JPH02190834A - Camera - Google Patents

Abstract

PURPOSE:To surely perform the consecutive setting of magnification and focusing by performing an autofocusing action in a continuous autofocusing mode whenever photographing is performed with the aid of a variable focal lens. CONSTITUTION:Ordinary zooming photographing is performed by rotating a zooming operation ring 5 for performing variable magnification to an object in a certain distance and rotating a focusing operation ring 13 for correcting the movement of focus. However, in the case that an AF mode changeover switch is turned on to set the continuous AF mode, only the zooming operation ring 5 is rotated while slightly depressing a release button, so that zooming by autofocusing with the aid of a microcomputer muC is performed. Whenever photographing is performed with the aid of the variable focal lens, the autofocusing action in the continuous autofocusing mode is performed. Thus, a focusing state in accordance with the change of magnification is consecutively followed and focusing is surely performed.

Description

[Detailed Description of the Invention] The present invention moves a variable magnification lens group to continuously change the magnification of an object at a fixed distance, and focuses the object as it moves. The present invention relates to a camera capable of photographing using a varifocal lens that requires positional correction.

Conventional Technology Conventionally, for example, in a camera equipped with a zoom lens,
The autofocus operation can be switched between continuous autofocus mode, which continuously tracks the focus state as the variable magnification lens group moves, and single autofocus mode, which stops when focus is achieved. It can be switched arbitrarily.

However, when using a varifocal lens as a zoom lens, it is necessary to correct the focus position as the variable power lens group moves, which is difficult to do with conventional cameras. In some cases, people forget to change the switch, for example, and take variable-magnification shots while switching to single autofocus mode. I couldn't do it.

The present invention has been made in view of the above points, and an object of the present invention is to provide a camera in which autofocus operation is always performed in continuous autofocus mode when photographing using a varifocal lens. With the goal.

In order to achieve the above object, the present invention continuously changes the magnification of a subject at a fixed distance by mutually moving the variable power and focusing lens groups that make up the zoom lens. This is a camera that can be equipped with a varifocal lens, which requires the variable magnification lens group to be moved in order to change the magnification, and the focus position to be corrected as the lens moves. A switching means for switching autofocus operation between a continuous autofocus mode that continues tracking and a single autofocus mode that stops when an in-focus state is obtained;
A configuration comprising a setting means that sets the autofocus operation to an autofocus mode according to the switching state of the switching means, but sets it to a continuous autofocus mode when a varifocal lens is attached, regardless of the switching state of the switching means. That is.

According to this configuration, the setting means always performs autofocus operation in continuous autofocus mode when shooting with a varifocal lens, and continuously maintains the focus state according to changes in magnification. I will continue to pursue the target.

Friend" L Isamu A camera equipped with a zoom lens will be described below as an embodiment of the present invention with reference to the drawings.

First, FIG. 1 shows an example of a zoom lens used in this embodiment. The zoom lens consists of four components (groups) of positive, negative, positive and negative, and is capable of zooming from the wide side to the telephoto side for a subject at an infinite distance. If you have done 1. Second.
Third. 4th lens group (L+) (Lx) (Lff) (
t, 4) are moved as shown by solid lines in FIG. 1, respectively, to perform magnification change and focus movement correction. here,
The fourth lens group is designed to compensate for focal shifts during normal focusing and zooming. For example, when zooming from the wide-angle side to the telephoto side to always take pictures of a receding subject at a constant magnification, dβ camera body by a certain amount according to the photographing magnification from the in-focus position (A) for the subject, that is, the first
As shown by the thin line (B) in the figure, the focus movement correction is performed by moving toward the camera body.

Also, when zooming from the wide side to the telephoto side for a subject at a certain subject distance, the fourth lens group (L4) moves by d as shown by the dotted line (C) in Figure 1. At this time, the amount of movement d toward the camera body from the in-focus position for a subject at infinity changes in relation to the focal length f of the zoom lens between wide-telephoto settings. ing.

