JPH05257054A - Camera system - Google Patents

Abstract

PURPOSE:To surely display the performance of a conversion lens by preventing the erroneous use of a user when the conversion lens is attached to the top end of a lens and used. CONSTITUTION:The contact points 75a and 75b are provided on the conversion lens, and a resistor 163 whose resistance value is varied according to the kind of conversion lens is connected with both contact points. A voltage divided by the resistor 163 and the resistor 162 of a camera side, is read by the CPU 150 of a camera, so that the fitting of the conversion lens and its kind are confirmed on the camera side. Thus, optimum performance can be displayed, for a focal distance at the time of fitting the conversion lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera system, and more particularly to a camera system in which a conversion lens is detachably attached to the front end of the lens of the camera.

[0002]

2. Description of the Related Art A conversion lens that can be detachably attached to the front end of a lens mounted on a camera includes a tele conversion lens for extending the focal length, a wide conversion lens for shortening the focal length, and an even shorter lens. There is a macro conversion lens (close-up lens) to shorten the shooting distance.

The tele-conversion lens is often used for sports photography, wildlife photography, etc., and is used for the purpose of obtaining a telephoto effect for a long-distance subject.

In order to provide a compact and inexpensive tele-conversion lens that satisfies this purpose, as shown in FIG. 20, focusing in a photographing optical system including a focusing lens 1, a variator lens 2 and a relay lens 3 is provided. Only when the lens 1 is used in the extended amount range from the infinity shooting position to the predetermined position on the far distance side from the close-up end shooting position when the tele-conversion lens is not attached, sufficient depiction performance can be exhibited. Optimally designed. Therefore, when using the tele-conversion lens, it is necessary to confirm that the subject to be photographed is farther than the designated close-up distance (for example, 3 m) that is farther than the close-up distance (for example, 1 m) of the lens mounted on the camera. There is a need.

On the other hand, the wide conversion lens is used for the purpose of obtaining a wide-angle photographing effect. To satisfy the purpose, and to provide a small and inexpensive wide conversion lens, FIG. As shown, from the movement locus L1 at the infinity photographing position when the focusing lens 1 is focused to the movement locus L3 further closer than the movement locus L2 at the close-up end photographing position when the wide conversion lens is not attached. It is designed so that sufficient drawing performance can be exhibited in the range (the area shaded with a downward sloping left in the figure).

Further, the macro conversion lens is used for the purpose of approaching a subject to a distance that cannot be photographed by a lens mounted on the camera and obtaining a higher photographing magnification. Generally, as shown in FIG. 21, it is sufficient to use the focusing lens of the lens mounted on the camera at any position within the range of the extension amount from the infinity photographing position T to the close-up end photographing position W. It is designed to show the drawing performance. In this case, if the focusing lens 1 is designed so as to exhibit sufficient depiction performance even when extended by a predetermined amount from the close-up end shooting position W during normal shooting without the conversion lens attached,
More macro shooting effect can be obtained.

However, if the focusing lens of the camera is provided so as to be extended by a predetermined amount beyond the normal close-up end photographing position W, when the macro conversion lens is not used, it is erroneously attached only when the macro conversion lens is attached. There is a possibility that the focusing lens 1 may be extended to the allowable extension range, and a photograph with degraded image quality due to aberration collapse may be taken. Therefore, in reality, even when the macro conversion lens is attached, it is not possible to extend more than the amount that can be guaranteed when the conversion lens is not used.

[0008]

By the way, when a tele-conversion lens having a close-up distance specified on the far side from the close-up possible photographing distance of the lens mounted on the camera is used, the user is specified. You may forget to take the closest distance or make a mistake in your eyesight to shoot at a closer distance than the specified distance. In this case, the camera operates normally, but the photographed image is accompanied by a reduction in the amount of peripheral light and a deterioration in image quality due to the collapse of aberrations.

On the other hand, when a wide conversion lens is used, in order to prevent the above-mentioned misuse, although the wide-angle shooting can be performed, the shooting magnification is limited.

On the other hand, when a macro conversion lens is used, although there is a possibility that a higher magnification can be taken, the photographing magnification is unavoidably limited to prevent the above-mentioned misuse. ..

SUMMARY OF THE INVENTION An object of the present invention is to provide a camera system which solves the above-mentioned problems, prevents misuse by a user when using various conversion lenses, and can reliably exhibit the performance of various conversion lenses. .. Furthermore,
The aim is to provide a camera system that maximizes the capabilities of conversion lenses compared to conventional cameras.

