JPH01248115A - Automatic focusing adaptor - Google Patents

Abstract

PURPOSE:To improve operability by constituting the above adaptor so that a conversion lens group is driven in an optical axis direction by a motor to be set in a reference position by interlocking with a mode changeover switch. CONSTITUTION:When the mode changeover switch 23 is in an AF mode, a CPU 12 operates the moving quantity of the conversion lens group L necessary for focusing based on the detection signal of a focus detecting mechanism 11. According to the operated result, the motor M1 is driven to move the conversion lens group L in the optical axis direction so as to perform focusing. When the mode changeover switch 23 is in an MF mode, the CPU 12 judges the position of the conversion lens group L based on the detection signal of the optical system position detecting means 22 of the conversion lens group L and drives the motor M1, then stops the motor M1 at the time of attaining an infinity position which is the reference position. Thus, the operability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention is an autofocus Node A adapter, which incorporates a conversion lens group that is driven for focus adjustment, and which has an intervening lens between an interchangeable lens and a camera body. The present invention relates to an automatic focusing adapter that is equipped with an automatic focusing adapter.

``Prior Art'' An automatic focusing adapter has a convergecon lens group and a lens drive system that moves the conversion lens group in the optical axis direction.

The structure of the lens drive system is one that has a drive motor inside the automatic focus adjustment adapter and drives the conversion lens group via a gear reduction system, and one that does not have a drive motor inside the automatic focus adjustment adapter. The rotational output of the heart motor, which is the power source inside the body, is transmitted to the automatic focus adjustment adapter by a coupling mechanism, etc., and the automatic focus 1AfIJ
There are two types of lenses that drive the conversion lens group via a gear reduction system inside the attacher.

Then, the drive mechanism operates according to the amount of movement of the conversion lens group calculated based on the detection signal from the focus detection mechanism within the camera body, and automatically drives the conversion lens group to perform focus adjustment.

In either case, the conversion lens group of the autofocus adapter is configured to move in the optical axis direction for focus adjustment and stop when the subject is in focus, and the conversion lens group is always at an unspecified position. It will stop.

If you try to use this automatic focusing adapter as a normal teleconverter where the conversion lens group is fixed and focus adjustment is performed using the distance ring of the interchangeable lens, the stopping position of the conversion lens group will be set to the reference position at infinity. You have to make sure that it is in a position where you can focus it.

However, as mentioned in L, since the automatic focus adjustment adapter moves the conversion lens group to adjust the focus, there is no guarantee that the conversion lens group will always stop at the standard position (depending on the distance of the interchangeable lens). No matter what position the ring is moved to, the inconvenience arises that it may be impossible to focus on an infinite or long distance.

Therefore, a mechanism as shown in Fig. 9 was proposed in Japanese Patent Application No. 59-616.
No. 97 has been proposed.

FIG. 9 is a perspective view of the lower part of the automatic focus adjustment adapter, in which an operation dial 2 protruding from the outside of the adapter body l is provided.
The operating wheel 2 is separated from the gear train by the cup link 3 when the motor 4 is being driven, and is directly connected to the gear train when the motor is not being driven.

By rotating the operation dial 2 by T-motion, the conversion lens group is moved in the optical axis direction and set to infinity.

Furthermore, Japanese Patent Application No. 59-79063 proposes a mechanism as shown in FIG. 1O.

That is, a lever 4 for returning to the reference position is provided, and the lever 4 is rotatable around the A axis on the outer frame of the conversion lens group, or has a click (not shown) provided therein so that it can be moved back to a predetermined position. It is designed so that it will not rotate around the A-axis unless a force acts on it, and when the lever 4 itself revolves around the B-axis, which is the optical axis, together with the outer frame, only the conversion lens group rotates between the optical axes, and the optical axis can be moved in the direction.

Further, in the interchangeable lens 5, a protrusion 6a is provided on the rear protection ring 6 so as to come into contact with the lever 4.

Then, attach the interchangeable lens 5 to the adapter body l in the direction of the optical axis.
When the lens is inserted into the lens and rotated in the D direction to attach it, the protrusion 6a of the interchangeable lens first engages with the lever 4, and the lever 4 is hooked with a force smaller than the click force, rotating the conversion lens group in the optical axis direction. let

When only the conversion lens group hits the M1 limit (not shown), rotation of the conversion lens group in the optical axis direction is prohibited, and when the interchangeable lens 5 is rotated even more strongly, the lever 4 is applied with a predetermined force. The lever 4 and the protrusion 6a are engaged or disengaged, and the interchangeable lens 5 is rotated further between the optical axes, and at a predetermined angular position, the 31 autofocus adapters are rotated in the E direction around the A axis. fully equipped.

