JPH02118540A - Automatic focusing camera - Google Patents

Abstract

PURPOSE:To improve focusing accuracy without reference to whether a subject is stationary or dynamic by providing a moving body decision means, and finding a defocusing quantity due to movement and correcting a focus detection result when the subject is in motion. CONSTITUTION:The focus state of a photographic lens as to the subject to be put in focus is detected by a focusing detecting means 1 and then its defocusing quantity is outputted. The moving body decision means 2 detects a variation speed from the defocusing quantity to decide whether or not the subject is dynamic. When the subject is dynamic, a tracing correcting means 3 finds the quantity of variation in defocusing and the means 1 corrects the defocusing detected by the means 1. A lens driving means 4 moves a lens for focus adjustment toward a focusing position according to the corrected value to put the subject in focus at the time of exposure. Consequently, the focusing accuracy of the dynamic subject is also increased as well as a stationary subject.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic focusing camera that drives a focusing lens toward an in-focus position according to focus detection results, and It is particularly suitable for cameras.

[Prior Art] In conventional automatic focusing cameras, the focusing accuracy when photographing a dynamic subject is lower than the focusing accuracy when photographing a still subject. This is because if the subject is moving, even if the lens is driven to the in-focus position at the time of the current focus detection and the shutter is released, the subject will shift from the in-focus position during the time lag until the shutter is released. Therefore, as disclosed in Japanese Patent Application Laid-Open No. 60214325,
When the subject is moving, it has been proposed to perform tracking correction in which the lens is driven in accordance with the speed of the subject.

On the other hand, it has been proposed to use a focus-waste priority mode in which release is permitted when the amount of defocus obtained by focus detection is smaller than a predetermined value.

By using this focus priority mode, necessary focusing accuracy can be ensured, and it is possible to prevent photographs that are significantly out of focus.

[Problems to be Solved by the Invention] However, in the focus priority mode, lens driving and focus detection are repeated until the subject enters the in-focus zone, so there is a problem that it is easy to miss a photo opportunity.

Therefore, if the focusing zone is set wide on the premise that the lens is driven for focus compensation during the release time lag, it is thought that it is possible to reduce the chances of shutter release inhibition and to make it difficult to miss a photo opportunity.

Furthermore, it is thought that the shift in focus during the release time lag for the above-mentioned dynamic subject can also be compensated for by driving the lens during the release time lag.

The present invention has been made in view of these points, and its purpose is to be able to improve focusing accuracy for both moving and stationary subjects, and to
Our goal is to provide an autofocus camera that makes it difficult to miss a photo opportunity.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, the first
As shown in the figure, in a camera in focus priority mode that has a release time lag, there is a focus detection means (1) that detects the amount of defocus of the photographing lens with respect to the subject to be focused on, and a focus detection means (1) that detects the amount of defocus of the photographing lens with respect to the subject to be focused on, and whether the subject is a dynamic subject or not. When the moving object determining means (2) determines that the subject is a moving object, the focus detecting means (1) calculates the amount of change in defocus due to the movement of the subject. Tracking correction means (
3), and a lens driving means (4) for driving a focusing lens toward a focus position based on the focus detection result by the focus detecting means (1), and the lens driving means (4)
) is characterized in that it operates at least during the release time lag.

Note that it is preferable that the tracking correction means (3) is a means for performing correction so that an in-focus state is achieved during exposure.

However, FIG. 1 is an explanatory diagram showing the configuration of the present invention in functional blocks, and in the embodiments described later, the main part of the above configuration is realized by a microcomputer program. To show a specific correspondence, the focus detection means (1) is #107 in FIG. At #113, the moving object determination means (2) transmits the tracking correction means (at #329 in FIG. 10).
3) corresponds to #401 to #417 in FIG. 12, and lens driving means (4) corresponds to #359 in FIG. 11, respectively.

[Action Co. Hereinafter, the operation of the present invention will be explained with reference to FIG.

The focus detection means (1) detects the focal point of the photographing lens with respect to the subject to be focused, and outputs the amount of defocus (defocus DFO>).
FO is a variable whose sign indicates the direction of defocus and whose absolute value indicates the magnitude of defocus.

The moving object determining means (2) determines whether the subject is a moving subject, for example, by detecting the rate of change of the defocus DFO. When it is determined that the subject is a dynamic subject, the amount of change ΔDF in the amount of defocus due to the movement of the subject is determined by the tracking correction means (3), and the defocus DFO detected by the focus detection means (1) is corrected. Find the defocused MDF. This tracking correction means (3) can improve the focusing accuracy for a dynamic subject by performing correction so that the object is in focus during exposure. The lens drive means (4) is a defocus DFO detected by the focus detection means (1) or a tracking correction means (3).
Based on the defocus MDF corrected by , the focusing lens is driven toward the in-focus position. Since this lens driving means (4) operates at least during the release time lag, the time required to drive the lens can be shortened by an amount equivalent to the release time lag.

[Example] Embodiments of the present invention will be described below based on the drawings.

Fig. 2 shows a single-lens reflex camera with interchangeable lenses, where 101 is a camera body, 102 is a zoom lens, which is an example of an interchangeable lens (photographing lens), and 103 is a main mirror, with a reflecting section. and a transparent part. The light that has passed through the photographic lens is reflected by the reflection section of the main mirror 103 and guided to the finder optical system (not shown), and a portion of the light is transmitted through the sub-mirror 1.
You will be guided to 04. The sub mirror 104 is the main mirror 10
3 is reflected to the focus detection module 105. FIG. 3 shows the camera body 101 viewed from the front. As mentioned above, 101 is a camera body, 103 is a main mirror, 105 is a focus detection module, and 106 is a mechanical unit configured to automatically perform mirror up, exposure operation, film winding, and rewinding. Since these are not directly related to the present invention, their explanation will be omitted.

FIG. 4 shows a circuit diagram of a camera to which the present invention is applied. Reference numeral 201 is a camera control microcomputer that performs functions such as sequence control of the entire camera, exposure calculation control, and autofocus (hereinafter abbreviated as AF) calculation control, and has a data bus and various input/outputs as shown below. It includes terminals P1 to P21, etc. 202 is an AF distance measuring unit that measures the amount of defocus of a subject image, and includes a one-dimensional self-scanning image sensor (hereinafter abbreviated as CCD), a COD drive unit, an A/D conversion unit, and a reference power source for A/D conversion. Consists of sources etc. Image information obtained by this CCD is taken into the CPU 201 via the AF data bus 201a. 203 is a display unit consisting of a liquid crystal display (LCD) or a light emitting diode (LED), and the CPU 20
The display unit 203 displays information such as the shutter speed Tv and aperture value Ay, which are the calculation results of automatic exposure (hereinafter abbreviated as AE) sent from 1, or information such as in-focus/out-of-focus or shooting mode. 204 each interchangeable lens 10
This is a lens data circuit that is provided in the camera body 101, etc., and stores the maximum aperture value, the minimum aperture value, the focal length, and the extension amount conversion coefficient necessary for focus adjustment. The data is transmitted to the camera body 10 via an electrical contact provided near the mounting part.
1. 205 is a photometry unit that measures the brightness By of the subject, and includes a photoelectric conversion element for light reception, an A/D conversion unit, and an A/D conversion unit.
It is composed of a reference voltage source for /D conversion, a data exchange unit with the CPU 201, etc., and measures the light that has passed through the photographic lens according to a command from the CPU 201. A film sensitivity reading section 206 automatically reads the sensitivity of the loaded film, and the film sensitivity on the film cartridge is read through an electrical contact provided in the cartridge chamber of the camera.