[0012]

A camera system according to the present invention is an electric drive source, a focusing mechanism driven by the electric drive source, and Setting means for setting the focus distance by the focusing mechanism to a desired value, detection means for detecting the amount of extension of the focusing lens group in the photographing lens, and outputting a signal according to this extension amount, and attachment / detachment of the conversion lens A discriminating unit that discriminates at least one of a state and a type and outputs a discriminating signal, monitors the output of the detecting unit, controls the drive of the electric drive source based on the output of the setting unit, and outputs the discriminating signal of the setting. When inputting, the above drive control is performed depending on whether the conversion lens is attached or detached.
Alternatively, a control means for keeping the focus distance range within a focus range according to the type is provided, and
In a camera having a lens barrel in which a conversion lens is detachable, an electric drive unit for performing a focusing operation, a setting unit for setting a focus distance to a desired value, and a mounting unit for mounting the conversion lens,
While the mounting signal generating means for automatically or manually outputting the output and the electric driving means according to the output of the setting means are operated, the focus distance set when the conversion lens is mounted is an optically inappropriate focus distance. At some time, receiving the output of the mounting signal generating means,
And a control means for forcibly operating the electric drive means until an optically appropriate focus distance is achieved, and a camera having a lens barrel in which a conversion lens is detachable An electric drive unit for performing a focusing operation, a setting unit for setting a focus distance to a desired value within a predetermined range,
When mounting the conversion lens, the mounting signal generating means for automatically or manually outputting an output, and the electric drive means in response to the setting means output,
When the output of the mounting signal generating means is received, a control means for enlarging the predetermined range is provided, and an electric driving means for performing a focusing operation of the lens and a focus distance of the lens are set to a desired value. When the focusing distance is an optically inadequate distance, the normal driving for operating the electric drive means according to the output of the setting means A conversion lens used in a camera having a control means capable of forcibly driving the electric drive means, and having a signal generating means for causing the control means to perform the forcible drive. Is characterized by.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a longitudinal sectional view of an essential part of a camera 50 mainly showing a zoom lens barrel in the first embodiment in which the present invention is applied to a single-lens reflex camera, showing a state in which zooming is performed at the wide end. Indicates the optical axis. The left side is the subject side (hereinafter referred to as the front side), and the right side is the camera body side (hereinafter referred to as the mount side).

The zoom lens barrel 20a has a three-group structure including a focusing lens 1, a variator lens 2 and a relay lens 3. Then, as shown in FIG.
As indicated by 0 and 21, the focusing lens 1 and the variator lens 2 move back and forth in the optical axis direction to perform a zooming operation, and when the focusing lens 1 moves, a focusing operation is performed.

A fixed frame 15 for supporting the relay lens 3 of the zoom lens barrel 20a is fixed to the camera body 20, and an engaging pin 13a planted in an intermediate barrel 13 described later is provided in the center of the fixed frame 15 on the front side thereof. The second lens frame 14 which will be described later
The linear guide grooves 15a and 15b into which the engaging pin 14a that is planted are inserted. Then, the camera body 20, the lower cover 21, and the upper cover 22.
The lens barrel 20a is covered by the rear lid 23.

On the outer peripheral surface of the fixed frame 15, there is provided a cam frame 16 formed of a cylindrical body and comprising a zoom ring for performing a zooming operation, and on the inner peripheral surface thereof there is provided a second lens for supporting the variator lens 2. The frame 14 and an intermediate cylinder 13 described later are fitted together. A helicoid screw portion 13b is provided on the inner peripheral surface of the intermediate cylinder 13 and is screwed into the helicoid screw portion 12a of the first lens frame 12 that supports the conversion lens 1.

A movable half mirror 4 supported by a mirror shaft 11 is disposed behind the lens barrel 20a.
Focus screen 5, pentaprism 6, above
A viewfinder optical system including an eyepiece lens 7 is arranged. A movable auxiliary mirror 33, a focal plane shutter 8 and a film 9 are provided behind the mirror 4, and the film surface of the film 9 is regulated by a pressure plate 10 provided on a rear lid 23.

Further, below the auxiliary mirror 33, a focusing sensor 34 for detecting focusing by the reflected light reflected by the mirror 33 is arranged. In addition to this, a zoom encoder 55, which will be described later with reference to FIG. 3, is provided above the zoom lens barrel 20a, and a distance encoder is provided below the zoom encoder 55.
56 and an electric control device including a CPU 150 are provided.

The half mirror 4 is obliquely placed at an angle of 45.degree. With respect to the optical axis O as shown in the figure at the time of finder observation, and the half mirror 4 is composed of a focusing lens 1, a variator lens 2 and a relay lens 3. The light flux from the optical system is reflected on the focusing screen 5, and at the same time, a part of the light flux is transmitted and projected on the focusing sensor 34 via the auxiliary mirror 33. The light flux that has passed through the focusing screen 5 is observed as an erect image through the eyepiece 7 through the pentaprism 6.
On the other hand, during shooting, the half mirror 4 and the auxiliary mirror 33 are used.
Moves to a position retracted from the optical path range of the luminous flux, and an image is taken.