Immediately after attaching the interchangeable lens, the conversion lens group is always automatically set to the reference position and can be used as a normal teleconverter as described above11.

"Problem to be Solved by the Invention" However, the above-mentioned conventional technology does not allow the conversion lens group of the automatic focusing adapter to be converted into a J! Is it possible to return to the quasi-position? There are still problems as follows.

That is, in the conventional example shown in FIG. 9, after autofocus (hereinafter referred to as AF) operation, it is necessary to switch to manual focus (hereinafter referred to as MF) mode and use the automatic focus adjustment adapter as a normal teleconverter. , the conversion lens group must be moved to the infinite position by manually operating the operation dial.

In other words, when switching from AF mode to MF mode, it is necessary to perform two manual operations: switching the mode and moving the conversion lens group to a predetermined position, which not only impairs operability but also makes it easy to make mistakes in sudden operations. The rotational nature of the lens is also large, and the mechanism within the automatic focus adjustment adapter is also complicated.

In addition, in the conventional example shown in Fig. 1O, the conversion lens group is always automatically set to a predetermined position immediately after the interchangeable lens is attached, but once the AF operation is performed, the conversion lens group is set to an unspecified position. After that, in order to use the autofocus 3J section adapter as a teleconverter in MF mode, the interchangeable lens must be reattached, which is a complicated operation.

The unreleased Ill was made by focusing on these conventional problems.If you switch from AF mode to MF mode after AF operation and interrupt MF operation, the automatic focus adjustment adapter will immediately convert. Provides an autofocus adapter that improves operability for setting the position of the conversion lens group by allowing the autofocus adapter to be set at the reference position of the lens group and used as a normal teleconverter. It is intended to.

"L stage for solving three problems" The gist of the present invention for achieving the above objectives is: A conversion lens group ([,) movable in the axial direction, and a lens drive system (21) that automatically drives the conversion lens group (L) according to a focus detection signal.
an autofocus adapter (2) having at least a portion of
0), when the mode changeover switch (23) for switching between autofocus mode and manual focus mode and the mode changeover switch (23) are operated to manual focus mode, the conversion lens group (
An automatic focusing adapter for an interchangeable lens, comprising: a setting means for automatically positioning L) at a reference position by the lens drive system (21).

2. A conversion lens group (L) that is interposed between the camera body (10) and the interchangeable lens (30) and is movable in the optical axis direction, and a conversion lens group (L) that is automatically moved according to a focus detection signal. At least a part of the lens drive system (2K) to drive an autofocus m-node adapter (20
), there is a mode selector switch (15) on the camera body (lO) that switches between autofocus mode and manual mode.
), and when the mode selector switch (15) is operated to the manual focus operation mode, the lens drive system (21) causes the conversion lens group (L
) is automatically positioned at a reference position.

3 Conversion lens group (L) position detection means (2
2) and a setting f stage that automatically positions the conversion lens group (L) at the reference position based on the position and the signal of the detection f stage (22). The present invention resides in an automatic focusing adapter for an interchangeable lens according to item 1 or 2.

"Function" In the invention set forth in claim 1, a mode changeover switch is provided in the autofocus adapter, and the mode changeover switch is used to switch the entire camera between the AF mode and the MP mode.

The mode changeover switch and the lens drive system that drives the conversion lens group are linked via a setting means.

That is, when the AF mode is switched to the MF mode, the setting means drives the conversion lens group to a reference position such as an infinity position, and stops the conversion lens group at the reference position.

After that, the conversion lens group is no longer driven by the motor, and the autofocus g4ftI adapter can also be used as a normal teleconverter.

In the invention set forth in claim 2, the mode changeover switch on the camera body is linked with the lens drive system that drives the conversion lens group, and when the AF mode is switched to the MF mode, the first setting is automatically turned off. - The conversion lens group in the point adjustment adapter is moved in the optical axis direction by the lens drive system, driven to the reference position, and then stopped. Thereby, autofocus &l! The 1m adapter can also be used as a regular teleconverter.