Next, a method for obtaining such a zoom lens will be described with reference to FIGS. 2(a) and 2(b).

First, Fig. 2(a) shows a zoom lens system with one convex lens at a certain focal length r, and the dashed dotted line indicates the state in which the subject is focused at infinity. For the subject, a defocus of ΔL will occur as shown by the solid line, and in D) f, ΔL=−f・β −・−・−1−−−・−
(1) becomes. Here, β is a lateral magnification and is a negative value because it is an inverted image.

Next, Fig. 2(b) shows the object at the shooting distance shown in Fig. 2(a) divided into a focusing lens group and a lens group closer to the subject, and fl is the first lens group. The focal length is the composite of the first to third lens groups in the figure, and f! is the focal length of the lens corresponding to the fourth lens group in FIG. Here, if the focusing lens group is moved toward the camera body by dβ in order to eliminate the defocus of ΔL and focus on the subject on the shooting path 1i1D, then let the magnification of the focusing lens group be β; , and its longitudinal magnification γ is expressed as follows, and from equation (1). Here, if fl1-β; is constant, by moving the focusing lens group from the in-focus position for the object at infinity by a certain amount according to the shooting magnification between wide and telephoto, the fixed magnification for the subject can be A zoom lens according to this embodiment is obtained, which achieves a focused state during imaging. That is, dβ=Cβ ・−−−〜・−・・・・
(5) (where C is a constant).

Here, β is a value determined from f and the position of the focusing lens group with respect to the film plane.

It is possible to determine the position of the focusing lens group so that f is a constant value. In addition, since the focusing lens group moves during focusing, 1
The value of −β; also changes, but there is no practical problem as long as the amount of movement is kept relatively small.

Since f is the combined focal length of f and f2, and fl is the combined focal length of the first to third lens groups in FIG. 1, after the position of each focusing lens group at f is determined, The first to
All that is required is to determine the position of the third lens group. Table 1 shows the numerical values of specific examples.

Here, e++et+es is L+-Lz, Lt at the paraxial
-L: I+ L 3 - Focusing refractive powers φhφ2. of the first to fourth lens groups at intervals of L 3 - La. φ3. φ4 is φ, =0
．． 0076, φ2--0.00865. φy=0
．． 0173. φi=−0.0168.

Above, a method for obtaining a zoom lens as shown in FIG. 1 was specifically explained using FIGS. 2(a) and 2(b), but the method is not limited to this. Similar calculations can be made in the case shown in FIG. 3 in which a lens group with a focal length r is added after the focusing lens group in (b). Here, equation (1) holds true in the same way, but the defocus of ΔL for a subject at a shooting distance must be multiplied by /βi, assuming that the vertical magnification γ of the additional lens group is β; , 1dβ of the movement of the focusing lens group to eliminate defocus and focus on ΔL is ΔL d p ” (1−β;)β; −−−−−−−−(
3') fβ = (1−βtatami βτ −−−−−−−(4°5,
Here, it is sufficient to configure fl(1-β;)β; to be constant. A zoom lens with such a configuration will further increase the degree of freedom in optical design when moving additional lens groups during zooming.
The degree of freedom may be increased by changing by zooming.

For example, Figure 4 shows the focusing lens group.
An example is shown in which the lens is configured with two groups, L4.
This is done by changing f2, which is the combined focal length of l and L4'', and by moving the normal focusing beam, angle, and'' all together, and Table 2 shows the specific values.

Here, el+e2+e3 is paraxial, -L,,L,
-Llit L φko, φ4 is φ, =0.013
5. φ, =-0,0679°φ, =0.0278.
φ, =0.0204.