The display section 203, lens data circuit 204, photometry section 2
05, each piece of information from the film sensitivity reading section 206 is input as a serial signal to the serial input/output section 201c (abbreviated as serial r10 in the figure) via the serial data bus 201b. Reference numeral 207 is a sequence motor M4 for winding and rewinding the film, an AF momo-M2 for driving the lens for AP, and a driver control unit for exciting various magnets required during exposure operation, and an output terminal of the CPU 201. It is controlled by control output lines CMDO to CMD8 from P8 to P16. SW1~SW
3. SW5-5W10 are switches, one end of which is grounded, and the other end connected to input terminals P1-P7, P2O, and P21, respectively. SWI is a switch that turns ON when film charging starts and turns OFF when film charging is completed. SW2 is a switch that turns ON while the mirror is up and turns OFF when mechanical charging is completed. SW3 is a switch that repeats ON10FF multiple times while the film is running. be. SW5 is a photometry switch that is turned on at the first step of pressing down a shutter button (not shown), and the CPU 201 outputs a signal to start photometry and distance measurement. While this switch SW5 is ON,
If the lens is in an out-of-focus position due to distance measurement, the lens continues to be driven, and when it reaches the in-focus position, the lens stops driving, but the shutter button is released while the lens is being driven and the switch SW5 is turned OFF. If so, stop driving the lens. SW
Reference numeral 6 denotes a release switch that is turned on in the second step of pressing down the shutter button, and when this switch SW6 is turned on when the release is possible, the CPU 201 issues a command for the release operation. In addition, the release switch SW
6 is turned on, the photometry switch SW5 is configured to be kept in the on state. SW7 is a film detection switch provided in the film travel path. When there is film at this film detection switch SW7, the switch SW7 is OFF, and when the film runs out, it is ON. When rewinding, This switch S
When W7 changes from OFF to ON, it indicates that the film is slightly out of the cartridge, and is used as a switch for determining the end of rewinding. SW8
is a cartridge detection switch installed near the electrical contact of the film sensitivity reading section 206 installed in the cartridge chamber of the camera, and is turned on when a cartridge is in the cartridge chamber and the back cover is closed; If there is no patrone, it will be in the OFF state. SW9 is a back cover opening/closing switch, which is turned ON when the back cover is completely closed. 5WIO is a multiple exposure mode selection switch, and O
When set to N, the mode becomes multiple exposure mode.

RESET is set to control power supply voltage +Voo by resistor R1.
This is a reset terminal that is pulled up to 1. After the power is turned on, the capacitor C1 is charged via the resistor R1, and when the voltage changes from the "Lou+n level" to the "High" level, the CPU 201 is reset. X is a crystal oscillator for providing a clock signal to the CPU 201.

Next, the driver control section 207 and each control section will be explained. ICMg is a magnet for holding the first shutter curtain, and when the control output line ICMGO becomes "Low" level, the magnet ICMg is energized and the first shutter curtain is held. 20Mg is a magnet for holding the second shutter curtain, and when the control output line 2CMGO becomes Low level, the magnet 2CMH is energized to hold the second shutter curtain, and after releasing the holding of the first shutter curtain, The time during which the holding of the curtain shutter is released corresponds to the shutter speed. FMg is a magnet for locking the aperture of the photographing lens, and when the control output line FMGo reaches the Lot++" level, the magnet FM
g is energized to hold the aperture locking member, and when the holding is released, the aperture locking member operates to lock the aperture in a predetermined position. RMg is a magnet for release, and when the control output line R and MGO are at "Low" level for a certain period of time,
The release member is unlocked, the aperture is narrowed down, and the mirror is raised.

Q1 to QIO are sequence motor M and AF motor M
This is the second driving transistor. This sequence motor M has two types of coils inside, and can obtain the characteristics of high-torque, low-speed rotation and low-torque, high-speed rotation.It is possible to switch between both characteristics, and can rotate in forward and reverse directions. Transistors Q1 to Q6 are connected as shown in FIG.

That is, the high-speed terminal H of the sequence motor M+ is connected to the common connection point of transistors Q1 and Q2, the low-speed side terminal is connected to the common connection point of transistors Q3 and Q4, and the remaining common terminal C is connected to the common connection point of transistors Q5 and Q6. are connected to each. Table 1 shows how the rotational state of the sequence motor M1 changes depending on the on/off states of the transistors Q1 to Q6.

Table 1 Note that in this embodiment, the high-speed brake is not used, and only the low-speed brake is used. Therefore, in the following explanation, the term "brake" refers to the low-speed brake SBH. Q7 to QIO are transistors for driving the AF motor M2, and are connected in a bridge configuration so that the AF motor M2 can rotate in forward and reverse directions. The forward rotation of the AF motor M2 advances the lens, and the reverse rotation retracts the lens. OMI~
0M10 is a control output line for switching each transistor Q1 to QIO.

211 and 212 are an aperture encoder and an AP encoder made of photocouplers, and input signal lines PTI and PT
2 is connected to the driver control unit 207. The aperture encoder 211 monitors the stroke of the aperture preset lever at the time of release, and the light emitted by the light emitting diode 211a is detected by the phototransistor 211b at the time of release, and is input to the driver control unit 207 via the input signal line PTI. After the waveform is shaped into a pulse by this driver control unit 207, the input terminal P1 of the CPU 20 is passed through the output signal line FP.
Sent on 8th. The AF encoder 212 is for monitoring the rotation speed of the AF motor M2 for driving the lens during AF, that is, the amount of movement of the lens.
2b, and is input to the driver control unit 207 via the input signal line PT2. After being waveform-shaped into a pulse by this driver control unit 207, it is passed through the output signal line AFP to the input terminal P19 of the CPU 201.
will be sent to. This output signal line AFP is connected to the CPU20]1
It is also connected to an internal counter 201d and is used to monitor the extended position of the photographic lens. That is, the counter 201d is cleared to O at the end of the lens (1), and by setting it to count up when driving in the near direction and count down when driving in the ω direction, the number of pulses delivered from the ω end of the lens can be determined at any time. Obtainable. This AFP signal is also connected to an interrupt terminal (not shown) of the CPU 20, and an interrupt is generated at the falling edge of the AFP signal. In addition, the CPU 201 uses a timer 2016
It is configured so that the time can be read by counting the internal clock. moreover,
The CPU 201 can electrically write and read data,
So-called E2, which retains memory contents even when the power is turned off
Built-in PROM201f. Also, CPU201
is equipped with an interrupt timer (not shown) that generates a timer interrupt when a set time has elapsed.

