JPH07253529A - Automatic focusing camera with macro lens - Google Patents

Abstract

PURPOSE:To eliminate an unrequired lens scan and to perform smooth focusing operation in automatic focusing adjustment with a macro lens by driving a photographing lens to a prescribed position on a short distance side when a subject is discriminated to exist on the short distance side shorter than a prescribed distance. CONSTITUTION:First of all, a distance is decided by first, second light flooding/ light receiving parts 13, 15, and a lens side micro computer (LCPU) 17 compares the quantity of a received light with that of a prescribed reference level, and discriminates whether or not the subject exists on the short distance side shorter than a prescribed distance, or whether or not the subject exists within a macrophotographing area, and transmits the discriminated result to a body side micro computer (BCPU) 21. Then, when the subject is discriminated to exist at no great distance, the photographing lens 1 is pre-driven, that is, driven to a position equivalent to the distance value of the prescribed short distance in advance. When no macrophotographing lens is used, no pre-drive is performed. Then, the LCPU 17 performs AF detection of a passive system by a ranging part 13 in a camera main body 2, and thus, when the deviation is found, the CPU 17 decides focusing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focus adjusting device for a camera to which a macro photographing lens such as a macro photographing interchangeable lens or a macro photographing zoom lens can be attached or integrated.

[0002]

2. Description of the Related Art Conventionally, when shooting with a shooting lens capable of macro shooting as described above, the amount of extension of the shooting lens is extremely large during macro shooting compared to shooting in a normal shooting range, and the subject is not visible during autofocus shooting. Depending on the positional relationship between the lens and the taking lens, focus detection may not be possible once. In such a state, a method is used in which the photographing lens is scanned until the position where the focus detection light flux is guided to the sensor, that is, the state where the subject information is obtained.

[0003]

In the above-mentioned conventional technique, the time required for lens scanning becomes long due to the amount of extension and the problem of missing a photo opportunity occurs. This becomes even larger if the condition of the subject is bad. In order to solve the above-mentioned inconvenience, it is known to provide a focus limit switch for limiting the drive amount to either the macro shooting area or the normal shooting area. However, with such a configuration, when the user wants to switch from the normal shooting area to the macro shooting area during shooting, or vice versa, the user has to release the focus limit switch each time, which causes a trouble. .

The present invention has been made in view of the above problems, and in autofocus photographing using a lens capable of macro photographing, the time until focusing is shortened and a shutter chance is missed. It is an object of the present invention to provide an automatic focus adjustment device for a camera that prevents unnecessary lens scan driving and enables smooth shooting.

[0005]

In an automatic focus adjusting device for a camera having a lens capable of macro photography, distance measuring means, light projecting means provided on the lens for projecting light onto a subject, and provided on the lens. The light receiving means for receiving the reflected light from the subject of the projected light; the determining means for determining whether or not the subject is closer than a predetermined distance based on the output of the light receiving means; and the determining means, When it is determined that the object is closer to the predetermined distance than the predetermined distance, the photographing lens is driven to a predetermined position on the short distance side, and then the photographing lens is driven to the in-focus position based on the output of the distance measuring means. And have.

[0006]

In performing the automatic focusing operation, when the subject is closer to the predetermined distance than the predetermined distance, the lens is driven to the predetermined short distance position prior to the automatic focusing operation, and then the focusing operation is performed. To perform.

[0007]

FIG. 1 is a schematic view showing an embodiment of a camera to which the present invention is applied. In the figure, a photographing lens 1 is a macro photographing lens such as a macro photographing interchangeable lens or a macro photographing zoom lens, and is detachably attached to a camera body 2. The light flux from the subject that has passed through the photographing lens 1 is reflected downward by a main mirror 3a and a sub mirror-3b that are rotatably provided in the camera body 2 as is known, and is guided to the distance measuring unit 4. The distance measuring unit 4 outputs data related to distance measurement as is known, and drives the taking lens 1 to a focal point through an appropriate control circuit.