Next, FIG. 5 shows the specific configuration of a camera equipped with a zoom lens as shown in FIG.
2) is a zoom lens unit that is detachably attached to the camera body (1), and (3) is a fixed barrel (4) of the zoom lens unit (2).
), and (5) is a zoom operation ring that is rotatably held relative to the fixed barrel (4).
5) passes through the circumferential groove (6) of the fixed cylinder (4) and attaches to the cam ring (
An interlocking lever (8) inserted into the straight groove (7) of 3) allows the cam ring (3) to rotate together with the cam ring (3) while allowing its straight movement. (9) is the guide bottle (10
) passes through the straight groove (11) of the fixed cylinder (4) and the cam ring (
The straight ring (9) is inserted into the circumferential groove (12) of 3), and the straight ring (9) is only allowed to move straight with respect to the fixed cylinder (4), and moves straight together with the cam ring (3). There is. (13
) is a focus operation ring rotatably held with respect to the fixed barrel (4), and the focus operation ring (13) moves straight so that the rotation of the ring causes the straight ring (9) to move straight in the optical axis direction. It is helicoidally bonded to ring (9). (Ll) (Lx) (L3) is its holding frame (14)
(15) (16) guide bin (17) (18) (
19) are the cams (20) and (21) of the fixed cylinder (4), respectively.
(22) and the first grooves (23) and (24) of the cam ring (3) for variable magnification. Second. In the third lens group,
Each lens group (Ll) CLt) (L3) is a cam ring (
3), when the cam ring (3) is rotated, it is moved as shown in Fig. 1 by the cams (20), (21), and (22). (L4) is a focusing and focus movement correction device in which the guide pin (26) of the holding frame (25) is inserted into the straight groove (27) of the fixed barrel (4) and the cam (28) of the cam ring (3). This lens group (L4) moves straight together with the cam ring (3) when it moves straight, and when the cam ring (3) rotates, it is moved by the cam (28) as shown in Figure 1. It is now being moved to . (29) is a magnification scale for constant magnification photography printed on the circumference of the focus operation ring (13), (30) is a magnification scale, a display window for viewing (29) from the outside, (31) ) is an autofocus (AP) coupler that transmits the driving force of a motor provided on the camera body (1) side to a focus operation ring (13) to perform focusing. Incidentally, FIG. 6 is an external view of the lens shown in FIG. 5.

Next, FIG. 7 is a block circuit diagram showing the circuit configuration of a camera having such a configuration, and (μC) is a microcomputer that performs calculations and sequence control for focus adjustment. (LEC) is a lens circuit provided within the zoom lens, which transmits information specific to the zoom lens to the microcomputer (μC). (AFC) is a focus detection circuit that photoelectrically converts the subject light that has passed through the lens and outputs focus detection data, which converts the focus detection data into a digital signal and outputs it to a microcomputer (μC).

(DSP) is a display circuit that displays the focus of the lens and indicates that focus cannot be detected. (M) is a motor for driving the fourth lens group of the zoom lens, and the lens drive circuit (
The lens drive circuit (LDC), which extends and retracts the fourth lens group under the control of the microcomputer (μC), receives a motor drive speed signal, a motor drive direction signal, and a motor stop control signal from a microcomputer (μC). is input, and based on this, the motor (M) is driven. (FE
NC) is a focus encoder that detects the amount of rotation of the motor (M) and outputs pulses to the microcomputer (μC) according to a predetermined amount of rotation of the motor (M).

Here, the microcomputer (μC) has a built-in lens position counter NL for determining the amount of movement of the fourth lens group from its infinity position as an absolute amount. This lens position counter NL is reset to NL=O by an internal command when the fourth lens group is at the infinity position, and when the fourth lens group is moved to the near distance side, the focus is set by an internal command. Encoder (FEN
C) is counted up in response to a pulse from the focus encoder (FENC), and when the fourth lens group is moved toward infinity, the count is counted down in response to a pulse from the focus encoder (FENC) by an internal command. When the fourth lens group is moved to the closest position, the lens position counter N
The value of L is NL=No.

This maximum movement IN, .