The engaging pin 13 is provided on the outer peripheral surface of the intermediate cylinder 13.
a is planted. The engagement pin 13a passes through the linear guide groove 15a of the fixed frame 15 and a cam frame 16 described later.
Is fitted in the spiral cam groove 16a. Meanwhile, the second
An engaging pin 14a is also planted on the outer peripheral surface of the lens frame 14, and is fitted into the spiral cam groove 16b of the cam frame 16 via the straight guide groove 15b of the fixed frame 15.

A gear 17c fixed to the output shaft of the zoom motor 17 meshes with a gear 16c provided on the outer peripheral surface of the cam frame 16 near the mount.
The rotation of 7 performs the zooming operation. That is, in order to zoom to a wide angle, the cam frame 16 is rotated clockwise when viewed from the front side. Then, the engagement pins 13a, 14
a is driven in the optical axis direction by the spiral cam grooves 16a, 16b of the cam frame 16 while being linearly guided in the optical axis direction by the linear guide grooves 15a, 15b of the fixed frame 15.
The focusing lens 1 and the variator lens 2 are moved to a predetermined wide-angle zoom position to end the wide-angle zooming. At the same time, each contact piece of the zoom encoder switch 19 slides and moves on the encoder pattern 18, and the encoder 55 outputs an encoded output corresponding to the wide-angle position.

On the other hand, for zooming to the telephoto side, that is, the long focus side, the cam frame 16 is rotated counterclockwise as viewed from the front side. By the rotation, the engagement pins 13a and 14a are driven in the optical axis direction by the cam grooves 16a and 16b while being guided straight, and the focusing lens 1 and the variator lens 2 are moved to a predetermined telephoto position to end the telephoto zooming. To do. Zoom encoder switch 1 at the same time
Similarly to the case of the wide-angle zoom, each of the contact pieces 9 also slides on the encoder pattern 18 and the encoder 55 outputs an encoded output corresponding to the telephoto position.

As shown in FIG. 3, the zoom encoder 55 is composed of a zoom encoder pattern 18 provided on the cam frame 16 and a zoom encoder switch 19 fixed to the upper cover 22. A zoom encoder pattern 18 including a conductive pattern 18a and an insulating pattern 18b is arranged on the outer periphery of the rear of the cam frame 16, and an encoder switch 19 is provided at a position corresponding to the pattern 18.
The switch 19 is fixed to the upper cover 22 so that the switch is disposed. Then, the common piece 19a and the pieces 19b, 19c, 19d are slid on the pattern 18. As a result, when the cam frame 16 rotates due to the zooming operation, the encoder switch 19 outputs a zoom signal.

A gear 24a fixed to the output shaft of a focusing motor 24 meshes with a gear 12d provided on the outer peripheral surface of the first lens frame 12, and the rotation of the focusing motor 24 causes the lens frame to rotate. 12
Is guided in the helicoid screw portion 13b of the intermediate barrel 13 and is extended in the optical axis direction for focusing operation.

A comb-teeth-shaped rotating body 24b shown in FIG. 4 is fixed to the output shaft of the focusing motor 24. A photo interrupter 25 is arranged in which a light emitting portion and a light receiving portion are arranged to face each other across the passage of the rotating body 24b, and the comb-shaped rotating body 24b and the photo interrupter 25 are arranged.
The rotation amount of the focusing motor 24 is detected by the distance encoder 56 composed of

Further, the front end portion of the first lens frame 12 is
It has a mount shape to which a conversion lens to be described later can be mounted, and a key groove 12c for positioning the conversion lens in the rotation direction shown in FIG.
A fixed contact 26 including contacts 26a and 26b for determining the type of the conversion lens and the presence / absence of attachment / detachment is provided.

6 and 7 are a sectional view and a rear view of the wide conversion lens 70 mounted on the camera 50 . The lenses 71, 72, 73 are fixed to a fixed frame 74. The rear end of the fixed frame 74 has a mount shape for mounting on the camera, and fits on the key 74b that can be fitted into the key groove 12c (see FIG. 5) of the camera and the inner diameter portion 12b of the lens frame 12 of the camera. Protrusion 7 with an outer diameter that can fit
4a are provided respectively.

Further, at the rear end of the fixed frame 74 of the wide conversion lens 70, a movable contact 75 composed of contacts 75a and 75b pressed backward by a compression coil spring 76.
Are provided, and when attached to the camera,
It is arranged at a position in contact with the contacts 26a and 26b (see FIG. 5) of the camera. Further, between the contact points 75a and 75b, a resistance 163 peculiar to the wide conversion lens determined by the type of the conversion lens (see FIG.
(See) is connected.