FIG. 2 is a block diagram showing the circuit configuration of the above embodiment. In the figure, reference numeral 1 denotes a lens capable of macro photography, and 2 denotes a camera body, each of which has a lens side microcomputer (hereinafter abbreviated as LCPU) 17 and a body side microcomputer (hereinafter abbreviated as BCPU) 21. The LCPU 17 and the BCPU 21 are connected via a communication line terminal group 19 provided on the lens mount section. Further, the LCPU 17 is provided with an information storage section indicating a lens type that is a lens capable of macro photography in its internal storage circuit section. The lens barrel front frame 1a of the lens 1 has an infrared projection LE as shown in FIGS.
The light projecting means 13a, 15a composed of D etc. and the light receiving means 13b, 15b composed of SPD etc. are paired as the first light projecting / light receiving section 13 and the second light projecting / light receiving section 15, respectively.
They are arranged symmetrically above and below the optical axis of the lens. The light projecting means 13a and 15a project infrared light toward the subject, and the light receiving means 13b and 15b receive reflected light of the infrared light from the subject. Further, the first light emitting / receiving unit 13 and the second light receiving / receiving unit 15 function to discriminate the zone of the object distance, as will be apparent from the contents described later. Here, the reason why the first light emitting / receiving unit 13 and the second light receiving / receiving unit 15 are arranged vertically is that the distance between the subject and the camera in the macro region, that is, the so-called working distance is short, and the non-TTL Problems caused by parallax in the light emitting and receiving system,
That is, this is a configuration for reducing the problem caused by the shift of the visual field from the distance measuring unit 4 in the camera body, and the effect can be reduced by providing a plurality of light emitting / receiving units as shown in FIG. .

Further, the light projecting means 13 is provided in the lens 1.
a, 15a for projecting the light intermittently a predetermined number of times, and for integrating the received light amount data signal from the light receiving means 13b, 15b which receives the reflected light from the subject of the intermittent light emission. Light receiving control means is provided. The light projecting control means and the light receiving control means respectively match the pair of light projecting means 13a, 15a and the light receiving means 13b, 15b, and the light projecting control circuits 14a, 16a and the light receiving control circuit 14 respectively.
One pair is provided as b and 16b. These control means are controlled by the LCPU 17. Further, in the lens 1, a drive control means 12 for driving the lens and an output control means 18 for outputting an encoder output indicating a lens drive position and lens information are arranged.

On the other hand, the BCPU 21 is provided on the camera body side.
And the distance measuring unit 4 is provided. The distance measuring unit 4 has a known structure including a distance measuring element 4a composed of a pair of line sensors such as CCDs. The lens drive control means 12 in the lens 1 includes the light receiving control circuits 14b and 16b, the information output control means 18, the distance measuring unit 4, the LCPU 17, and the BCP.
The lens is driven based on the information processing result with U21 and the like. Here, the light projecting means 13a,
15a is generally adapted to use light in a wavelength range outside the luminosity such as infrared light, and the light receiving means 13b, 1
5b is also adapted to be sensitive mainly to the infrared region. In this embodiment, a light source having a peak wavelength of 960 nm is used. For this reason, the visible light cut filter 30 is provided in front of the light projecting means 13a, 15a and the light receiving means 13b, 15b. In the case of such a configuration, due to the presence of the visible light cut filter 30, the reflected light from the subject is reflected by this filter 30, and this light reaches the film surface through the taking lens during photographing. There is a fear. As a countermeasure, in this embodiment, as shown in FIG.
As shown in FIG. 5, movable light shielding members 1b and 1c are arranged between a position where the front surface of the filter 30 is covered and a position where the filter 30 is opened. The light blocking members 1b and 1c are slidably held around the optical axis on the lens barrel front surface 1a, and the driven arms 1d and 1g are respectively extended from the rear side in the optical axis direction. There is. The driven arms 1d and 1g extend to the rear side of the lens frame front surface portion 1a through elongated holes (not shown) provided in an arc shape around the optical axis, and drive arms 1e,
It comes into contact with 1f in a one-sided contact state. The drive arm 1e,
1f is formed integrally with the diaphragm drive ring 1i. The diaphragm drive ring 1i is rotatably held in the lens 1 and is rotationally driven by a stepping motor M. Further, springs 1h and 1j for attracting the driving arms 1e and 1f and the driven arms 1d and 1g are respectively stretched between the driving arms 1e and 1f.