(BAT) is a power supply battery, and a microcomputer (
μC) and other circuits. Power battery (BA
A time constant circuit consisting of a series circuit of a resistor (R1) and a capacitor (cl) is connected to both ends of the resistor (T).
The connection point between R1) and the capacitor (C3) is connected to the power-on reset terminal (RES) of the microcomputer (IC). When the power supply battery (BAT) is connected, a power supply voltage is applied between the power terminal (Vcc) and the ground terminal (GND) of the microcomputer (μC), and the microcomputer (μC) becomes active, but the capacitor ( The microcomputer (μC) does not operate until the charging voltage of C1), that is, the voltage applied to the reset terminal (RES) of the microcomputer reaches a predetermined voltage. When the voltage of the capacitor (C5) exceeds a predetermined voltage, the microcomputer (μC) is reset and
Start a predetermined control operation.

(Sω) is an infinity position detection switch, which is turned on when the lens is retracted to the infinity position.

(S) is the main switch, and is turned off when using the camera.
N is given. (Sl) is a photographing preparation switch, which is normally turned on by the first stroke of a release button (not shown). (S,) is a release switch that is turned on by the second stroke of the release button, and when this release switch (S2) is turned on under certain conditions, a photograph is taken. (S□a) is the AF mode changeover switch.
> ON to enter continuous AF mode, OF
When set to F, it becomes single AF mode.

(ZENC) is a zoom encoder that sends a digital signal according to the rotation angle of the zoom operation ring (5) to the lens rotation l (
LEC). (S2) is a zoom switch that switches between normal zoom and constant magnification zoom, (RM) and (A
o) is R that stores unique information according to the state of the lens.
OM, zoom encoder (ZENC), zoom selector switch (S2), and lens circuit (LE) related to the read timing signal from the microcomputer (IC).
A signal from the processing circuit (?IC) in C) causes the ROM (
RM), both of which are provided in the lens circuit (LEC) along with the processing circuit (MC). Therefore, as described above, the lens circuit CLEC) outputs information specific to the lens depending on the states of the zoom operation ring (5) and the zoom changeover switch (s2), such as the focal length (f) and the lens extension amount conversion coefficient (K).
, a zoom request signal (ZOOM) (ZOOM=1 in normal zoom when the zoom changeover switch (s2) is OFF, ZOOM=0 in constant magnification zoom when it is ON), etc.

Next, the operation of the camera configured as described above will be explained.

First, in manual focus with the coupler disconnected, when the focus operation ring (13) is rotated, the cam ring (3) moves straight in the optical axis direction through the straight ring (9), and the fourth lens group (L4) 6 Next, the coupler is connected and the driving force from the motor (M) is transferred to the focus operation ring (13) through the coupler.
The rotation of the focus operation ring (13) causes the fourth lens group (L,) to similarly move in the optical axis direction for focusing. In this case, the moving direction and moving amount of the fourth lens ffL) are controlled by a microcomputer (μC).

Next, for constant magnification photography, first switch the zoom selector switch (S2) to rcONsT MAG J, rotate the focus operation ring (13) manually or by the motor (M), and set the desired setting on the magnification scale (29). Once the magnification is set, the fourth lens group (I4) will move from the in-focus position for an object at infinity to a fixed distance according to the set magnification.
It will be moved by β. Then, when the zoom operation ring (5) is rotated, the cam ring (3) is rotated through the interlocking lever (8), and the cam ring (3) is rotated from the first degree to the second degree. Third lens group (L,
)(LX) (I3) moves as shown by the solid line in Figure 1 for zooming, and the fourth lens group (I4) moves, for example, on the thin line (B) in Figure 1 for focusing. .

Then, when the focus is on the subject whose perspective has changed by rotating the zoom operation ring (5), press the release button lightly and first turn on the shooting preparation switch (Sl) to turn on the single AF mode (for example, switch the AF mode switch (SAF
When (a) is ON), after precise focusing is automatically performed by a microcomputer (μC), pressing the release button strongly and turning on the release switch (I2) will take a fixed magnification photograph.