CMDO to CMD8 are control output lines output from output terminals P8 to P16 of the CPU 201 to control the driver control unit 207, and CMDO and CMDI are control output lines R for controlling magnets RMg and FMg, respectively.
Control MGO, FMGO, CMD2. CMD3 controls control output lines ICMGO and 2CMGO for controlling magnets lcMg and 2CMg, respectively. Also, CMD
4 to CMD6 control the control output lines ○M1 to OM6 for Z-ken smoke M and driving, and CMD7. Control output line OM7 to 0Ml for driving AF Momo-M2 by CMD8
Controls 0. Table 2 shows the control of the sequence motor M1, and Table 3 shows the control of the AF motor M2. In the table, H is "
"High" level, L means °'Low level.

Table 2 In the table, H is "high" level for L means "Loud" level.

(Margin below) Table 3 In the table, H is “High” level L means "'L our" level.

AMg is a lock release magnet that holds the film still, and transistors Q11. CPU2 via resistor R2
01 output terminal P17. Transistor Ql
The connection point between the base of 1 and the resistor R2 is grounded via the resistor R3. The output terminal P17 of the CPU 201 is normally "'
Since the transistor Qll is in the OFF state, the magnet AMg is not energized and holds the attraction piece by attraction.In order to release the engagement between the winding stop and the winding stop lever, Output terminal P of CPU20i
When 17 becomes “High” level, the magnet AMg
is energized and the suction force is lost.

Next, a series of release operations in this embodiment will be explained with reference to FIG. As shown in the figure, the release operation is roughly divided into four sequences: mirror up, exposure, mechanical charge, and film charge.

In the mirror-up sequence, the main mirror and sub-mirror are retracted, and the aperture of the photographic lens is released to narrow the aperture.In the exposure sequence, the first and second curtains of the focal brain shutter are controlled. The exposure time (shutter speed) is controlled by In the mechanical charging sequence, the main mirror, sub-mirror, aperture of the photographing lens, and the first and second curtains of the shutter are energized by springs for the next release.

In the film charge sequence, the film is advanced.

This will be explained in more detail below using a time chart. As already explained in FIG. 4, the switch SW6 is turned on by pressing down the shutter button two steps to start the release operation. When the release operation is started, first, the control output line RMGO is set to Low level to energize the release magnet RMg and release the main mirror biased by the spring. , the main mirror is retracted to the finder side, and the sub-mirror is also retracted in conjunction with the main mirror.Next, by setting the control output line FMGO to the LoII+'' level, the magnet FMH for locking the aperture is energized. , releases the diaphragm of the photographic lens which is biased by a spring. When the lock is released, the aperture starts to be stopped. As explained in FIG.
The signal is multiplied by P and input to the CPU 201 . CPU201
counts the number of FP times the signal corresponding to the aperture value based on a predetermined exposure calculation, sets the control output line FMGO to the 'High' level, stops the aperture, and sets the photographic lens to the desired aperture value. Next, in order to perform the exposure operation, one of the control output lines ICMGO, which is at the "Low" level at the start of release, is set to the "High" level.This causes the focal brain shutter to The first curtain of the focal brain shutter runs.By setting the other control output line 2CMGO to the "High" level after the exposure time according to the predetermined exposure calculation has elapsed, the second curtain of the focal brain shutter runs,
Exposure control is performed. After exposure, a mechanical charge sequence begins. In the mechanical charging sequence, first, high torque is required when starting the sequence motor M1, so the sequence motor M1 is driven in low speed mode F(L), and then, when the predetermined rotation speed is reached, high speed mode F(L) with low torque and high speed rotation is performed. H). This allows efficient sequence motor MI
In addition to being able to drive a high-speed mechanical charge,
Film charge can be achieved.

This rotation of the sequence motor M1 causes the main mirror and submirror to move down and are biased by the spring, and at the same time, the aperture of the photographic lens and the first and second curtains of the focal plane shutter are also biased by the spring. When this mechanical charging is completed, as already explained, the switch SW2 is turned off as a mechanical charging completion signal. CPU
When the switch 201 detects that the switch SW2 is turned off, it shifts to the film charging sequence. This releases the lock that fixes the film and starts winding the film. At this point, the switch SW1 for monitoring the film charge is turned on, and the sequence motor M winds up the film. When film winding for one frame is completed, switch SW1 is turned to O.
It becomes an FF and is notified to the CPU 201. CPU201
- detects that the switch SWI is OFF, and applies a brake (not shown) to stop the sequence motor M. This completes the release operation for one frame.

Next, the sequence in the snapshot mode in which the camera is released continuously while the switch SW6 is ON will be described with reference to the time chart of FIG. 6, including the focus detection operation. Section I in Figure 6 indicates the first frame of quick shooting, and section ■ indicates the second frame of continuous shooting.
Showing eyes. Section I of the first frame of the quick shot is as explained in FIG. By the way, in order to perform focus detection, it is necessary that the main mirror and sub-mirror are lowered and stabilized. Therefore, the switch SW2 is turned OFF, and after the mechanical charging is completed and a period of time for mirror stabilization is waited, CCD integration is started. This waiting time is set to 30 m5ec in this embodiment. 1 in the diagram
The part indicated by 1 is the integration time of COD, and the part indicated by Dl is C
It shows the data dump time during which OD pixel data is A/D converted and taken into the memory of the CPU 201. CCD
When the pixel data is taken into the CPU 201, reliability of defocus, defocus direction, and focus detection is determined by predetermined calculations. Regarding this focus detection calculation,
Since it is not directly related to the present invention, the explanation will be omitted. Now,
When the first film charge is completed, switch SW
I is turned off, and the low speed brake SBR is applied to the sequence motor M.

At this point, the CPU 201 determines whether the switch SW6 is ON. If the switch SW6 is ON and the camera is in the snapshot mode, then the release of the second frame, which is indicated by section 3, is started. In the case of this second frame, to release the film immediately after charging the film, in order to ensure that the film stops, wait for a while with the low speed brake SBR applied to the sequence motor Ml, and press the release magnet RM.
.

is energized. Now, if the result obtained in calculation 1 is that the camera is in focus, you can take an in-focus photo even if you release the camera next time with the photographic lens stopped, but if it is not in focus, you can continue to release the camera next time. For example, out-of-focus photos may be taken. In particular, when shooting in continuous shooting mode, there are many cases where the subject is moving and the defocus changes over time, so in calculation 1, the defocus due to the movement of the subject is Detect minutes. By performing this defocus drive while the mirror is up, it is possible to obtain an in-focus photograph even at the next release. AF in Figure 6
The column for motor M2 shows the driving state of the photographing lens by the AF motor M2, and a single line indicates that it is in the OFF state and that the AFM section is being driven in either direction. To compensate for the defocus amount obtained as a result of calculation 1 or for the movement of the subject, the photographing lens is driven during mirror up in the next section H. Furthermore, when the control output line RMGO is at the 'Lou+' level, that is, when the release magnet RMg is energized, the A
The power supply to F motor M2 is turned off. This is because the current flowing through the release magnet RMg is very large, and if the AF motor M2 is driven during this time, the
This is to avoid problems such as the driving accuracy of the F motor M2 being degraded or the current flowing through the release magnet RMg being reduced, which may cause the mirror to become unlatched and not be able to be raised.

