, the aforementioned control
of the open F-number to pass less light in taking static images
allows favorable correction of peripheral aberration in the static
images without increasing the size of the photographic lens system
1, which enables high-quality static images.
[0105] In addition, in the embodiment, the minimum aperture
F-number (F=8) in taking static images is set to be smaller than
the minimum aperture F-number (F=11) in taking dynamic images in
the aperture range from approximately F=8 to 11 of the F-number
variable range of the stop SP, that is, in the range in which
degradation in performance due to physical optics factors in a
diffraction phenomenon is greater than improvement in optical
resolution due to geometrical optics aberration reduction factors
near on an axis resulting from a higher F-number. Such setting can
provide higher image quality in the static image taking than the
dynamic image taking.
[0106] The above will specifically be described with reference to
FIG. 7. FIG. 7 shows a frequency characteristic for contrast
represented by F-numbers of an ideal lens with no aberration, for
illustrating how the optical performance of the photographic lens
system 1 is changed with the F-numbers.
[0107] In FIG. 7, when the F-number is increased to F8, the
contrast is reduced to approximately 50% at 80 line pairs
corresponding to half in the Nyquist line pair spatial frequency in
a three-micron pitch CCD. Since the contrast is further reduced
when the actual photographic lens system 1 with inherent aberration
is used, the F-number is controlled not to be larger than F8 in
taking static images in the embodiment to obtain high-quality
static images.
[0108] Here, the following condition is desirably satisfied:
0.2<Fsmin X.lamda./P<4.4 (1) where P represents the pitch of
the repeatedly arranged light receiving pixels of the image pickup
device 3, .lamda. represents a reference wavelength for image
taking of light rays sensed by the image pickup device 3, and Fsmin
represents the F-number for the minimum aperture in the stop (light
amount adjusting unit) in the static image taking mode.
[0109] Substituting Fsmin=8, .lamda.=0.588, and P=3 into the
central term of the conditional expression (1) yields 1.57 (Fsmin X
.lamda./P=1.57) which satisfies the relationship of the conditional
expression (1), where .lamda.=0.588 represents a wavelength of 588
nm of d rays serving as a reference wavelength for taking images,
and P=3 represents a pitch of 3 .mu.m of the arranged pixels in the
CCD serving as the image pickup device 3.
[0110] In the aforementioned expression (1), a lower limit value is
preferably set to 0.4, and more preferably to 0.8, for obtaining a
wider range in which a light amount can be adjusted. In addition,
an upper limit value set to 3.3 or 2.2 is suitable for suppressing
degraded performance due to a diffraction phenomenon.
[0111] In the embodiment, the image size in taking dynamic images
when vibration isolation is performed is set to be smaller than the
image size in taking static images when vibration isolation is
similarly performed, and thus dynamic images are taken in an inner
image pickup area excluding the peripheral area where an amount of
light tends to be unbalanced in association with the vibration
isolation, so that the unbalanced light amount in the periphery
associated with the vibration isolation can become less prominent
in taking dynamic images. Thus, sufficient vibration isolation can
be performed in taking dynamic images without increasing the size
of the photographic lens system 1.
[0112] Since the taking of a static image which captures moments
originally has a wider allowable range of an unbalanced light
amount in the periphery, unbalance of a light amount in the
periphery produced in the vibration isolation is not prominent even
with the larger image size.
[0113] In addition, since the maximum aperture F-number in taking
static images is set to be larger than the maximum aperture
F-number in taking dynamic images for the same focal length of the
photographic lens system 1, it is possible to improve an unbalanced
light amount in the periphery during the vibration isolation when
images are taken at the maximum aperture in taking static
images.
[0114] While the aforementioned embodiment has been described for
the maximum aperture F-number in taking static images set to be
larger than the maximum aperture F-number in taking dynamic images
for the same focal length in the partial range from fsw to ft of
the full variable range from fw to ft of the focal length, the
maximum aperture F-number in taking static images may be set to be
larger than the maximum aperture F-number in taking dynamic images
for the same focal length in the full variable range from fw to ft
of the focal length.