Next, the operation of the above embodiment will be described. First, the distance determination by the first and second light emitting / receiving units 13 and 15, that is, the zone determination as to whether or not the subject is at a short distance will be described. As shown in FIG. 6, when the subject O is close to the camera 2, the distance L from the tip of the taking lens 1 to the subject O is small, and the light emitted from the tip of the taking lens 1 is
The amount of light received by the light receiving means 13b and 15b is large. On the other hand, when the subject O is far away, the reflected light from the subject is small, and the amount of light received by the light receiving means 13b and 15b is small. LC
The PU 17 compares the magnitude relationship of the received light amount with a predetermined reference level to determine whether the subject is at a predetermined distance, for example, 1 m, closer, or within the macro shooting area, This is transmitted to the BCPU 29. The LCPU 17 in the lens 1 controls the first and second light emitting / receiving units 13 and 15. FIG. 7 shows the time chart. When the subject presence / absence determination command is output from the BCPU 21, the LCPU 17 sends a light emission permission signal TH1 to the light emission control circuits 14a and 16a. This light emission control circuit 14
a and 16a receive the signal TH1 and IRE at a predetermined cycle.
Output D signal. The light projecting means 13a and 15a project light onto the subject in synchronization with Hi of this signal. When the subject is relatively close to the subject, the reflected light from the subject due to the projection becomes large, and therefore the slope of the integrated value INT output of the outputs from the light receiving means 13b and 15b also becomes large. After projecting and receiving light for a predetermined number of times, the LCPU 17 samples and holds the integrated output in synchronization with the sample-hold pulse SH, A / D-converts it, calculates the amount of reflected light, and determines the subject from a predetermined distance. It is determined whether or not it is on the short distance side. When it is determined that the subject is on the short distance side, the distance determination flag (hereinafter abbreviated as NFLG) is set to 1.

FIG. 8 shows a distance measuring operation performed by the BCPU 21. When the power switch is turned on, the BCPU21
Obtains the type information of the photographic lens attached (step 61). When the photographing lens is a macro photographing lens or when the zoom lens is switched to the macro photographing area, the first switch of the release switch is turned on when the shutter button is half pressed, and the LCPU 17 to the BCPU 21 are turned on.
The state of NFLG is sent to. When NFLG = 1, it is determined that the subject is at a short distance, and the lens is pre-driven, that is, pre-driven to a position corresponding to a predetermined short distance side distance value, for example, 0.5 m (step 6).
2-64). Isn't the lens capable of macro photography, or NFL
When G = 0, this pre-driving is not performed. Next, LCPU
As is known, the distance measuring unit 13 in the camera body performs passive AF detection (steps 65 and 66). As a result, when the shift amount is obtained, the focus determination is performed (step 74).

On the other hand, if it is determined in step 66 that the object is out of focus, it is determined that the object is in a short distance when NFLG = 1, so that the photographing lens is set within a short distance range of, for example, 0.1 m to 1 m. Then, the scanning operation of the taking lens is performed (step 69). When NFLG = 0, it is determined that the subject is at a long distance, so the photographing lens is scanned, for example, in the range of 1 m to infinity (68). After this, the distance measuring unit 4
The focus determination is performed again in step (70), and if in focus, step (7)
Go to 5), and if out of focus, the distance measuring operation ends.

When the shutter button is further pressed, 2nd
When the switch is turned on, the lens is driven based on the distance measurement result (step 76), and then the exposure operation (step 7) is performed.
Perform 8). At this time, when the photographing lens is a macro photographing lens, the first and second light emitting / receiving units 13 and 15 are used.
The cover light shielding members 1b and 1c are operated. That is, after the 2nd switch is turned on, the lens is driven, and then the aperture driving ring 1i is rotated by the stepping motor M to drive the driven arms 1d, 1g via the driving arms 1e, 1f and springs 1h1j. The light shielding members 1b and 1c are located in front of the first and second light emitting / receiving units 13 and 15. Here, the initial position of the diaphragm drive ring 1i is on the further open side of the maximum aperture value of the lens, for example, F1.4, and the light blocking member 1b is moved by moving from this initial position to the maximum aperture value position. 1c is designed to shield the front surfaces of the first and second light emitting / receiving sections 13 and 15 from light. After that, the aperture is set to an appropriate value by rotating the stepping motor M according to the brightness of the subject.
The light blocking members 1b and 1c stay at the light blocking position, and the difference in the amount of movement between the two is absorbed by the springs 1h and 1j. After the exposure operation is completed, the stepping motor M rotates in the reverse direction, and after returning the aperture to the open side, the first and second light emitting / receiving sections 13,
The light blocking member is returned to its original position so that the opening 15 is opened again.

In the above embodiment, the first and second light emitting / receiving sections 13 and 15 are arranged above and below the lens barrel from the viewpoint of preventing problems due to the shift of the visual field. Of course, it is also possible to further increase the number such as up, down, left and right. On the contrary, in the case where the problem due to the shift of the visual field does not appear so much, it may be arranged only at any one position, for example, only on the upper side. Here, in the above-mentioned embodiment, since the first and second light emitting / receiving sections 13 and 15 are arranged on the upper and lower sides, depending on the positional relationship between the subject and the camera and the conditions, the short distance from both the light receiving sections may occur. Various combinations are conceivable, such as when the determination is made, when the short distance determination is made only from one of the light receiving portions, and when both the light receiving portions do not make the short distance determination. In the above embodiment, if at least one of the light receiving units makes a short-distance determination, the NFLG is set to 1
However, this may be appropriately changed depending on the type of the combination of the above determinations. Also,
The distance zone of the subject is determined by, for example, determining whether the subject is closer to 1 m or farther from the distance,
It may be determined whether or not the subject is within the macro shooting area, or may be appropriately determined according to the lens type.
Further, the light shielding members 1b and 1c are operated by the ring 1i for driving the diaphragm. However, this may be operated by receiving a force from the movable mirror-3a or the like, or by using another appropriate drive source. Is also good.