FIG. 8 shows the above wide conversion lens.
FIG. 7 is a cross-sectional view showing a state in which 70 is attached to the camera 50 , and the camera is in a state where the focal length is at the wide end due to an operation sequence described later. On the other hand, FIG. 9 shows a state in which the teleconversion lens 60 is attached to the camera 50 . Here, in the tele conversion lens 60 , lenses 61 and 62 are fixed to a fixed frame 63, and a rear end portion of the fixed frame 63 has the same shape as the wide conversion lens 70 . The movable contact 64 composed of two contact points and the compression coil spring 65 have the same structure, but a resistor having a resistance value specific to the teleconversion lens is connected between the two movable contacts 64. There is. Also, the camera has a focal length at the tele end due to the operation sequence described later, and the zoom encoder 5 at that time
5 and the cam frame 16 are as shown in FIG.

Incidentally, reference numeral 12 in FIGS.
Reference numerals 0 and 121 denote permanent magnets and their adsorbing members, which maintain the mounted state when the conversion lens is mounted on the tip of the zoom lens barrel. This suction force is set to a strength such that the two can be separated manually. Needless to say, this suction state maintenance is not limited to the above suction method, and various known methods such as a known bayonet mounting method and a screwing method can be adopted.

Next, the configuration of the electric circuit in the first embodiment will be described with reference to FIG. 1. The circuits of the first embodiment are sequence-controlled by the CPU 150. Input terminal C of CPU 150
The tele-zoom switch 168a and the wide-zoom switch 168b, which are respectively connected to C14 and C15, are external operation switches for performing the zooming operation of the photographing lens, and when the tele-zoom switch 168a is turned on,
The CPU 150 determines that this is a zooming operation command to the long focus side, sets the output terminal C2 to the "L" level, and the output terminal C4.
To "H" level.

Then, since the transistors 152 and 155 are turned on, the zoom motor 17 is normally rotated by the current supplied from the battery 151 in the direction of the arrow A ₁ , and the zooming operation to the long focus side is performed. And the tele zoom switch 1
68a is turned off, or the taking lens is moved to the longest focal point side, and the common contact piece 19a and the contact pieces 19b, 19c, 19
and a zoom encoder 55 (see FIGS. 2 and 3).
The input terminal C10 of the CPU 150 indicates that all of the zoom encoder switches 19 for detecting the state of
The above zooming operation continues until C11 and C12 detect.

On the other hand, when the wide zoom switch 168b is turned on, the CPU 150 determines that this is a zooming operation command to the short focus side, and sets the output terminal C3 to the "H" level,
C5 is set to "L" level. Then, the transistor 15
Since 3 and 154 are turned on, the zoom motor 17 is reversely rotated this time, and the zooming operation to the short focus side is performed. Then, the CPU 150 indicates that the wide zoom switch 168b is turned off, or that the photographing lens is at the shortest focus side and all the zoom encoder switches 19 are turned on.
The above zooming operation continues until is detected.

The release switch 160 connected to the input terminal C13 of the CPU 150 is an external operation switch. When the release switch 160 is turned on, the CPU 150 determines that this is a release operation command and performs a release operation.

Next, an electric circuit of means for detecting the amount of extension of the focusing lens 1 by the photo interrupter 25 of the distance encoder 56 will be described. In FIG. 1, reference numeral 166 is a waveform shaping circuit for shaping the signal from the photo interrupter 25 and outputting it to the up / down counter 167.

Now, the CPU 150 outputs the output terminal C21.
Is set to the “H” level, the LED 164 included in the photo interrupter 25 is turned on. Therefore, the waveform shaping circuit 166 shapes the signal current from the phototransistor 165 and outputs a square wave pulse to the up / down counter 167.

The CPU 150 controls up / down of the up / down counter 167 by controlling the output level of the output terminal C16 corresponding to the rotation direction of the focusing motor 24. Also C
The PU 150 reads the count value from the up / down counter 167 from its input terminals C17 to C20. This count value corresponds to the amount of extension of the focusing lens 1, and the absolute value of the amount of extension of the focusing lens 1 is detected by resetting the up / down counter 167 at the position where the focusing lens 1 is most extended. be able to.

The focusing sensor 34 is a sensor for detecting the defocus amount and the defocus direction of the lens. By the output of the focusing sensor 34, the CPU 1
When the CPU 50 determines that the focusing lens 1 is to be extended by a predetermined amount, the CPU 150 sets the output terminal C6 to "L".
The level and output terminal C8 are set to "H" level. Then, the transistors 156 and 159 are turned on, so that the battery 151
The focusing motor 24 rotates in the forward direction by the current flowing in the direction from the arrow B ₁ to the focusing direction in the feeding direction. And distance encoder 56 (see FIG. 2)
The focusing operation is continued until the focusing lens 1 is extended to the target position by the output from.