[0115] Also, while the aforementioned embodiment has been described
for the use of the photographic lens system of a
variable-focal-length lens type, the present invention is
applicable to the use of a photographic lens system of a single
focal length lens (a fixed-focal-length lens).
Numerical Embodiment
[0116] Next, Table 1 shows a numerical embodiment for the
photographic optical system used in the optical apparatus of the
present invention.
[0117] As shown in FIG. 2, the photographic optical system is a
zoom lens of a four-group rear focusing type, comprising fixed
first-group lenses L1, second-group lenses L2 serving as a
varietor, an stop SP, third-group lenses (vibration correcting
lens) L3, a flare stopper FS, fourth-group lenses L4 serving as a
focus lens and compensator, and a glass block G such as a faceplate
or a filter, all of which are arranged in this order from a
position closer to an object.
[0118] A solid line 4a shown under the fourth-group lenses L4 in
FIG. 2 indicates the movement of the fourth-group lenses L4 for
correcting image plane variations associated with varied power from
the wide end to the tele end when an object at infinity is brought
into focus. A dotted line 4b indicates the movement of the
fourth-group lenses L4 for correcting image plane variations
associated with varied power from the wide end to the tele end when
an object at a short distance is brought into focus.
[0119] FIG. 2 illustrates cross sections of optics, from the top,
at focal length fw (the wide end in taking dynamic images) of the
photographic optical system, fsw (the wide end in taking static
images), and fm (middle), and ft (the tele end). FIGS. 3 and 4 are
aberration curves for each of the above focal lengths.
[0120] In Table 1, ri represents a radius of curvature of i-th one
of surfaces arranged in order from the object, di represents a
distance (a value of equivalent air) between i-th surface and
(I+1)th surface in order from the object, Ni and vi (written as "v"
in Table 1) represent a refractive index and an Abbe number of
glass of i-th optical member in order from the object,
respectively.
[0121] An aspheric shape in the 14th row in Table 1 is represented
by the following equation: X = H 2 / R 1 + 1 - ( 1 + K ) .times. (
H / R ) 2 + AH 2 + BH 4 + CH 6 + DH 8 + EH 10 ##EQU1##
[0122] where an X axis is taken in an optical axis direction, an H
axis is taken in a direction orthogonal to the optical axis, light
travels in a positive direction, R represents a paraxial radius of
curvature, and K, A, B, C, D, and E each represent aspheric
coefficients. In addition, the notation of "e-z" means "10.sup.-z."
TABLE-US-00001 f = 4.32.about.42.02 FNo = 1: 1.65.about. 2.omega. =
48.6.degree..about. r1 = 45.054 d1 = 1.40 n1 = 1.84666 v1 = 23.9 r2
= 25.429 d2 = 6.96 n2 = 1.48749 v2 = 70.2 r3 = -171.864 d3 = 0.20
r4 = 21.420 d4 = 3.55 n3 = 1.77250 v3 = 49.6 r5 = 56.119 d5 =
variable r6 = 62.351 d6 = 0.60 n4 = 1.84666 v4 = 23.9 r7 = 5.298 d7
= 2.81 r8 = -14.229 d8 = 0.50 n5 = 1.78590 v5 = 44.2 r9 = 137.803
d9 = 0.20 r10 = 11.940 d10 = 2.74 n6 = 1.84666 v6 = 23.9 r11 =
-11.940 d11 = 0.50 n7 = 1.60311 v7 = 60.6 r12 = 19.515 d12 =
variable r13 = .infin. (stop) d13 = 3.30 r14 = 12.798 (aspheric
surface) d14 = 1.89 n8 = 1.80610 v8 = 40.7 r15 = 99.912 d15 = 3.83
r16 = 22.767 d16 = 0.50 n9 = 1.84666 v9 = 23.9 r17 = 7.926 d17 =
2.70 n10 = 1.48749 v10 = 70.2 r18 = -33.906 d18 = 1.01 r19 =
.infin. d19 = variable r20 = 13.355 d20 = 2.66 n11 = 1.78590 v11 =
44.2 r21 = -13.355 d21 = 0.50 n12 = 1.84666 v12 = 23.9 r22 =
175.611 d22 = variable r23 = .infin. d23 = 3.60 n13 = 1.51633 v13 =
64.1 r24 = .infin. fw fsw fm ft focal length variable distance 4.32
5.33 17.78 42.02 d5 0.84 3.67 15.02 19.75 d12 20.60 17.76 6.42 1.69
d19 3.44 2.91 1.12 4.12 d22 3.49 4.02 5.81 2.81 aspheric
coefficient K A B C D E 14.sup.th -7.0131e-01 0.0000e+00
-1.8642e-05 -2.0047e-07 1.5637e-08 -1.9706e-10 surface
[0123] In the numerical embodiment, the rear focusing type as
mentioned above is employed to prevent degraded performance due to
decentering errors in the first-group and to effectively prevent an
increase in effective aperture of the first-group lenses as
compared with focusing by moving a first-group forward in a
so-called four-group zoom lens.