In addition, in normal zoom shooting, the zoom operation ring (5) is rotated to change the magnification for a subject at a certain distance, and the focus operation ring (13) is rotated to correct the focal shift.
) is done by rotating.

However, if the AF mode selector switch (SA□) is turned on and the continuous AF mode is set, the zoom operation must be performed while lightly pressing the release button (that is, with the shooting preparation switch (Sl) turned on). ring (5)
By rotating the chisel, the microcomputer (μC
) Zooming will be performed using automatic focusing.

Next, the control operations of the microcomputer (μC) in each of the above operations will be explained with reference to the flowchart of FIG.

First, when the microcomputer (μC) is reset, it proceeds to step (Ill) and turns on the main switch (SN
) is turned on, and if it is turned on, the process proceeds to step (+12) to execute a subroutine for retracting the fourth lens group to the infinity position. Then, proceed to step (I3) and switch to the main switch (SN).
) is OFF, and if it is not OFF, proceed to step (+15) and turn on the lens circuit (LEC).
Load lens data from .

Then, in step (I6), the zoom request signal ZOOM is checked from the lens data, and if ZOOM=1, it is normal zoom, and in step (1110), continuous AF mode is selected regardless of the AF mode selector switch (SA□). If it is determined that ZOOM=O in step (116), it is determined that the zoom is at a constant magnification, and in step (117) it is determined whether the shooting preparation switch (S+) is turned on or not. Determine. If it is OFF, the process proceeds to step (I3) where it is again determined whether the main switch (SN) is OFF or not.
If it is FF, the fourth lens group is retracted to infinity in step (114) and the process returns to the first step (11). If it is determined in step (17) that it is ON, the process proceeds to step (+18) to determine the AF mode, that is, the AF
Determine whether the mode selection switch (SA, I4) is ON or not. If ON, go to step (110) for continuous AF mode; if OFF, go to step (I9)
After executing a subroutine for setting the single AF mode, the process proceeds to the next control flow.

Next, FIG. 9 is a flowchart that is a partial modification of the flowchart in FIG. 8, in which automatic focusing at the darkest point of normal zoom I is performed using a lens position counter without using a focus detection circuit (AFC). FIG. That is, the value of the lens position counter NL is the number of rotations of the coupler (31), that is, the value of the fourth lens group (I
Since the amount of movement of 4) (feeding out 31) is proportional to dβ, it is also proportional to the magnification β from equation (4), Nt= Aβ −−−−−(6) (However, A
is a constant). Here, now the focal length of the zoom lens.

The magnification when is β. At this time, the lens position counter NL
If the value of is No, then the focal pressure M r .

When the same object path t (1iD) changes to f, the magnification for focusing on 1iD is β. Therefore, at this time, the focus encoder (FE
If the number of pulses from NC) is N, then N--Aβ and No=
Aβ. By substituting equation (8) into this, we obtain the number of pulses necessary to focus at the new magnification, and drive the coupler until the value of the lens position counter NL reaches N. All you have to do is move the fourth lens group.

In terms of accuracy, such a method results in defocusing of ΔL based on Δβ, which is the error of β determined by equation (8), and can be expressed as ΔLζΔβ·f −·min−·− (11). Here, since the lens position counter Nt is a counter that is also used for AF control based on the focus detection circuit (AFC), it has sufficient resolution for defocusing. For example, when the resolution of the zoom encoder (ZENC) is f/f, = 2t4, from equation (8), β = β0 + Δβ = 2z4·β.・−・〜・・−(
12) is obtained, Δβ=(1-2”)β. ・−・−・−・−・(
13). Therefore, Δβ becomes maximum at 1β.