In the invention set forth in claim 3, the setting means compares the current position of the conversion lens group indicated by the signal of the position detection means with a reference position when the mode changeover switch switches from the AF mode to the MF mode. , the conversion lens group is moved in the optical axis direction by the lens drive system by the amount of the difference, and is driven to the reference position and then stopped. This allows the autofocus adapter to also be used as a regular teleconverter.

As described in 1, in the present invention, by interlocking the mode changeover switch and the drive system that drives the conversion lens group in the autofocus adapter, the camera stops at an unspecified position during AF operation. When using the conversion lens group in MF mode, when the mode selector switch is changed to MF mode, the conversion lens group is always automatically set to a predetermined infinity position.

When you want to perform MF operation, switch from AF mode to M.
Just by changing the mode changeover switch to F mode, you can always use the 1 moving point adjustment adapter as a normal teleconverter without any other operations. It is easy to operate, and there is almost no risk of making mistakes.

"Embodiments" Various embodiments of the present invention will be described below based on the drawings. Note that similar parts in each embodiment are denoted by the same reference numerals, and redundant explanation will be omitted. Further, since the basic structure of the autofocus adapter is the same as that of the conventional autofocus 31w1 adapter, explanation and illustration thereof will be omitted.

1 and 2 show a first embodiment of the invention.

The autofocus Wffi adapter 20 is interposed between the camera body IO and the interchangeable lens 30.

Inside the camera body 10, a focus detection mechanism 11, a CPU
12, a lens drive motor M1 and its drive circuit 13, and a lens drive system 14 that transmits the output of the motor M1 on the body side. The lens drive system 14 includes a speed reducer 14a and a coupling 14b for connection to the autofocus adapter 20.

The automatic focus adjustment adapter 20 is a coupling that connects the conversion lens group and the coupling 14b of the lens drive system 14 to receive the output of the motor M1 in the camera body 1O and move the conversion lens group in the optical axis direction. 21a and a gear reduction system 21b. : Prepared.

Furthermore, the automatic focus adjustment adapter 20 has an optical system position detection means 22 for the conversion lens group inside, and a mode changeover switch 23 that can be operated from the outside and switches the automatic focus adjustment adapter 20 between AF mode and MF mode. The adapter includes an in-adapter memory circuit 24 that receives information on the position of the conversion lens group from the optical system position detection means 22 and mode switching information from the mode switching switch 23.

The in-adapter memory circuit 24 has a memory circuit (when using the autofocus secondary barrel adapter 20 in MF mode) &? The infinity distance, which is the I position, is memorized and the automatic focus adjustment adapter 20
Lens drive system 21. Optical system position detection stage 22. The memory circuit 24 in the adapter is the CPU 1 of the camera body lO.
2, and the mode selector switch 23 is set to MF.
When the mode is operated, the conversion lens group is automatically positioned at the reference position by the lens drive system 14.21.

Next, the operation of the first embodiment will be described.

If the mode changeover switch 23 of the automatic focus adjustment adapter 20 is in the AF mode, and assuming that the mode changeover switch inside the body (not shown) is naturally in the AF mode, the internal memo 9 circuit in the automatic focus adjustment adapter 20 Information that the autofocus adapter 20 is in the AF mode is transmitted to the CPU l 2 in the body via the autofocus adapter 24 .

Based on the detection signal of the focus detection mechanism 11, the CPU 12
The output of the six motors Ml that calculates the movement record Δd of the conversion lens group necessary for focusing and drives the motor Ml according to the result is connected from the lens drive system 14 on the body side to the coupling 14b. The signal is transmitted to the automatic focus adjustment adapter 20 via the gear reduction system 21b of the lens drive system 21 and the coupling 21a, and then the conversion lens IT
Focus adjustment is performed by moving L in the optical axis direction.

If MF operation becomes necessary during AF operation, an MF interrupt occurs, and the operation proceeds as shown in the flowchart of FIG.

That is, in step l, the mode changeover switch 23 of the n moving point adjustment adapter 20 is set to the MF mode. Step 2
When the information that the mode is MF mode is transmitted to the CPU 12, in step 3, the CPU 12 detects the detection signal of the optical system position detection means 22 of the conversion lens group in the automatic focusing adapter 20. The position of the lens group is determined, and in step 4, the motor Ml is driven.