On the other hand, when the CPU 150 determines from the output of the focusing sensor 34 that the focusing lens 1 is retracted by a predetermined amount, the CPU 150 outputs the output terminal C.
7 is set to "H" level and C9 is set to "L" level. Then, since the transistors 157 and 158 are turned on, the focusing motor 24 is rotated in the reverse direction this time, and the focusing operation in the retraction direction is performed. And the distance encoder 5
The focusing operation is continued until the focusing lens 1 is moved to the target position by the output from 6 .

The sequence drive circuit 161 includes a drive mechanism for the movable reflection mirror 4 and the movable reflection auxiliary mirror 33 (see FIG. 2), a known photometry and aperture drive mechanism, a shutter charge mechanism, and a film winding mechanism for the CPU 15.
It is a circuit operated by a signal of 0.

Next, a circuit for discriminating the type of the mounted conversion lens will be described. When the CPU 150 sets the output terminal C22 to the "H" level and applies the reference voltage, the voltage divided by the predetermined resistor 162 and the resistor 163 determined by the type of conversion lens is the input terminal which is the A / D port. Input to C1. As a result, the CPU 150 can detect the type of conversion lens and the presence / absence of attachment / detachment.

The photographing sequence of the first embodiment thus constructed will be described with reference to the flowcharts of FIGS. Although both FIGS. 11 and 12 form one flow chart, since the space is limited due to the electronic application, the flow chart is divided into two, and the connection between the drawings is a, b, c, d. Represented by. Further, each conversion lens in the present embodiment is compact and optimally designed to be used in the following areas in order to exert sufficient drawing performance.

That is, the tele conversion lens 60 is
Since it is used for the purpose of obtaining a telephoto effect that cannot be obtained with the zoom lens mounted on the camera, sufficient depiction performance can be exhibited only when the zoom lens of the camera is used at the telephoto end. Further, since the wide conversion lens 70 is used for the purpose of obtaining a wide-angle effect that cannot be obtained by the zoom lens mounted on the camera, sufficient depiction performance is exhibited only when the zoom lens of the camera is used at the wide end. it can. Furthermore, the amount of extension of the focusing lens 1 varies depending on each conversion lens, and is an amount that sufficiently satisfies the usage conditions of each conversion lens. In particular, the macro conversion lens is used for the purpose of obtaining a higher shooting magnification by approaching the subject to a distance that cannot be captured by the lens mounted on the camera, so the extension amount is more than the limit extension amount of the camera alone. It is possible to increase the number of close-up shots.

In FIG. 11, when this flow starts, first, in step # 101, the CPU 150 determines whether or not the tele-conversion lens is mounted. In step # 102, the output of the zoom encoder 55 determines whether or not the focal length is at the tele end. If not, the zoom motor 17 is driven in # 103 to zoom to the tele end.

Then, in step # 104, the count value of the up / down counter 167 (see FIG. 1) is monitored to judge whether the amount of extension of the focusing lens 1 is within the range of the amount of extension when the teleconversion lens is attached. If it is out of the above range, the focusing motor 24 is driven in # 105 to move the focusing lens 1 to the allowable closest end.

Next, at # 106, the on / off state of the release switch 160 is monitored. If the release operation is not performed and it is in the off state, the start position of the flowchart, that is, #
Return to 101. On the other hand, when it is detected that the release switch 160 is turned on, the output of the focusing sensor 34 is monitored at # 107 and # 108, and the moving amount of the focusing lens 1 is calculated from the defocus direction and the value of the defocus amount. Then, it is determined whether or not the amount of extension of the focusing lens 1 after the movement is within the range of the amount of extension when the teleconversion lens is mounted.

If it is calculated that the value is out of the range, in step # 109, the teleconversion lens is extended to the permissible near end when the lens is mounted, and the process returns to the start of this flowchart. Therefore, the user can recognize the limit at the closest end because the camera does not proceed to the next operation, and can prevent erroneous shooting. On the other hand, if it is determined to be within the range # 108, the flow advances to # 141 in FIG. 12, the distance encoder 5
The focusing motor 24 is operated while monitoring 6 to move the focusing lens 1 to the calculated position to complete the focusing operation.

Next, the sequence drive circuit 161 is operated in steps # 142 to # 145 to perform a series of frame-by-frame shooting operations such as photometry, mirror up / aperture control, shutter drive, mirror down / aperture open / film roll up. To complete.

On the other hand, returning to step # 101 in FIG. 11 above, if the CPU 150 determines that the teleconversion lens is not mounted, then the mounting state of the wide conversion lens is determined in step # 111. If you decide to install a wide conversion lens here, # 1
At 12, it is determined whether the focal length is at the wide end based on the output of the zoom encoder 55. If not, the zoom motor 17 is driven at # 113 to zoom to the wide end.
Next, in # 114, the count value of the up / down counter 167 is monitored to determine whether the amount of extension of the focusing lens 1 is within the range of the amount of extension when the wide conversion lens is attached. Is driven and the focusing lens 1 is retracted to the permissible closest end.