When is the maximum, let this be β, , = −0, 1, then Δ
βl ,,, =0.0029, and if the allowable defocus is 0.3 mm with ±0.15 width, f≦0°3=102II+m −−−−−− from equation (11).
...(14) 0.0029. Therefore, sufficient accuracy can be ensured up to a range of about 100 mm.

Next, the portions of the flowchart shown in FIG. 9 that are different from those shown in FIG. 8 will be explained. That is, step (116)
If it is determined that ZOOM=1, that is, normal zoom shooting, the process advances to step (1117) and the previous step (
Focal length information f from the lens data read in 115)
is taken out and stored in the memory in the microcomputer (μC) as fo.

Further, in step (118), the value of the lens position counter NL at that time is set as No and stored in the memory.

Then, in step (1119), the subroutine for reading lens data is executed again, and then in step (1119), the subroutine is executed to read the lens data again.
In step 120), fo stored in the memory is compared with the newly read focal length information f, that is, it is determined whether f=f.

If the zoom operation ring (5) is not operated during this time, it is determined that ff is reached and the process proceeds to step (I27), but if the zoom operation ring (5) is operated, the newly read focal power #f is rf=r.

It is determined that this is the case, and the process proceeds to step (121). That is, the value of No stored in the memory in step (1121) is (10)
As stated in the formula, f/f is multiplied by N for focusing at the new focal length. And step (12
It is determined in step (122) whether N obtained in step 1) is less than or equal to the maximum extension ilN, and if N≦N m a At step (1125), a subroutine for driving the lens is executed, and when they become equal, it is assumed that the lens is in focus, and at step (126) the lens is stopped, and at step (1125), the lens is driven.
Return to cloud 16). Also, in step (122) N>N,
, ll, N□ is reset to N in step (It24), and the process proceeds to step (123).

Next, FIG. 10 shows another embodiment in which the camera configuration example shown in FIG. 5 is partially modified.
) and focus operation ring (13), a zoom motor (M2) and focus morph (MP) are provided on the zoom lens side, and the driving force of the zoom motor (M2) is transmitted from the zoom gear ring (32) to the 1171st group (Ll). Holding frame (14)
The holding frame (14) rotates and moves in a straight line, thereby rotating the cam ring (3) and transmitting the signal to the other second frame (14). The third lens group (LZ) (L3) is also moved straight. Further, the driving force of the focus morph (MF) is transmitted from the focus gear ring (33) to the straight ring (9), and the cam ring (3
) causes the fourth lens group ( ) to move in a straight line. Note that (34) is a magnification scale for constant magnification photography printed on the circumferential surface of the focus gear ring (33), and (35) is a focal length scale printed on the circumferential surface of the zoom gear ring (32). . Incidentally, FIG. 11 is an external view of the lens shown in FIG. 10.

Therefore, the block circuit diagram of FIG. 7 was also modified as shown in FIG. 12 in accordance with the modification of FIG. A drive circuit fl (FDC) and a focus encoder (FENC) are connected, and a zoom motor (M2), its drive circuit (FDC), and a zoom encoder (ZENC) are also connected.

Then, with the zoom selector switch (S2) turned ON, turn the zoom switch (Syw) to the tele or wide side.
Normal zooming is performed by operating N, and the zoom switch (S2) is set to OFF with the zoom selector switch (S2)
Constant magnification zooming can be performed by turning tJ to the tele or wide side, and focusing can be performed by turning the focus switch C3rs) to the far or near side.

Next, the operation of the camera having such a configuration will be explained.

First, for manual focus, use the focus switch (S
When r++) is operated, the focus motor (MF) is rotated and the fourth lens group (shi) is moved in the optical axis direction for focusing.

At this time, the direction and amount of movement of the fourth lens group (L4) are controlled by the microcomputer (L-μC) (μC). f
When the camera is turned on, it becomes autofocus.