FIG. 9 is a block diagram of the second embodiment of the present invention. In the figure, reference numeral 1 denotes a photographing lens, 2 denotes a camera body, the CPU (LCPU) on the lens side in the first embodiment is eliminated, and the CPU (BCPU) 21 on the body side and the distance measuring section 4 and the first and second CPUs. The light emitting / receiving unit, the lens drive control unit 12, the lens information control unit 18, and the like are all controlled, and the same members are denoted by the same reference numerals, and details thereof will be omitted. Further, in this embodiment, the light projecting control circuit and the light receiving control circuit are integrated as 14 and 16. Further, one of the first light emitting / receiving unit 13 and the second light emitting / receiving unit 15 is a wide-angle system and the other is a narrow-angle system. That is, the light projecting control circuit 14 includes the light projecting element 13 having two different characteristics.
Both a and 15a are controlled. Each light projecting element 13a, 1
5a has directivity as shown in FIG. That is,
One of the light projecting elements 13a, for example, the light projecting element arranged on the upper side of the front surface of the lens frame, has a light projecting characteristic having a relatively strong directivity, that is, a light projecting characteristic of a narrow angle system, as shown in FIG. The other light projecting element 15a, for example, the light projecting element arranged on the lower side of the front surface of the lens frame, has a relatively weak directivity, as shown in FIG. have.

In the above embodiment, as shown in FIG. 11, first, the light emission signal TH1 for the light emitting element 13a having a strong directivity is output from the BCPU 21, and then the integrated signal is AD-converted by the A / D conversion signal SH. After that, the light emission signal TH2 to the light projecting element 15a having a weak directivity continues.
Is output from the BCPU 21, and similarly, A /
D-convert. In this embodiment, the light receiving elements 13b and 15b are configured to be controlled simultaneously by the signal SH of one line. As a result of the above-mentioned two times of light projection / reception, when both the first and second projection / reception sections 13 and 15 judge that the subject is not a short distance, it judges that the subject is far, and at least the first projection / reception is performed. When the unit 13 determines that the distance is short, it determines that the subject is near. Further, when only the second light emitting / receiving unit 15 determines that the distance is short, it is determined that the subject exists near but is around the distance measuring field. Here, as is known, the distance measuring unit 4 in the main body is arranged so that the distance measuring field of view is located at the center of the screen and the switching between the spot distance measuring and the wide field distance measuring is possible. The position of the main subject is selected from the result of the short-distance determination, and the distance measurement is performed according to the selected visual field.

Needless to say, this distance measuring field is also effective for multipoint distance measuring having a plurality of distance measuring fields themselves. In this case, a short distance determination unit may be configured by further providing light emitting / receiving units having directivity in three directions in order to perform light emission according to the distance measurement position. Further, the specifications of the light projecting elements may be different from each other not only in the directivity but also in the light emission energy, so that the determination distance may be different.