[0124] The stop SP is disposed immediately before the third-group
or in the third-group to reduce variations in aberration from the
moving lens group, and the distance between the lens groups before
the stop SP is reduced to readily achieve a reduction in diameter
of the first-group lenses.
Second Embodiment
[0125] FIG. 9 illustrates the configuration of a camera according
to a second embodiment of the present invention. In FIG. 9,
reference numeral 21 shows a zoom photographic lens system
(photographic optical system) which includes a fixed first-group
lens 21a, a second-group lens 21b to be driven for varying power in
an optical axis direction, a fixed third-group lens 21c, and a
fourth-group lens 21d to be driven for focusing. The photographic
lens system 21 has a four-group configuration having convex,
concave, convex, and convex power in this order from a subject.
[0126] Reference numeral 28 shows a stop controlled by an aperture
value control actuation circuit 25 such that the detection result
of an aperture value by an aperture value detection circuit 27 is a
target value. Reference numeral 22 shows an image pickup device
such as a CCD, and video signals from the image pickup device 22
are input to a camera signal processing circuit 23 for performing
various types of signal processing.
[0127] Reference numeral 24 shows a zoom motor drive circuit for
controlling the driving of a zoom motor, not shown, for moving the
second-group lens 21b according to the zooming operation of a
photographer. Reference numeral 26 shows a focus motor drive
circuit for controlling the driving of a focus motor, not shown,
for moving the fourth-group lens 21d according to autofocus signals
produced with signals from the image pickup device 22.
[0128] Reference numeral 30 shows a camera control circuit
responsible for controlling the operation of each of the
aforementioned circuits. Reference numeral 31 shows a mode
selection switch for selecting a dynamic image taking mode or a
static image taking mode through the operation of a
photographer.
[0129] Next, the operation for taking images in the camera
configured as described above will be described with reference to a
flow chart shown in FIG. 10.
[0130] After power is turned on first in the camera (step
(abbreviated as "S" in FIG. 10) 21), the camera control circuit 30
detects the state of the mode selection switch 31 to determine
whether the dynamic image taking mode is set (step 22). The flow
proceeds to step 23 when the dynamic image taking mode is set, or
to step 25 when the dynamic image taking mode is not set.
[0131] At step 23, it is determined whether a dynamic image taking
switch (not shown) for starting dynamic image taking is turned on.
If not, the flow returns to step 22. If the switch is turned on,
the flow proceeds to step 24 to start dynamic image taking.
[0132] An F-number in taking dynamic images is controlled in
accordance with the focal length of the photographic lens system 21
in a range from an open value of F1.4 to a minimum aperture value
of F16.
[0133] On the other hand, at step 25, the state of the mode
selection switch 31 is detected to determine whether the static
image taking mode is set. The flow proceeds to a reproduction mode
when the static image taking mode is not set, or to step 26 when
the static image taking mode is set.
[0134] At step 26, it is determined whether a static image taking
switch (not shown) for starting static image taking is turned on.
If not, the flow returns to step 22. If the switch is turned on,
the flow proceeds to step 27 to start static image taking.