Thereafter, similarly to the first frame, the release is continued while the switch SW6 is ON.

Next, the operation of this embodiment will be explained using the flowcharts from FIG. 7 onwards. FIG. 7 is a flowchart when the photometry switch SW5 mentioned above is turned on. When the switch SW5 is OFF, the camera is in a low power consumption mode, a so-called sleeve mode. When the switch SW5 is turned on, clock oscillation starts and is activated. C
When the PU 201 is started, it sends a start signal and a clock to the peripheral IC in #101, and performs start-up processing such as initializing the boat.Subsequently, in #102, flags, constants, etc. used in the program are initialized. do, followed by #
At 103, switches in each part of the camera body are checked, and serial communication is performed with the flash, lens, display element, etc. Furthermore, in order to discharge unnecessary charges from the CCD, which is a focus detection element, initialization is performed at #104.

Proceed to the next step, focus detection processing CD I NTA (#105 onwards). First, prior to the integration of COD, #10
In step 6, the integration start time is input to the memory TMI of the CPU 201 from the timer and saved.

Similarly, the counter indicating the lens position mentioned above is read and saved in the memory T1. Then, in #1°7, the COD is integrated to obtain a signal level appropriate for focus detection. When the CCD integration is completed, the timer value is stored in the memory TM2 and the counter is stored in the memory T2 in #108. Save the value. Next, in #109, save the value of the memory TM in the memory TML, and save the value of the memory TM in the memory TM (7M2
−TMl)/2. TMI and 7M2 indicate the integration start and end times, respectively, and (7M2-TMI
)/2 means the time at the center of the term. That is, #10
9, the previous integration center time is saved in the memory TML, and the current integration center time is saved in the memory TM. Similarly, regarding the counter value, the memory MIL is set at #110.
Save the value of memory MI to memory MI (T2
- Save Tl)/2. As mentioned above, since the counter value corresponds to the lens position, Tl and T2 indicate the lens position at the start and end of integration, respectively, and (T2-TI
)/2 indicates the lens position at the center of integration. That is, in #110, the previous lens position of the center of integration is saved in MIL, and the lens position of the current center of integration is saved in MI.

Next, in #111, each pixel data of the CCD is sent to the CPU2.
Dump data to be input to 01. Using this COD pixel data, before starting the focus detection calculation, the value of the memory FO is saved in the memory LDF in #112. At this point, focus detection by CCD integration in #107 has not been performed, so the process in #112 saves the previously detected defocus DFO in the memory LDF. In #113, #107
A focus detection calculation is performed based on the COD pixel data integrated in , and the defocus DFO and defocus direction of the photographing lens as well as the reliability of focus detection are calculated. continue,
Serial communication and exposure calculation are performed in #114, display of photometric value, sensing of each switch, etc.0 For example, if switch SW5 is turned OFF between #107 and #114, it is detected in #114. The display is turned off, the motor is turned off, etc., and the state returns to the sleeve state. When the serial communication and exposure calculation are completed, the process proceeds to #115, where it is determined based on the flag VLYF whether or not a snapshot is currently being taken. This continuous shooting flag VLYF is set to 1 when the photographer has selected the quick shooting mode during the winding operation, which will be explained later. If the continuous shooting flag VLYF is 1 in the determination in #115, the flow branches to the quick shooting AF (#301). The flowchart of the quick-shooting AF will be explained in detail later using FIG. 10.

If the continuous shooting flag VLYF is 0, the process proceeds to #116, where it is determined whether or not the camera is in focus. In this focus determination, if the reliability of the focus detection in #113 is higher than a predetermined value and the defocus DFO is smaller than a predetermined amount, it is determined that the focus is in focus. In this case, the predetermined amount is 100
It is set to μ request. Also, this value is 60 μm + 8
You may also set it as Here, FNO is the F number of the aperture value.

Moreover, this predetermined amount is the E'P of the CPU 201 explained earlier.
It is written in ROM20 If. by this,
Users who desire high precision can write small values, while those who desire feel and focusing time can write large values, making it possible to respond to users in detail.

If focus is determined in #116, proceed to #117,
After one in-focus display, exposure recalculation and serial communication are performed. This is done in order to reflect the focus detection result in the exposure calculation. Thereafter, the process waits while performing serial communication in #120 until the ON state of the switch SW6 is detected in #11.

If it is determined in #116 that the focus is not in focus, #121
The process proceeds to the subsequent out-of-focus processing 0UTFS.

First, in #122, the focus display is turned off, and then in #123, as a result of the focus detection calculation, if it is determined that the focus detection result is unusable due to low reliability, that is, it is determined that the focus detection result is low, the AF motor M2 is not driven. In order to perform the next focus detection,
The process branches to focus detection processing CDINTA after #105. If the contrast is not low, proceed to #124 to start driving the AF motor M2, wait until the drive is finished in #125, and then proceed to focus detection processing CDINTA from #105 onwards in order to perform the next focus detection. . In #124, the conversion coefficient K obtained from the photographing lens is applied to the defocus DFO.
Multiply by L to obtain the number of driving pulses E of the AF motor M2 mentioned above.
Calculate RRCNT.

In other words, the number of driving pulses ERRCNT is ERRCNT=
Determined by DFOXKL. At #125, the AF motor M2 is driven until the AFP signal for monitoring the rotation of the AF motor M2 is detected for the number of drive pulses ERRCNT. Note that this conversion coefficient KL varies depending on the focal length of each photographing lens, and is sent from the photographing lens through serial communication. After that, #1 again from #105
The same process is repeated until focus is determined in step 16.

Next, a description will be given of the processing after the ON of the switch SW6 is detected in #119. In #126, it is determined whether the drive pulse number ERRCNT is smaller than the constant NPI written in the E2PROM 201f (#126). The number of driving pulses ERRCNT is a constant NP
If the number is greater than I, a constant N is added to the drive pulse number ERRCNT.
Please reset the PI #127), drive pulse number ERRCN
If T is smaller than the constant NPI, continue as #12
Proceed to 8. In #128, the defocus DFO determined in focus in #116 is a constant DFC! It is determined whether it is smaller than . If DFO<DFCl, the process branches to release (#131) to immediately perform a release operation. If DFO≧DFC1, proceed to #129,
It is determined whether the number of drive pulses ERRCNT is smaller than 4 pulses. If the drive pulse number ERRCNT is smaller than 4 pulses, the process immediately branches to release (#131). If the number of driving pulses ERRCNT is 4 or more pulses in #129, driving of the AF motor M2 is started in #130. In the processes from #126 to #131, it is determined whether or not to drive the photographing lens during mirror up.