Next, at # 116, the on / off state of the release switch 160 is monitored, and if it is in the off state where the release operation is not performed, the process returns to the start position of this flowchart, that is, # 101. On the other hand, when it is detected that the release switch 160 is turned on, the output of the focusing sensor 34 is monitored at # 117 and # 118, and the movement amount of the focusing lens 1 is calculated from the defocus direction and the value of the defocus amount. Then, it is determined whether or not the amount of extension of the focusing lens 1 after the movement is within the range of the amount of extension when the wide conversion lens is mounted.

If it is calculated that the value is out of the range, in step # 119, the process is extended to the allowable close end when the wide conversion lens is mounted, and the process returns to the start of this flowchart. Therefore, the user can recognize the limit at the closest end because the camera does not proceed to the next operation, and can prevent erroneous shooting.

On the other hand, if it is determined in # 118 that it is within the above range, the process proceeds to # 141 in FIG.
The focusing motor 24 is operated while monitoring 56, and the focusing lens 1 is moved to the calculated position to complete the focusing operation. Next, a series of operations are completed in # 142 to # 145 as in the case of mounting the teleconversion lens.

Returning to step # 111, the CPU 15
If it is determined that the wide conversion lens is not attached at 0, then the attachment state of the macro conversion lens is determined at step # 121. If it is determined here that the macro conversion lens is attached, the macro conversion lens in this embodiment can be used in the entire range of the focal length of the zoom lens mounted on the camera, and the focusing lens 1 can be used more than other states. Since the design is such that the amount of extension can be large, the process proceeds to step # 122 without monitoring the focal length or the amount of extension.

Next, at # 122, the on / off state of the release switch 160 is monitored. If the release operation is not being performed, the flow returns to the start of the flowchart. On the other hand, if it is detected that the release switch 160 is on, # 12
The output of the focusing sensor 34 is monitored at 3 and # 124, and the moving amount of the focusing lens 1 is calculated from the values of the defocus direction and the defocus amount. Then, it is determined whether the amount of extension of the focusing lens 1 after the movement is within the range of the amount of extension when the macro conversion lens is attached.

If it is calculated that the value is out of the above range, in step # 125, the process is extended to the allowable close end when the macro conversion lens is mounted, and the process returns to the start of the flowchart. Therefore, since the user does not proceed to the next operation, the user can recognize the limit at the closest end and can prevent erroneous shooting. On the other hand, when it is determined in # 124 that it is within the above range, the process proceeds to # 141, the focusing motor 24 is operated while monitoring the distance encoder 56, and the focusing lens 1 is moved to the calculated position to perform the focusing operation. To complete. Then, a series of operations are completed in # 142 to # 145 as in the case of mounting other conversion lenses.

Returning to step # 121, the CPU 15
When it is determined that the macro conversion lens is not attached at 0, the CPU 150 recognizes that the camera is in a standard state in which various conversion lenses are not attached. Then, by monitoring the count value of the up / down counter 167 in # 131 of FIG. 12, it is determined whether or not the amount of extension of the focusing lens 1 is within the range of the amount of extension in the standard state, and it is out of the range. When # 13
The focusing motor 24 is driven at 2 to move the focusing lens 1 up to the allowable close end.

Next, at # 133, the on / off state of the release switch 160 is monitored, and if the release operation is not performed and it is in the off state, the process returns to the start of the flowchart. On the other hand, if it is detected that the release switch 160 is ON, # 13
The output of the focusing sensor 34 is monitored at 4 and # 135, and the movement amount of the focusing lens 1 is calculated from the values of the defocus direction and the defocus amount. Then, it is determined whether or not the amount of extension of the focusing lens 1 after the movement is within the range of the amount of extension in the standard state.

If it is calculated that the value is out of the above range, in step # 136, the process is extended to the allowable close end in the standard state and the process returns to the start. Therefore, since the user does not proceed to the next operation, the user can recognize the limit at the closest end and can prevent erroneous shooting.

On the other hand, if it is determined in # 135 that it is within the above range, the process proceeds to # 141, the focusing motor 24 is operated while monitoring the distance encoder 56, and the focusing lens 1 is moved to the calculated position. The focusing operation is completed. Then, as in the case of mounting the conversion lens, a series of operations are completed at # 142 to # 145.

According to the first embodiment described above, various conversion lenses, which are small in size and low in price by limiting the usable distance from the camera to the subject at the time of shooting, are attached to the front end of the lens of the camera. When using
It is possible to automatically prevent misuse such that the user shoots at a distance other than the specified distance to the subject, and it is possible to reliably exhibit the performance of various conversion lenses. Furthermore, even if the amount of extension of the focusing lens group is equal to or greater than the maximum amount of extension of the focusing lens group, which corresponds to the shortest possible shooting distance of the lens mounted on the camera,
Only when using a conversion lens that can exhibit sufficient performance at the front end of the camera, maximize the conversion lens capacity by increasing the amount of extension of the focusing lens group by a predetermined amount compared to when the conversion lens is not installed. Can be demonstrated.