Next, the constant magnification is determined by first rotating the focus gear ring (33) by driving the focus motor (M) and setting the desired constant magnification on the magnification scale (34).
As described above, the lens group (L4) is moved by a certain amount according to its set magnification. Then, the zoom gear ring (32) is rotated by driving the zoom motor (M2) to focus on the subject whose perspective has changed.

In addition, in normal zoom shooting, the zoom motor (M) is rotated to change the magnification for a subject at a certain distance, and one focus mode (MF) is used to compensate for the focal shift.
This is done by following the rotation by a predetermined amount. Here, the rotation amount of the focus motor (M) is determined by the zoom encoder (ZENC) and focus encoder (FEN).
With the focal path Mf and magnification β based on the information from C),
It can be calculated by performing arithmetic processing to keep D=f/β constant. In other words, the lens-side microcomputer (L
-μC) has a built-in lens position counter N to know the amount of rotation of the zoom motor (M2), and this lens position counter Nt generates a pulse corresponding to the rate of change in focal length generated from the zoom encoder (ZENC). When the lens is driven toward the long focal length side, the count ups, and when the lens is driven toward the short focal length side, it counts down.

Note that the lens position counter N is the same as described above. Therefore, if you reset the value of the lens position counter N, when the focal focal length is f0, to Nf = 0, then the focal length is "
. The value of the lens position counter Nt when changes to f is: N, = B log"-7-; ---
−−−−−(15) (However, B is a constant) When substituting this into equation (10), N=No x
2' (However, when No is N, -0 is the lens position counter NL.
). Therefore, the lens position counter N, when f is (
All that is required is to drive the focus motor (MF) and move the fourth lens group until the focal length becomes N.

Furthermore, the accuracy of this method is F5.6 when B=40.
When calculated using the method described above for the depth of ±0.1hm,
This means that it can handle up to f = 200m-.

Next, such a microcomputer (L-μC) (μC
) will be explained with reference to the flowcharts of FIGS. 13 and 14. still,
The microcomputer (L-μC) on the lens side is configured to be completely controlled by the microcomputer (μC) on the main body side, so for the sake of explanation, we will consider both as one, and the parts related to communication between the two will be explained below. Omitted.

First, when the microcomputer is reset, the process proceeds to step (131) and the main switch (SN) is turned off.
It is determined whether or not it is turned on. If it is turned on, the process proceeds to step (1132) to execute a subroutine for retracting the fourth lens group to the infinity position. and,
Proceed to step (1133) and determine whether the main switch (island) is OFF. If it is not OFF, proceed to step (+135) and press the zoom switch (syw).
Determine whether or not is ON. If the zoom switch (Stw) is turned on to the tele or wide side, the step (
136), check the zoom request signal and set ZOOM=1.
If so, it is assumed that it is a normal zoom and a subroutine for zoom driving is executed in step (137), and if ZOOM=O, it is assumed that it is a constant magnification zoom and a subroutine for constant magnification driving is executed in step (138). In addition, in constant magnification mode, the status of the zoom switch (StJ) is checked.
The zoom motor (M2) is driven until it turns OFF. Then, in step (143), it is determined whether or not the release switch (S2) is turned on. If it is turned on, the process proceeds to step (1144) to control the fire after release; if it is turned off, step (133)
will return to. Also, in step (135), the zoom switch (syJ is set to the tele side).

In the case of OFF, which is not operated on any of the wide side,
Proceed to step (139) and focus switch (SF)
It is determined whether X) is turned on to the far or near side, and if it is turned on, a focus drive subroutine is executed in step (140), and if it is turned off, it is executed in step (141). Proceed to step (
140), the focus switch (
The state of S□) is checked, and the focus morph (MF) is driven until it becomes OFF. Then, in step (141), it is determined whether or not the photographing preparation switch (S+) is ON, and if it is OFF, step (1133
), and if it is ON, a distance measurement subroutine is executed in step (142), and after confirming focus, the process proceeds to step (+143) described above.