As already explained, in #116, focus determination is performed based on whether the detected defocus is within a predetermined defocus range. If this focusing range is made very small, accuracy will increase, but it will take time to focus due to variations in focus detection, camera shake by the photographer, etc. Alternatively, problems such as small hunting of the photographic lens may occur. Furthermore, when the subject is a moving object, the detected defocus changes moment by moment, so no focus determination is made. For this reason, this focusing range is set to be wide enough to absorb variations in focus detection or changes in defocus due to changes in the subject. However, in this case, the defocus amount corresponding to the focusing range remains as an error. Therefore, this remaining defocus amount is driven while the mirror is up, thereby realizing an autofocus camera with even higher accuracy. Also, in order to shorten the time until release, the number of pulses that can be driven during mirror up is limited to a constant NPI #126. #127), if sufficient accuracy is ensured, that is, in #128 DFO<D
In the case of FCI, or if the number of drive pulses ERRCNT is smaller than 4 in #129, the AF motor M2
The drive accuracy of the camera is also taken into consideration, and the shutter is released immediately.

Next, a series of release controls (from #201 onwards) including mirror up, exposure time control, mechanical charging, and film winding will be explained using FIG. First, #2
At 02, set the flag RMGON F 4: 1 to indicate that the release magnet (RMg) is energized.
#203 TE A F Mo9 Turn off the power to M2
L, #204 energizes the release magnet RMg, the shutter curtain holding magnet)-ICMg, and 2CMg. After that, after waiting time in #205, energize the release magnet RMg in #206, ○FFL, #
At step 207, the flag RMGONF is cleared to O. this#
Through the processes from 204 to #206, the main mirror sub-mirror is unlocked and mirror-up is started. Also,
Through the processes of #202, #203, and #207, the AF motor M2 is prohibited from being energized while the magnet RMg is being energized. Specifically, the AF motor M2 is controlled by a timer interrupt that occurs every predetermined time.
When the flag RMGONF is 1, turning on the AF motor M2 and braking are both prohibited, and the AF motor M2 is turned off.

When the flag RMGONF is reset, the drive of the AF motor M2 is automatically restarted by a timer interrupt. This is done in order to prevent the inconvenience that by energizing M2, the current flowing through the magnet RMg becomes insufficient and the lock cannot be released and the mirror cannot be raised.

When the mirror up is started, then in #209, the aperture locking magnet FMg is energized.

As a result, the diaphragm of the photographic lens is unlocked and the aperture of the photographic lens is started. In #210, the pulses of the aperture encoder 211 described above are counted, and when the pulses set by the exposure calculation are calculated, the magnet FMH is de-energized in #211 to fix the aperture. Thereafter, in #212, the process waits for a predetermined time t1 to elapse from energization of the release magnet RMg, and then proceeds to #213. In #213, in order to prevent the photographic lens from being driven during exposure, the AF motor M2 is turned off to 0F.
FL, then turn off sequence motor M+ with #214
Make it. As already explained, the sequence motor M,
In the case of the second and subsequent frames of quick shooting, the brake is applied until it is turned off in #214.

Magnet ICM for holding shutter 1 curtain in #215
By turning off the power to g, the first curtain of the focal plane shutter runs, waits for the shutter speed at #216, and then starts shutter 2 at #217.
Turn off the electricity to the curtain holding magnet 2CMH and run the second curtain of the focal plane shutter. This completes the exposure. In #218, the timer value is saved in the memory TIME1. In #219, in order to wait for the second curtain of the focal plane shutter to complete its travel, wait for a predetermined time tl11 to elapse;
The process moves to the winding routine (#220).

In the winding routine shown in FIG. 9, first, at #221, the sequence motor M is energized in low speed mode, and at #2
After waiting for a predetermined time until the rotational speed of the motor M increases in step #22, the high speed mode is energized in step #223. As a result, the mechanical charging progresses, and the process waits until the switch SW2, which is the mechanical charging completion signal, is turned OFF in #224.

When the switch SW2 is turned OFF and the mechanical charge sequence is completed, the main mirror and sub-mirror are down, so TTL photometry becomes possible and photometry is started at #225. In order to proceed to the film charge sequence, as described above, the stop release magnet (AMg) for stopping the film is energized for a predetermined time t6 (#226).

After that, for a predetermined time t. The process waits for a period of time (#227), and then moves to #228. This predetermined time tlo is set to 3 Q m5ec in this embodiment, and is a waiting time for stabilizing the submirror. In #228, it is determined whether the continuous shooting mode is selected by the photographer, and if it is the quick shooting mode, the continuous shooting flag VLYF, which indicates that continuous shooting is in progress, is set to 1 in #229. After setting, the process proceeds to focus detection processing CDINTA after #105 in order to perform focus detection next time (#230). On the other hand, if it is not the continuous shooting mode, the process waits in #231 until the switch SW6 is turned off, and then proceeds to focus detection processing CD INTA from #105 onwards.

The automatic focus adjustment operation during continuous shooting will be explained using the flowchart in FIG. #1 from #230 in Figure 9
After proceeding to the focus detection process CDINTA from 05 onwards, focus detection calculation and exposure calculation are performed as explained in FIG. 7, and the process branches to continuous shooting AF (#301) at #115. First, at #3.2, exposure calculation and serial communication based on the photometric values started at #225 in FIG. 9 are performed.

This makes it possible to always obtain appropriate exposure even if the subject brightness changes during continuous shooting. Subsequently, in #303, the process waits until the switch SWI is turned off. That is,
Focus detection during film charging is limited to one time. This is to give priority to the next release since this is a quick shooting mode.

When the OFF state of the switch SWI is detected, the film charging sequence is completed, and therefore the sequence motor M is immediately braked at #3o4. In #306, it is determined whether the time required to wind the film is longer than a predetermined time. Film winding time varies greatly depending on the tension of the film, power supply conditions, number of frames, etc. If it is determined in #3.6 that the film winding is slow, then in #307 the following mode flag TF and the first time following flag Tl5TF are reset. The following mode flag TF will be explained later, but when the subject is a moving object, it is set in the following mode to correct the movement of the subject. If it is determined in #306 that the film roll-up is slow, the interval between snapshots is long and an error occurs in the correction for subject movement, so the tracking mode flag TF is reset.

In #308, it is determined whether the focus detection result is low contrast. If the contrast is not low, the process branches to #309 and the previous ignore flag LIF is reset. This previous ignore flag LIF is set when the next release is performed while ignoring low contrast during continuous shooting. Next, in #310, VHO is stored in VHI as the previous defocus speed (velocity at the image plane of the subject), and in #313, the current defocus speed WH is stored.
Find O.

The calculation of the defocus speed VHO in #313 is performed as follows. At the time of #313, the current focus detection result is stored as a defocus DFO. The previous focus detection result is saved in the memory LDF by the process #112 in FIG. Also, the lens position at the center of integration of the CCD that obtained the defocused DFO is:
Through the process #110 in FIG. 7, the lens position at the center of integration of the CCD at which the previous defocus LDF was calculated is saved in the memory MIL. As a result, the defocus change δDF caused by the movement of the subject is: δDF=DFO-LDF-(MI-MIL)/KL・
...■ is calculated. DFO-LDF is the change in defocus, and (M I - M I L)/K L is the defocus due to the movement of the lens during that time. On the other hand, the time Δt required during that time can be determined by subtracting the previous integration center time from the current integration center time.