According to the constitution of each of the above embodiments, the following inventions can be obtained. (Invention 1) In an automatic focus adjustment type camera having a distance measuring means, a photographing lens having a light projecting means and a light receiving means on the front surface and capable of macro photography, and a subject is within a macro area based on the output of the light receiving means. In the case where it is determined that the subject is in the macro photography area based on the output of the determination means, the determination means determines whether or not the light is emitted, and the light shielding means that selectively covers the front surfaces of the light projecting means and the light receiving means. After pre-driving the taking lens to a predetermined distance position in the macro area,
Based on the output of the distance measuring means, this is driven to the in-focus position, and the light shielding means is retracted from the front surfaces of the light projecting means and the light receiving means before and after the exposure operation so that it is positioned on the front surface during the exposure operation. The automatic focusing camera characterized in that (Invention 2) In an autofocus type camera having a distance measuring means, in a lens interchangeable camera in which a macro photography lens and a normal photography lens are selectively mounted on a camera body, the macro photography lens A light emitting means and a light receiving means, an identifying means for identifying whether the macro photographing lens is attached or a normal photographing lens, and the light receiving means when the macro photographing lens is attached. A discriminating means for discriminating whether or not the subject is closer than a predetermined distance based on the output, and a light shielding means movable between a position for covering the front surfaces of the light projecting means and the light receiving means and a position for opening the front surface. When it is determined that the macro photography lens is attached, the determination means is operated, and the determination means determines the presence of the subject in the macro photography area. Further comprises a lens control means for pre-driving the photographing lens to a predetermined distance within the macro area, and then main-driving the photographing lens to the in-focus position based on the output of the distance measuring means. Is retracted from the front surfaces of the light projecting means and the light receiving means, and is positioned on the front surface during the exposure operation. (Invention 3) In Invention 2, the light projecting means is provided on the front end surface of the lens frame. (Invention 4) In the above Invention 2, the light-shielding means is composed of a light-shielding plate member movable around the optical axis of the lens. (Invention 5) In an autofocusing type camera to which an interchangeable lens for macro photography can be attached, a projecting means provided on the interchangeable lens for macro photography and projecting light for determining a subject zone, and the macro photography. Based on the light receiving means provided in the interchangeable lens for receiving the reflected light from the projected object, the distance measuring means provided in the camera body, and the output of the light receiving means, the object is closer than a predetermined distance. When the processing means for outputting an output depending on whether the subject is in the zone and the processing means output a signal indicating that the subject is in the zone, the photographing lens is moved to a predetermined position on the near distance side. And a drive control means for driving the taking lens to the in-focus position based on the output of the distance measuring means, the automatic focus adjusting device for the camera. (Invention 6) In Invention 5, a plurality of light projecting means and a plurality of light receiving means are provided. (Invention 7) In Invention 6, the light projecting means includes a first light projecting element having a narrow light projecting range and a second light projecting element having a wider light projecting range.
And a light projecting element. (Invention 8) In the above Invention 5, the light projecting means has a light projecting control means for causing the light projecting element to emit light intermittently. (Invention 9) In the above Invention 5, the light receiving means is intermittent from the light projecting means. It has an integrating means for integrating the reflected light from the subject of the projected light.

[0020]

As described above, according to the present invention, it is possible to perform a smooth focusing operation without performing an extra lens scan in the automatic focus adjustment with a lens capable of macro photography.

[Brief description of drawings]

FIG. 1 is an overall view showing an embodiment of the present invention.

FIG. 2 is a circuit block diagram of an embodiment of the present invention.

FIG. 3 is a schematic front view of an embodiment of the present invention.

FIG. 4 is a schematic front view showing the operation of the light shielding member in the embodiment of the present invention.

FIG. 5 is a perspective view showing a configuration of a light shielding member according to an embodiment of the present invention.

FIG. 6 is a plan view showing a subject distance determining operation according to an embodiment of the present invention.

FIG. 7 is a chart showing the operation of the circuit according to the embodiment of the present invention.

FIG. 8 is a diagram showing a flow chart of a circuit according to an embodiment of the present invention.

FIG. 9 is a circuit block diagram showing another embodiment of the present invention.

FIG. 10 is a diagram showing a light emitting state of a circuit according to another embodiment of the present invention.

FIG. 11 is a chart showing the operation of the circuit according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 lens 2 camera body 4 distance measuring section 12 lens drive control means 13a, 15a light projecting elements 13b, 15b light receiving element 17 lens CPU 21 body CPU

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03B 7/20 17/14

Claims (3)

[Claims] 1. An automatic focus adjusting device for a camera in which an interchangeable lens capable of macro photography can be mounted, and a projecting means provided on the interchangeable lens capable of macro photography and projecting light onto an object, and the macro photography being possible. Based on the light receiving means provided in the interchangeable lens for receiving the reflected light of the projected light from the subject, the distance measuring means provided in the camera body, and the output of the light receiving means, the subject is closer than a predetermined distance. And the determining means determines that the subject is closer than the predetermined distance, the photographing lens is driven to a predetermined position on the shorter distance side, and then the distance measuring is performed. An automatic focus adjusting device for a camera, comprising: a lens drive control unit that drives a taking lens to a focus position based on an output from the unit. 2. The automatic focus adjusting device for a camera according to claim 1, wherein the determining means is provided in the taking lens. 3. An auto-focusing type camera having a distance measuring means, a macro photographing lens having a light projecting means and a light receiving means on the front surface, and a subject within a macro photographing area based on the output of the light receiving means. If it is determined that the subject is within the macro photography area based on the output of the above determination means, the photographing lens is pre-driven to a predetermined distance within the macro photography area. After that, the automatic focusing camera is characterized in that it is driven to the in-focus position based on the output of the distance measuring means.