When the optical system position detecting means 22 is at infinity, step 2.3 is repeated green, and when the conversion lens group is at the infinity position, which is the reference position l, step 5 turns on the motor Ml. make it stop.

The infinity position of the conversion lens group means that when the distance ring of the interchangeable lens 30 is set to infinity, the object at infinity is in focus, and only the conversion lens group stops at the reference position. After that, CPU l 2
A motor drive prohibition IF command is issued to the motor drive circuit 13 regardless of the mode of the mode switch provided in the body or the detection signal from the focus detection mechanism 11, and the conversion lens group is fixed at the ) & semi-position. be done.

Through the following operations, the automatic focusing adapter 20 becomes optically equivalent to a normal teleconverter, and has normal focusing and uf functions using the distance ring of the interchangeable lens 30.

The third [X and the fourth UA indicate the second embodiment.

The automatic focus adjustment adapter 20a includes a motor M2 and a motor drive circuit 25 for driving the conversion lens group.
and a built-in lens drive system 26.
is connected to the motor M2 without providing a coupling, and the other configurations are the same as in the first embodiment.

Next, the operation of the second embodiment will be explained.

Mode selection switch 2 in automatic focus adjustment adapter 20a
3 or AF mode, the CPU 12 causes the camera body IO to operate in the AF mode based on the information from the memory circuit 24 in the adapter indicating that the camera is in the AF mode.

That is, the CPU 12 receives the detection signal from the seven-point detection mechanism 11 and moves the conversion lens group necessary for focusing! h is calculated, the result is transmitted to the automatic focus adjustment adapter 20a, and the motor M2 is driven via the motor drive circuit 25 thereof. The output of the motor M2 is transmitted by the lens drive system 26 on the adapter side, and moves the conversion lens group in the optical axis direction to perform focus adjustment.

If MP operation is required during AF operation, an MF interrupt occurs and the operation proceeds according to the flowchart of FIG.

When the mode changeover switch 23 in the automatic focus sub-barrel adapter 20a is set to MF mode in step 1, step 2
The information that it is in the MF mode is transmitted to the CPU I2. The CPU l 2 determines the position of the conversion lens group based on the detection signal of the optical system position detection means 22 of the conversion lens group in the automatic focus adjustment adapter 20a in step 3, and determines the position of the conversion lens group in the automatic focus adjustment adapter 20a in step 4. motor M2 is driven.

Step 3.4 determines the optical system position from the detection signal of the detection means 22 or from the conversion lens group L'lJ<'! # Indicates that it is at the extreme position. When only the conversion lens group reaches the infinite position, the motor M2 is driven or stopped in step 5, and after that, the conversion lens J7 is driven or stopped.
L is fixed at this level.

Through the above-described operation, the automatic focusing adapter 20a becomes optically equivalent to a normal teleconverter, and functions as a normal focusing unit using the distance ring of the interchangeable lens 30, as in the first embodiment.

Note that in the first and second embodiments, the optical system position detection means for the conversion lens group may be a mechanism that merely detects whether the conversion lens group is at an infinite position; An operation with exactly the same effect as the operation described is performed in 11P.

Furthermore, even if there is no optical system position detection means, if a rotation limit is set at the semi-position, the relationship between the moving direction of the conversicon lens group and the rotational direction of the motor is known, so it can be used from AF mode. When changing to MF mode, the CPU
If the conversion lens is driven toward the infinity position and stopped at the first rotation limit encountered, and if the drive circuit receives a command to prohibit motor drive from then on, the conversion lens group will stop at the reference position and the optical system position will change. The same effect as when there is a detection means can be obtained.

No. 51Z and No. 617I indicate the third embodiment.

Inside the camera body 10, a focus detection mechanism 11, a CPU
l 2. Mode changeover switch 15. Motor Ml1 for driving the convergence lens group, reduction gear 14a, and coupling 1 for connecting to the automatic focus adjustment adapter 20
4b, a solenoid 16 for controlling the connection of the coupling 14b, and a solenoid drive circuit 17.

The automatic focus adjustment adapter 20b includes a conversion lens group, a lens drive system 2 that includes a coupling 21a that receives the output of a motor Ml in the body, and moves the conversion lens group in the optical axis direction, and a gear reduction system 21b.
1.