[0135] An F-number in taking static images is controlled in
accordance with the focal length of the photographic lens system 21
in a range from an open value of F2.8 to a minimum aperture value
of F8.
[0136] The open F-number in taking static images is controlled to
be larger than the open F-number in taking dynamic images for the
same focal length. The minimum aperture F-number in taking static
images is controlled to be smaller than the minimum aperture
F-number in taking dynamic images for the same focal length.
[0137] The open F-number in taking static images is set to be
larger (for less light) than the open F-number in taking dynamic
images in this manner because the dynamic image taking only
requires a normal level of image quality and places more importance
on brightness of images than image forming performance to obtain
high image quality, while the static image taking places importance
on suppressing degradation in image forming performance due to
spherical aberration, chromatic aberration or the like in the
photographic lens system 21 to obtain higher image quality.
[0138] The minimum aperture F-number in taking static images is set
to be smaller (for more light) than the minimum aperture F-number
in taking dynamic images because the static image taking more
strongly requires prevention of degradation in image forming
performance due to small aperture diffraction than the dynamic
image taking.
[0139] The number of pixels for image pickup in the image pickup
device 22 may be higher (a larger image size) in the static image
taking than the dynamic image taking to allow static images to be
taken with a higher resolution than the dynamic image taking.
[0140] FIG. 11 is an aberration curve for explaining the spherical
aberration produced in the photographic lens system 21 in the
embodiment.
[0141] While a paraxial image plane position and an optimal image
plane position are spaced at F1.4, an optimal image plane position
b is closer to the paraxial image plane position at F2.8. Thus, the
open F-number in taking static images set to F2.8 can reduce an
influence of spherical aberration upon taken images to obtain
high-quality static images.
[0142] It should be noted that the values of the open F-number and
the minimum aperture F-number in taking static images and dynamic
images used in the embodiment are only illustrative, and other
F-numbers may be used.
[0143] As described above, in the aforementioned embodiment, since
the maximum aperture F-number in taking static images is larger
than that in taking dynamic images for the same focal length,
bright dynamic images can be taken, and at the same time, it is
possible to suppress degraded optical performance due to spherical
aberration, chromatic aberration, assembly decentering errors or
the like of the photographic optical system in taking static
images. Thus, a compact photographic optical system can be used to
realize a camera capable of taking bright dynamic images and
high-quality static images with a lighter load on dynamic image
processing.
[0144] When the image size in taking static images is set to be
larger than the image size in taking dynamic images, the number of
pixels in the static image taking can be higher than the dynamic
image taking to improve the quality of static images. In this case,
the application of the aforementioned invention enables favorable
correction of peripheral aberration in static images without
increasing the size of the photographic optical system, thereby
making it possible to realize a compact camera capable of taking
high-quality static images.
[0145] In the aforementioned embodiment, the minimum aperture
F-number in taking static images and the minimum aperture F-number
in taking dynamic images are set such that the former is set to be
smaller than the latter in the partial range of the full F-number
variable range in which degradation in performance due to physical
optics factors in a diffraction phenomenon is greater than
improvement in optical resolution due to geometrical optics
aberration reduction factors near on an axis resulting from a
higher F-number. Thus, more excellent image quality in taking
static images than the image quality in taking dynamic images can
be obtained.
[0146] In addition, in the aforementioned embodiment, since the
minimum aperture F-number in taking static images is set to be
smaller than the minimum aperture F-number in taking dynamic images
and the conditional expression (1) is satisfied, it is possible to
prevent an excessive amount of light even with a high shutter speed
(when the F-number is less than the lower limit) resulting from too
low an F-number for a pitch of light receiving pixels, or to
prevent reduced image quality (when the F-number is above the upper
limit) in taking static images resulting from significantly
deteriorated performance due to small aperture diffraction.
[0147] Furthermore, in the aforementioned embodiment, when the
maximum aperture F-number in taking static images is set to be
larger than the maximum aperture F-number in taking dynamic images
for the same focal length of the photographic optical system, a
compact photographic optical system can be used to realize a camera
capable of taking bright dynamic images and high-quality static
images with a lighter load on dynamic image processing as described
above.
* * * * *