From the process #109 in Figure 7, Δt=TM-TML...■
From equations 0 and 2, which are calculated as follows, the object speed VHO is calculated as VHO=δDF/At.

After determining the subject speed VHO in #313, the process proceeds to #319. On the other hand, if it is determined that the contrast is low in #308, the process proceeds to #311. In #311, it is determined whether the previous ignore flag LIF is 1 or 0. If it is cleared to 0, the process proceeds to #312, where the previous ignore flag LIF is set and the current detection defocus DFO is set to 0, Set the drive pulse number ERRCNT to 0. #31
1, if the previous ignore flag LIF is set to 1, it branches to the cancellation routine ○UTR■2 in #314, and in #315, the following mode flag TF is set, and the following initial flag Tl5TF, which will be explained later. Reset + respectively,
After clearing the continuous shooting flag VLYF in #317, the 7th
Jump to #121 0UTFS in the diagram (#318
), If low contrast is detected twice in a row during focus detection during continuous shooting by the processing from #308 to #318, the quick shooting mode is canceled, the release operation is prohibited, and the 7th According to the flowchart explained in the figure, release is prohibited until focus is achieved.

As a result, in the case of a moving subject, even if the subject moves out of the focus frame during quick shooting or a subject with no contrast enters the picture, it is possible to take the picture at least once, reducing the probability of missing a so-called dramatic moment. is significantly reduced. Furthermore, the probability of significant defocusing is low. In particular, in quick-shooting mode, the photographer often wants to prioritize the release, and the effect is great.
If low contrast is detected twice in a row,
Since continuous shooting is interrupted until the camera is in focus again, the release will not continue with a large amount of defocus, and if the photographer is careless and takes continuous shots of an unintended subject, or if the photographer puts his or her hand in front of the shooting lens. #312 does not waste film even in cases where it is covered with
The number of drive pulses ERRCNT is undefined. Therefore, each of these is set to 0. Furthermore, since the defocus speed VHO cannot be calculated, it is not updated.

That is, the previously detected defocus speed VHO is used. Subsequently, in #319, it is determined whether the current tracking mode is selected. If the tracking mode flag TF has been reset and it is not the tracking mode, the process advances to #320 and the defocus speed VHO determined in #313 is
and constant ■E1, and if VHO>VEI (7), constant FZR is set to INFZ which is the focusing range in #321.
ELI is set, and when VHO≦■E1, a constant FZREL2 is set in #322. FZRELL is F
It is set narrower than ZREL2. In other words, when the defocus speed VHO is small, the subject is stationary, and in this case, the defocus change due to subject movement is small, so a wide focusing range is set, and when the defocus speed VHO is large, the subject is stationary. , since the defocus change is large, set a narrow focusing range. As a result, when the subject is stationary, there is less need to drive the photographic lens, and stable and fast continuous shooting is possible. By using a narrow focusing range, the camera achieved high-precision snapshots with little tracking lag. Also, these constants v
E1, FZRELI, and FZREL2 are written in E"PR, 0M201f in the CPU 20i, and can be rewritten according to the photographer's preference. In #323, #3
21, the focusing range INFZ set in #322 is compared with the currently detected defocus DFO. If the defocus DFO is smaller than the focusing range INFZ, it is determined that the accuracy is sufficiently high, the process proceeds to #370, and the switch SW6 is
It is determined whether or not is ON. If the switch SW6 is ON, the next release is requested by the photographer, and the next release is jumped (#371), that is,
Since accuracy is ensured, the next release is possible without having to drive while the mirror is up. Switch SW6 is O
If it is FF, the process branches to release processing 0UTRV after #372, and the continuous shooting flag VLYF is set in #373 and #374.
After resetting the initial tracking flag Tl5TF, in order to perform the next focus detection, focus detection processing CDI from #105 onward is performed.
Jump to NTA (#375).

On the other hand, in the judgment of #323, the currently detected defocus DFO
If the value is greater than or equal to the focusing range INFZ, the process advances to #324 to determine whether the photographic lens is driven or in tracking mode. In #324, it is determined whether the subject brightness is bright or dark. Specifically, the determination is made based on the COD integration time and the gain multiplied by the output data, and if it is dark, the process branches to #333. If it is bright, the process proceeds to #325 and calculates the image magnification β of the subject. In #326, it is determined whether the image magnification β' is larger than the constant BETALOCK. If β>BETALOCK, #3
It branches to 33. If β≦BETALOCK,
Proceed to #327, defocus speed VHO is constant RV
Determine whether it is greater than MIN. VHO≦RV
If MIN, branch to #333 and VHO>RVM
In the case of IN, the process proceeds to #328, where the defocusing speed VHO is compared with the constant RVMAX.

VHO-11! If RVMAX, the process branches to #333, and if VHO<RVMAX, the process branches to #329.

In #329, it is determined whether the current and previous defocusing speeds VHO and VHI obtained in #310 and #313 are in the same direction or in opposite directions, and if they are in opposite directions, the process branches to #336. , #33 if in the same direction
In #330, it is determined whether the follow-up initial flag Tl5TF is set to 1, and if it is cleared to 0, it branches to #335 and is set to 1.
If it is already set to 1, the tracking mode flag TF is set to 1 in #331, and the tracking processing routine RN is executed.
Jump to AFTI.

Through the processes from #323 to #332 described above, a tracking mode for correcting the change in defocus due to the movement of the subject is determined. That is, if it is determined in #324 that the subject is dark, it takes time to integrate the COD and the noise component is large, so the defocus speed VHO cannot be determined accurately, and the tracking mode cannot be entered. Also, #3
If it is determined in step 26 that the image magnification is large, the tracking mode cannot be entered in the same way because the influence of camera shake of the photographer is large. #327 defocus speed■HO is constant R
If the value is below VMIN, it is not possible to determine whether the defocus change is caused by variations in focus detection or by the movement of the subject, and in order to avoid incorrect correction, the tracking mode cannot be entered. Even if the defocus changes, the speed is slow, so the defocus changes are small and can be ignored without correction.

If it is determined in #328 that VHO≧RVMAX,
The change in defocus is abnormally large and cannot be considered to be a movement of the subject; it is determined that the subject has changed, that is, the camera has been shaken, and the tracking mode cannot be entered. If the directions of the previous and current defocus speeds VHI and VHO are reversed in #329, it is thought that the focus detection is unstable or the subject is moving irregularly, and there is a high possibility that incorrect correction will be made. I can't enter it. Furthermore, #330, #331, #33
By performing the process 5, the tracking mode is entered when the determination conditions #323 to #329 are passed twice in succession. This makes it possible to reliably determine whether or not the subject is a moving object, and there is no risk of erroneous correction. Also, the constant BETAL
OCK, RVMIN, and RVMAX are written in E2PROM201f built in CPU2016
If the direction of the defocus speed VHO is reversed in #329, particularly unstable focus detection or subject movement is expected, so proceed to the cancellation process 0UTRV3 after #336, and set the tracking mode flag in #337. TF, the initial tracking flag Tl5TF, and the continuous shooting flag VLYF are reset, and the process jumps to focus detection processing CDINTA from #105 onward to perform the next focus detection (#338). As a result, the next release is prohibited, and as explained in FIG. 7, the lens is driven until the lens is brought into focus again, so there is no need to worry about out-of-focus photography being performed.