FIG. 13 is a longitudinal sectional view of an essential part of a camera according to the second embodiment of the present invention. In the first embodiment, at least one of the attachment / detachment state and the type of the conversion lens is attached when the conversion lens is attached. While the determining means for determining and outputting the determination signal is composed of the resistor 163 (see FIG. 1), in the second embodiment, as will be described later, the lengths of the projections 76, 66 provided on the conversion lens are long. The difference from the first embodiment is the same as that of the first embodiment except for this point. Therefore, the same components are designated by the same reference numerals, and the description thereof will be omitted. Only the determination means will be described below. ..

FIG. 13 shows the front end of the lens in a standard state with no conversion lens attached, FIG. 14 shows the wide conversion lens attached, and FIG. 15 shows the teleconversion lens attached. In FIG. 13, a hole 12d is provided at the tip of the lens frame 12, and inside the hole 12d, as shown in FIG.
An identification switch 30 composed of three leaf contact pieces 30a to 30c is arranged. In this case, the leaf contact pieces are separated from each other in the standard state.

Each conversion lens is shown in FIGS.
As shown in Fig. 7, the protrusions 76 and 66 having the protrusion amount determined by the type of each conversion lens are provided, and the leaf sections 30a and 30b are electrically connected in the case of the wide conversion lens when mounted on the camera.
In the case of a tele-conversion lens, leaf sections 30a, 3
0b and 30c are all conductive.

FIG. 17 is a block diagram showing an essential part of the electric circuit of this embodiment. The identification switch 30 is a common contact piece 30a.
And contact pieces 30b, 30c, and contact pieces 30b, 30c
Are connected to the input terminals C29 and C30 of the CPU 150, respectively. With the above configuration, the camera can determine the attachment / detachment state and type of the conversion lens,
The same operation as that of the first embodiment can be performed.

According to the second embodiment, since it is not necessary to provide a movable contact or a resistor on each conversion lens, it is possible to provide a smaller and cheaper conversion lens than that of the first embodiment. Further, although there are two types of conversion lenses in the present embodiment, it is possible to cope with many types of conversion lenses by increasing the number of leaf contact pieces.

FIG. 18 is a block diagram showing an essential part of an electric circuit of a camera according to the third embodiment of the present invention. In the third embodiment, each conversion is performed as a means for discriminating the attachment / detachment state and type of the conversion lens. A ROM 168 indicating the type is provided in the lens, and the CPU 150 in the camera is provided.
The same discrimination operation as in each of the above-described embodiments is performed by communicating with the above. Except for this point, there is no difference from each of the above-mentioned embodiments, and the description thereof will be omitted.

According to the third embodiment described above, the number of types of conversion lenses can be significantly increased only by changing the contents of the ROM 168, and in addition to the types of conversion lenses, the transmittance of the lenses and the FNo. By storing the AE-related information such as, the AF correction coefficient, and the like, more detailed automatic control using information unique to each conversion lens becomes possible.

FIG. 19 is a block diagram showing an essential part of an electric circuit of a camera according to the fourth embodiment of the present invention. In the fourth embodiment, the means for discriminating the attachment / detachment state and type of the conversion lens is incorporated in the camera. Manual input switch 31,3
2 and 33 are provided, and the same operation as in the first embodiment is performed depending on the states of these switches.

That is, reference numeral 31 is a teleconversion lens mounting switch, 32 is a wide conversion lens mounting switch, and 33 is a macro conversion lens mounting switch. When all the switches are off, the conversion lens is not mounted in the standard state. Is. One end of each switch is a common contact piece, and the other end is connected to the input terminals C31, C32, C33 of the CPU 150 in the camera. With the above configuration, by manually switching the switches, the camera can determine whether or not the conversion lens is attached / detached and the type, and the same operation as in the first embodiment can be performed.

According to the fourth embodiment described above, it is not necessary to take any special countermeasures such as providing electric parts or mechanical parts inside the conversion lens or in the connection mount between the conversion lens and the camera. It is possible to provide a conversion lens and a camera that are smaller and cheaper than the above.

In all of the above-mentioned first to fourth embodiments, means for discriminating the type of conversion lens and presence / absence of attachment / detachment are provided. However, when only one type of conversion lens can be attached to the camera, only the attachment / detachment state thereof It suffices if there is a means to determine. Further, although the example applied to the single-lens reflex camera has been described, the present invention is not limited to this and can be widely applied to all kinds of cameras.

In each of the above embodiments, the use state of the zoom lens of the camera is limited to the tele end when the tele conversion lens is attached, and the wide end is attached when the wide conversion lens is attached. Depending on how the lens is used, it can be used within a region having a predetermined focal length or a predetermined range such as near the telephoto end or near the wide end.