Furthermore, the automatic focus adjustment adapter 20b includes an optical system position detection means 22 for the conversion lens group and an in-adapter memory circuit 24 for storing the position detection signal of the conversion lens group by the optical system position detection means 22. There is.

Next, the operation of the third embodiment will be explained.

When the mode changeover switch 15 of the camera body IO is in the AF mode, the CPU 12 calculates the movement steepness of the conversion lens group necessary for focusing based on the detection signal of the focus detection mechanism 11, and according to the result, the CPU 12 operates the motor M1. to drive.

The output of the motor Ml is transmitted to the autofocus node A adapter 2o via the lens drive system 14, couplings 14b, 21a, and lens drive system 21 on the body side, and moves the conversion lens group in the optical axis direction. Perform focus adjustment.

If MF operation becomes necessary during AF operation, an MF interrupt occurs and the operation proceeds according to the flowchart of FIG.

When the mode selector switch 15 provided on the camera body 10 is set to MF mode in step 1, the step 2
In step 3, the CPU 12 determines the position of the conversion lens group based on the detection signal of the optical system position detection means 22 of the conversion lens group in the automatic focus adjustment adapter 20b, and in step 3, the CPU 12 controls the motor Ml in the automatic focus adjustment adapter 20b. Drive.

Step 2.3 is repeated until the detection signal of the optical system position detection means 22 indicates that the conversion lens group is at the infinite position, and when the conversion lens group reaches the infinite position, the motor M2 is driven in step 4. is stopped, the solenoid 16 is turned on in step 5, and the camera body 10 is turned on in step 6. Automatic focus adjustment adapter 20b
After the cup links 14b and 21a between the two are disengaged, the driving force is not transmitted to the autofocus adapter 20b, and the conversion lens group is fixed at the reference position.

Through the above operations, the autofocus adapter 20 becomes optically equivalent to a normal teleconverter, and the interchangeable lens 30 becomes optically equivalent to a normal teleconverter.
Ordinary focusing using the distance ring would be fi 100 million.

In the third embodiment, a mechanism using a solenoid was explained, but the mode changeover switch 15 is provided with one more position between AF and MF switching, that is, AF → (driving the conversion lens group) → MF, and the first Operation AF → (
In the second operation (driving the conversion lens group), the conversion lens group is driven to the infinite position without disconnecting the coupling, and the coupling 21a is connected at MF. The same effect as using a solenoid can be obtained even if a mechanism is used in which the switch is turned off and the MF is operated.

FIG. 7A and FIG. 8 show the fourth embodiment.

In this embodiment, the motor for driving the conversion lens group is built into the autofocus 2gIyH adapter 20c.

That is, the single autofocus adapter 20c includes a conversion lens group, a motor M2 for moving the conversion lens group in the optical axis direction, a lens drive system 26 on the adapter side, and the like.

Furthermore, inside the automatic focus adjustment adapter 20a, there is an optical system position detection means 22 for the conversion lens group, and a memory circuit 2 in the adapter that receives and stores a position detection signal of the conversion lens group from the optical system position detection means 22.
4.

Next, the operation of the fourth embodiment will be explained.

If mode selector switch 15 or AF mode, CPU1
2 calculates the movement -Y of the conversion lens group necessary for focusing based on the detection signal of the seven-point detection mechanism 11, and transmits the result to the motor drive circuit 25 of the automatic focusing adapter 20.

The motor drive circuit 25 drives the motor M according to instructions from the CPU 12.
The output of the motor M2 is transmitted by the lens drive system 26 on the body side, and the conversion lens group moves in the optical axis direction to adjust the focus.

If MF operation is required during AF operation, MF 71 is included and the operation proceeds according to the 813th flowchart.

When the mode switching switch 15 of the camera body 10 is set to MF mode in step l, the CPU l
2 determines the position of the conversion lens group based on the detection signal of the optical system position l detection means 22 of the conversion lens group in the automatic focus adjustment adapter 20c, and in step 3 the motor M2 in the automatic focus adjustment adapter 20a is activated. Drive.

Steps 2 and 3 are repeated until the detection signal of the optical system position detection means 22 indicates that the conversion lens group is at the infinite position, and when only the conversion lens group is at the infinite position, step 4 is performed and the motor M2 is driven or stopped. After that, the motor M2 is not driven and the conversion lens group is fixed at the reference position.