If it is determined in #324, #326, #327, #328, and #330 that the process branches to #333, the currently detected defocus DFO is compared with the constant INFZEl. When DFO<INFZEI, the defocus is not very large and the reliability of focus detection is high, and sufficient accuracy is ensured even if the taking lens is driven by this amount of defocus while the mirror is up and the next release is performed. Therefore, the process branches to the drive routine RNMTR during mirror up. D
In the case of FO≧INFZE1, the defocus is large and if you release the lens next time as it is, there is a possibility that accuracy cannot be ensured. Therefore, perform the cancellation processing 0UTRV2 hegejump (#334), #333, and #334. When the defocus is small, highly accurate automatic focusing and high-speed continuous shooting can be achieved by driving the mirror up while the defocus is large, and when the defocus is large, the transformation point is detected and focused. Automatic focusing is achieved.

In addition, if the defocusing process 0UTFS is entered after the cancellation process 0UTRV2 from #334, as explained in FIG. It is fast and accurate. Also, the constant INFZEI is the E2PR of CPU201.
It is written in the OM201f and can be changed according to the user's preference.

Now, the follow-up process RNAFTI executed by branching based on the determination in #319 or jumping from #332 will be explained with reference to FIG. First, in #340,
Determine whether the directions of the current and previous defocus speeds VHO and VHI are the same. If the directions are different, it is possible that the subject suddenly stopped, changed direction, or shook the camera. Possible, in this case #3
41, jumps to cancellation processing 0UTRV3, cancels the tracking mode, and performs automatic focusing operation until focus is achieved again. This allows highly accurate focusing without making erroneous corrections even when the subject suddenly stops, changes direction, or shakes the camera.

If they are in the same direction, proceed to #342 and (VH
Compare O+VH1)/2 with the constant AVESH. (VH
O+VH1)/2 indicates the following from the process of #310, and becomes a weighted average value. In the above equation, n is the number of loops, and V Hi indicates the speed of the ith previous loop.

That is, in #342, the weighted average value and the constant AVESH are compared. If the weighted average value is less than or equal to the constant AVESH, the weighted average value is reset to the defocus speed VHO in #343, and if it is greater than the constant AVESH, the process directly proceeds to #344. In other words, in the case of low speeds, by performing weighted averaging, stable correction is achieved that absorbs variations in focus detection, etc., and in the case of subjects approaching at constant speed, the change in defocus is approximately equal to the distance. It increases in inverse proportion to the square of the square, and as a result, at high speeds, correction with good responsiveness and little follow-up delay is achieved. In addition, the constant AVES) I is B"FROM built in the CPU 201.
201f.

In #344, calculate the image magnification β and use the constant BETALOC
Compare with K2. As the image magnification increases, the influence of camera shake increases as described above, so the canceling process 0UTRV2 hejump is performed in #347, and the tracking mode is also exited. In addition, the constant BETALOCK2 is the E2PR of the CPU 201.
It is written in OM201f, and the constant BETALOC
It is set larger than K. #345 compares the defocus speed VHO with the constant RVOUT, and if the defocus speed VHO is within RVOUT, the defocus speed is sufficiently slow, and #347 Branch to. In #346, the defocus speed VHO and constant RVMAX2 are compared. If the defocusing speed VHO is equal to or higher than RVMAX2, it is determined that the defocusing speed is very fast and that even if follow-up correction is performed, the delay will be large and defocusing will occur, and the process branches to #347. In #347, release processing OUTR
Jumps to V2, cancels tracking mode, prohibits the release next time and performs focus detection again. This prevents the release in the case of a very fast subject and prevents the camera from taking photos that are delayed in tracking. . The processes of #344 to #346 prevent erroneous correction and achieve highly accurate correction.

Subsequently, follow-up correction calculation 1 is performed in #348 to calculate the number of drive pulses ERRCNT. This calculation will be explained in detail later using FIG. 12. In #349, the defocus MDF after tracking correction is compared with the constant INFZE2. If the defocus after tracking correction is large, the process branches to #350 and jumps to the cancellation process 0UTRV2 after #316 (FIG. 10) in order to improve accuracy. As a result, only the continuous shooting flag VLYF is cleared, the tracking mode is maintained, and the out-of-focus processing is shifted to 0UTFS. Constant INFZE2 is E2PRO of CPtJ201
It is written in M201f. Also, this constant INF
ZE2 is set larger than the constant INFZEl explained in #333. This is because tracking correction is performed, and unless the correction amount is large, the process cannot proceed to #351.

The steps after #351 are mirror-up drive processing, and #33
This is the branch from #3 or the flow from #349. First, in #352, it is determined whether the switch SW6 is ON. If the switch SW6 is OFF, the next release is not requested, so the process branches to #363 and the release process 0
Jump to UTRV. Subsequently, in #353, the number of driving pulses ERRCNT and the constant NPI are compared. As explained in FIG. 7, the constant NP1 is the number of pulses that can be driven during mirror up. If the number of driving pulses ERRCNT is less than or equal to the constant NPI, driving is possible during mirror up, and the process branches to #359.

If the number of driving pulses ERRCNT exceeds the constant NPI, driving cannot be performed only during mirror up, and therefore a driving time is required before the next release starts. Also, this A
The time required to drive the F motor M2 varies depending on power supply conditions, characteristics of the interchangeable lens, etc. For this reason, if the time until the next release start is fixed at 40 m5ec, and the number of drive pulses ERRCNT is 40 m5ec and the number of pulses that can be driven during the next mirror up (within constant NP2>), A
Drive the F motor M2 and increase the number of drive pulses ERRCNT.
If the value exceeds the constant NP2, refocus detection is performed. As a result, tracking correction can be performed accurately for 40 m5ec even in the moving object mode. Furthermore, even if the camera waits for 40 m5ec, the speed of snapshots will only drop from 3 frames per second to 2.7 frames per second, and the deterioration of the feel of the snapshots will be minimal. Furthermore, when the number of driving pulses ERRCNT exceeds the constant NP2, 5 refocusing detections are performed, which solves the problem that the error associated with lens driving increases indefinitely.

If ERRCNT≦NPI in #353, the process advances to #354 and the tracking flag TF is determined. If it is tracking mode (TF=1) in #354, tracking correction calculation 2 for 40 m5ec is performed in #355, and if TF=0, #355 is skipped, and in both cases, the number of drive pulses ERRC is set in #356.
Compare NT with constant NP2. Drive pulse number ERRCN
If T exceeds the constant NP2, the process branches to #364 and jumps to release processing O[JTRV2. #349, #
In the determination of step 356, if the next release is to be performed by driving during mirror up without performing focus detection again, it is determined that the camera is in focus, and the in-focus display is maintained. Next, A at #357
Start driving F motor M2 and drive 40m5ec at #358
Wait for an amount of time. In #359, the drive of AF motor M2 is started in case it branches from #353, and in #36
The process advances to the quick-shooting release process RNRELESE after 0.