[0073]

As described above, according to the present invention, it is possible to provide various conversion lenses which are compact and inexpensive by limiting the usable distance from the camera to the subject at the time of shooting. When the lens is attached to a part and used, it is possible to prevent erroneous use in which the user shoots at a distance other than the specified distance to the subject, and it is possible to reliably exert the performance of various conversion lenses.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of an electric circuit in a camera system showing a first embodiment of the present invention.

FIG. 2 is a longitudinal cross-sectional view of a main part of the camera at the time of widening in the first embodiment.

3 is a development view of the cam frame in FIG.

FIG. 4 is a front view of the distance encoder in FIG.

5 is a diagram illustrating a front end portion of the first lens frame in FIG.

6 is a sectional view of a wide conversion lens mounted on the camera shown in FIG.

7 is a rear view of the wide conversion lens shown in FIG.

8 is a cross-sectional view of the wide conversion lens shown in FIGS. 6 and 7 mounted on the camera shown in FIG.

FIG. 9 is a sectional view showing a state in which a tele-conversion lens is attached to the camera at the time of telephoto in the first embodiment.

10 is a development view of the cam frame in FIG. 9 described above.

FIG. 11 is a flowchart of a shooting sequence in the first embodiment.

FIG. 12 is a flowchart of a shooting sequence in the first embodiment.

FIG. 13 is a longitudinal sectional view of a main part of a camera according to a second embodiment of the present invention.

FIG. 14 is a longitudinal sectional view of a main part when a wide conversion lens according to the second embodiment is mounted.

FIG. 15 is a vertical cross-sectional view of a main part when a tele-conversion lens is attached in the second example.

FIG. 16 is a diagram illustrating an identification switch according to the second embodiment.

FIG. 17 is a block diagram of a main part of an electric circuit according to the second embodiment.

FIG. 18 is a block diagram of a main part of an electric circuit of a camera according to a third embodiment of the present invention.

FIG. 19 is a block diagram of a main part of an electric circuit of a camera according to a fourth embodiment of the present invention.

FIG. 20 is a diagram for explaining the movement of each lens in each of the above embodiments.

FIG. 21 is a view for explaining the movement of each lens in each of the above embodiments.

[Explanation of symbols]

12a, 13b ... Helicoid screw part (focusing mechanism) 24 ... Focusing motor (electric drive means, electric drive source) 24b ... Comb-shaped rotor (detection means) 25 ... Photointerrupter (detection means) 26 ... Fixed contact (discrimination means) ) 34 ... Focusing sensor (setting means) 75 ... Movable contact (determination means) 150 ... CPU (control means, setting means) 163 ... Resistance (determination means)

Claims (4)

[Claims] 1. A camera in which a conversion lens can be attached to and detached from the end of a photographing lens, an electric drive source, a focusing mechanism driven by the electric drive source, and a setting for setting a focus distance by the focusing mechanism to a desired value. Means for detecting the amount of extension of the focusing lens group in the photographing lens and outputting a signal according to the amount of extension, and at least one of the attachment / detachment state and type of the conversion lens, and a determination signal And the output of the detection means to control the drive of the electric drive source based on the output of the setting means, and at the time of inputting the determination signal, the drive control is performed to determine whether the conversion lens is attached or detached. Alternatively, a control means for keeping the focus distance range that can be photographed according to the type, A camera comprising: 2. A camera having a lens barrel to which a conversion lens is attachable / detachable, electric drive means for performing a focusing operation, setting means for setting a focus distance to a desired value, and when the conversion lens is attached. , A mounting signal generating means for automatically or manually outputting an output and the electric driving means in accordance with the output of the setting means, and when the conversion lens is mounted, the set focus distance is an optically inappropriate focus distance. And a control means for receiving the output of the mounting signal generating means and forcibly operating the electric drive means until the mounting signal generating means outputs an optically appropriate focus distance. A detachable camera. 3. A camera having a lens barrel to which a conversion lens is attachable / detachable, electric drive means for performing a focusing operation, setting means for setting a focus distance to a desired value within a predetermined range, When the conversion lens is mounted, the mounting signal generating means that automatically or manually outputs an output and the electric drive means are operated according to the output of the setting means, and the predetermined range is expanded when the output of the mounting signal generating means is received. A camera with a detachable conversion lens, characterized by comprising: 4. Electric drive means for performing a focusing operation of a lens, setting means for setting a focus distance of the lens to a desired value, and normal drive for operating the electric drive means according to the output of the setting means. A camera having a control means capable of forcibly driving the electric drive means until the focus distance is an optically inappropriate distance until the focus distance becomes an optically appropriate distance. A conversion lens for use in, comprising a signal generating means for forcibly driving the control means.