Through the following operations, the automatic focusing adapter 20 becomes optically equivalent to a normal teleconverter, and is capable of normal focusing using the distance ring of the interchangeable lens 30.

In addition, in the third and fourth embodiments, the optical system position detection means of the conversion lens group is sufficient to detect whether only the conversion lens group is at the infinity position, and the above-mentioned method is sufficient. The operation described and the operation with the turning effect are obtained.

Furthermore, even if there is no optical system position detection means, the relationship between the moving direction of the conversion lens group and the rotation direction of the motor is known, so when changing from AF mode to MF mode, the CPU moves the conversion lens group to infinity. If a command is given to the drive circuit to drive it in the far position direction and stop at the first limit hit, the conversion lens group will stop at the reference position, and if there is an optical system position detection means, the rotation effect will be improved. can get.

"Effects of the Invention" According to the automatic focus adjustment adapter according to the present invention, when the automatic focus adjustment adapter or the mode changeover switch provided on the camera body switches from AF mode to MF mode, the automatic focus adjustment adapter operates in conjunction with this switch, Since the conversion lens group or motor drives the 4Ii in the optical axis direction and sets it at the reference position, the autofocus adapter can be used as a normal teleconverter without any special operations, and the operability is extremely high. It is easy to use, and there is almost no risk of operational errors.

[Brief explanation of the drawing]

1 [A and 2 show the first embodiment of the present invention, FIG. 1 is a conceptual diagram showing the state in which an adapter is interposed between the camera body and the interchangeable lens, and FIG. 2 shows the operation. 3 and 4 show the second embodiment, FIG. 3 is a conceptual diagram showing a state in which an adapter is inserted between the camera body and the interchangeable lens, and FIG. Flowchart showing the operation, Figures 5 and 6 are as shown in Figure 3.
5 is a conceptual diagram showing a state in which an adapter is interposed between a camera body and an interchangeable lens, and FIG. 6 is a conceptual diagram showing an embodiment.
The figure shows a flowchart showing the operation, 7th LA and 8th vU show the fourth embodiment, FIG. 7 is a conceptual diagram showing a state in which an adapter is interposed between the camera body and the interchangeable lens, and FIG. 8 Flowchart showing the operation, No. 9
10 and 10 show a conventional example, in which No. 9 FA is a partial perspective view of the adapter partially cut away, and FIG. 10 is a perspective view showing the adapter and the interchangeable lens. 10...Camera body Ml...Motor 11.
...Focus detection mechanism 12...CPU13...Motor drive circuit 14...Lens drive system 14a...
Reducer 14b...Coupling 15...-
Mode changeover switch l 6-...Solenoid 17-
... Solenoid drive circuit 20-20c ... Auto focus 7A node adapter 21 ...
Lens drive system 21a... Color ring 21b.
・Gear reduction system 22 ・Optical system position detection means 23 ・Mode changeover switch 24 ・Memory circuit in the adapter ・Conversion lens group Ml ・Motor 7
' Go to ＼～ 笥1 Item 3 Figure q

Claims (1)

[Claims] 1. A conversion lens group interposed between a camera body and an interchangeable lens and movable in the optical axis direction, and a lens drive system that automatically drives the conversion lens group in response to a focus detection signal. an automatic focus adjustment adapter having at least a part of the adapter; a mode changeover switch that switches between autofocus mode and manual focus mode; 1. An automatic focus adjustment adapter for an interchangeable lens, comprising: a setting means for automatically positioning the lens in a certain position. 2. A conversion lens group interposed between the camera body and the interchangeable lens and movable in the optical axis direction, and at least a part of a lens drive system that automatically drives the conversion lens group in response to a focus detection signal. In the automatic focus adjustment adapter, the camera body is equipped with a mode changeover switch for switching between autofocus mode and manual mode, and when the mode changeover switch is operated to manual focus operation mode, the conversion lens group is set as a reference by the lens drive system. An automatic focus adjustment adapter for an interchangeable lens, characterized in that it is equipped with a setting means for automatically positioning the adapter in a certain position. 3. Claim 1 or claim 3, characterized in that a conversion lens group position detection means is provided, and a setting means is provided for automatically positioning the conversion lens group at a reference position based on a signal from the position detection means. Automatic focusing adapter for interchangeable lenses as described in item 2.