Since continuous shooting is performed in #361, in order to completely stop the film, the camera waits for a predetermined time tll, and then jumps to the next release. As is clear from the above explanation, in the tracking mode, it is necessary to correct the defocus change caused by the subject, so the next release is not performed while the photographing lens remains stopped.

Next, the follow-up correction calculations after #401 will be explained with reference to FIG. First, in #402, it is determined whether or not the current focus detection was low contrast. If it was not low contrast, the correction time T is determined in #403.

The time of the integration center of this COD is saved in the memory TM, and if you subtract the value in the memory TM from the current timer value TC and add the mirror up time of 7Q m5ec, from the current integration center to the next exposure. Find the time. In the case of low contrast, the process proceeds to #404 to find the time T from the previous exposure time to the next exposure time. As explained in FIG. 8, the previous exposure time is saved in the memory TIME1. Therefore, it is sufficient to subtract the value of the memory TIME 1 from the current timer value TC and add 7Q m5ec. That is, #402
~#404, if the contrast is not low, calculation is performed based on the current defocus DFO, and if low contrast, calculation is performed assuming that the defocus was 0 during the previous exposure.

Next, in #4o5, set the defocus speed VHO to the above #
Multiply by the time T obtained in step 403 or #404 to obtain the correction amount ΔD
Next, in #406, the defocus speed VHO and the constant VVH are compared. If VHO>VVH and the defocus speed is fast, it is determined in #407 whether the subject is approaching or going away, and if the subject is approaching, the correction amount ΔDF is multiplied by 1.25 (#408).
As mentioned above, if the subject approaches in the optical axis direction at a constant speed, the defocusing speed will increase in inverse proportion to the square of the subject distance.
The defocusing speed also increases during the time T determined in step 3 or #404. In order to correct this error, the correction amount ΔDF is multiplied by 1.25. When the subject is far away, the defocus speed becomes slower, so the correction amount Δ
Multiply DF by 0.75 (#409). Next, #410
This time detected defocus DFO and defocus speed VH
Check the direction of O, and if the direction is the same, the corrected defocus MDF will be DFO + ΔDF (#411)
, if the direction is different, the currently detected defocus DFO is compared with the correction amount ΔDF in #412, and DFO≦ΔDF is determined.
If so, set ΔDF-DFO in the correction defocus MDF (#413). If DFO>ΔDF, the photographing lens must be driven in the opposite direction to the defocus speed direction, and the defocus This means that a large defocus is detected in the direction opposite to the speed direction. Therefore, assuming a backlash error due to reversal of the photographic lens or abnormal movement of the subject, the stack is initialized in #414, and the next release is prohibited by proceeding to release processing 0UTRV21 in #415. When the corrected defocus MDF is determined in #411 and #413 where refocusing is detected, the process multiplies the defocus by a coefficient KL for converting the defocus into the number of pulses in #416, sets the number of driving pulses ERRCNT, and returns (#416). 417).

This allows for highly accurate correction even when the subject is moving at high speed, and can also be used for subjects that are approaching or moving away. Furthermore, as is clear from the explanation of FIG.
Even when the low contrast is ignored once in #308 to #312, the moving bones of the subject are corrected correctly.

Finally, timer interrupts and AFP interrupts will be explained.

FIG. 13 shows a timer interrupt processing routine for driving AF Momo-M2. The CPU 201 has a built-in interrupt timer (not shown) that generates a timer interrupt when a set time has elapsed. When a timer interrupt occurs, #5
In step 02, the interrupt timer IT is reset, so that the interrupt timer IT automatically generates a timer interrupt when the set time elapses after the current timer interrupt occurs.

Next, the flag RMGONF is determined in #503, and if it is set, the release magnet RMg is being energized, so the AF MOMO-M2 is turned OFF as described above (#505), and the flag RMGONF is set. If it has been reset, energize AF Momo-M2 in #504,
Return (#506).

FIG. 14 shows an AFP interrupt processing routine that occurs at the falling edge of the AFP signal. When an AFP interrupt occurs, first, in #602, the number of drive pulses ERRCNT is decreased by one. In #603, the number of drive pulses ERRCNT becomes O, and it is determined whether or not the drive of the AF momo-M2 has ended. The number of driving pulses ERRCNT is not 0, and the AF momo-M
If the drive in step 2 is not completed, proceed to #604,
In #605, the interrupt timer IT is reset, and the flag RMGONF is checked. Flag RMGONF
is set and the release magnet RMg is energized, turn AF MOMO-M2 off with #608.
Make it F. If the flag RMGONF has been reset, the brake is applied to AF Momo-M2 in #606 and the process returns (#607);
If the driving of Momo-M2 has been completed, the process branches to #609, and in #609, the power supply to AF Momo-M2 is turned off.

Next, timer interrupts are made at #610 and #611, respectively.
Disable AFP interrupt and return (#607).As described above, AF Momo-M2 is driven by the timer interrupt and AFP interrupt, and while the release magnet RMg is energized, AF Momo-M2 is Controlled to OFF.

[Effects of the Invention] As described above, in the automatic focusing camera of the present invention, the lens is driven during the release time lag, so for a stationary subject, the focus compensation due to this lens drive is The focusing zone can be widened, reducing the chances of the shutter release being inhibited in focus priority mode, making it harder to miss a photo opportunity, and
When the subject is a dynamic subject, the focus detection result is corrected by calculating the amount of focus shift due to the movement of the subject, and the lens is driven during the release time lag based on the corrected focus detection result. This has the effect of being able to compensate for out-of-focus due to movement of the subject.

Note that tracking correction for a dynamic subject can improve the focusing accuracy for a dynamic subject by correcting the focus detection result so that it is in focus during exposure.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a side view of a camera as an embodiment of the present invention, FIG. 3 is a front view of the same as the above, and FIG. 4 is a block circuit diagram of the same as the above. 5 and 6 are operation waveform diagrams of the same as above, and FIGS. 7 to 14 are flow charts showing the same operation as above. (1) is a focus detection means, (2) is a moving object determination means, (3)
(4) is a tracking correction means, and (4) is a lens driving means. Figure 1

Claims (2)

[Claims] (1) In a focus priority mode camera having a release time lag, a focus detection means for detecting the amount of defocus of a photographing lens with respect to a subject to be focused;
a moving object determining means for determining whether or not the subject is a moving subject; and a focus detecting means for determining the amount of change in defocus due to movement of the subject when the moving object determining means determines that the subject is a moving subject. tracking correction means for correcting a focus detection result by the focus detection means; and a lens drive means for driving a focus adjustment lens toward a focus position based on the focus detection result by the focus detection means, the lens drive means at least An autofocus camera that operates during a time lag. (2) The automatic focusing camera according to claim 1, wherein the tracking correction means is a means for performing correction so that a focused state is achieved during exposure.