Next, FIG. 14 shows the flow for executing the zoom drive subroutine. First, in step (1151), the flag ZSTOP indicating that the zoom motor has been stopped is reset (ZSTOP = 0), and then in step (#52) )
Then, the value of the lens position counter NL at that time is read and stored in the memory. Then, after resetting the value of the lens position counter N in step (153), step (
154), the zoom motor (M2) is driven to the telephoto or wide-angle side. Then, in step (55), it is determined whether the zoom switch (syw) is OFF or not, and if it is ON, the process proceeds to step (158).
If it is OFF, in step (156) the zoom motor (M
2) and set the flag ZSTOP indicating that the zoom motor has been stopped at step (+157).
Proceed to step (158).

Then, in step (1158), the value N of the lens position counter Nt read from the memory is multiplied by 2B to obtain the value N of the lens position counter NL necessary to bring the lens into focus, and then in step (+159) again. Lens position counter N
Reset f. Then, whether the N obtained in step (158) is less than or equal to the maximum feeding amount NIIIX or the step (+
160), and if N > N-ax, step (
161), reset N and □ to N, and proceed to step (
1162), and if N≦N11. If so, immediately proceed to step (162) to determine whether the value of the lens position counter N, is equal to N, and if not, proceed to step (162).
After executing a subroutine for driving the fourth lens group in step 163), the process returns to step 1155. Further, if it is determined that the value of the lens position counter NL has reached N in step (162), it is assumed that the lens is in focus and step (+1
At step 64), the driving of the fourth lens group is stopped. Then, in step (165), it is determined whether a flag (ZSTOP) indicating that the zoom motor has been stopped is set, and if it is not set, it is determined that the zoom motor is being driven and the process returns to step (1155). However, if it is set, proceed to the next control flow.

As described above, according to the present invention, the autofocus operation is always performed in the continuous autofocus mode when photographing with a varifocal lens, so that the automatic focus operation is always performed in the continuous autofocus mode. Continuous magnification setting and accompanying focusing can be performed reliably.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the movement of a lens group in one embodiment of the present invention, FIG. 2 is a diagram for explaining the principle, and FIG. 3 is a diagram for explaining the principle of another embodiment. 4 is a diagram schematically showing the movement of the lens group in another embodiment, FIG. 5 is a diagram showing a specific example of the configuration of a camera equipped with the lens group shown in FIG. 1, and FIG. An external view of the lens section, FIG. 7 is a block circuit diagram showing its circuit configuration, FIG. 8 is a flowchart for explaining the control operation of the microcomputer, and FIG. 9 is a flowchart showing a modification of FIG. 8. , FIG. 10 is a diagram showing a modification of FIG. 5, FIG. 11 is an external view of the lens section, FIG. 12 is a block circuit diagram showing the circuit configuration, and FIG. 13 is a diagram showing the control operation of the microcomputer. FIG. 14 is a flowchart for explaining the zoom drive subroutine. (L,) (Lm) (L3) (L4) - 1st. Second. Third. 4th lens group. (5)-m-Zoom operation ring. (13) - 11 Focus Okasaku ring. (29L--Magnification scale section. (μC) (L-μC)--Microcomputer. (SA engineering)--AF mode selection switch. (Sz)--Zoom selection switch. (FENC)-- Focus encoder. (Zll!NC) ---Zoom encoder. (Mr) ---Focus motor. (h2) ---Zoom motor.

Claims (1)

[Claims] (1) By mutually moving the variable power and focusing lens groups that make up the zoom lens, the variable power lens group is moved in order to continuously change the magnification of a subject at a certain distance;
It is a camera that can be equipped with a varifocal lens that needs to correct the focus position as it moves, and it can provide a continuous autofocus mode that continuously tracks the focus state. a switching means for switching the autofocus operation between a single autofocus mode and a single autofocus mode in which the autofocus operation is stopped; A camera characterized in that it is provided with a setting means for setting a continuous autofocus mode regardless of the setting.