JPH043535B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an autofocus camera with a built-in strobe that performs two-point zone focusing, and more specifically, the present invention relates to an autofocus camera with a built-in strobe that performs two-point zone focusing. This invention relates to an autofocus camera with a built-in strobe that is improved so that the lens set position for positioning the lens can be changed depending on the situation. Many cameras with built-in distance measuring devices and strobes are already on the market, and recently, in order to lower prices, the lens can be set at only two positions, a near-field position and a far-field position, to improve the field of view. A two-point zone focus type is also known, which uses depth to obtain a clear image. In this conventional autofocus camera with a built-in strobe, distance measurement and lens setting are performed in the same way as for daytime photography when photographing with a strobe. In general, in the case of strobe photography, it is known from experience that close-up photography is often required because the photographing distance is restricted in relation to the amount of light emitted. However, in the past, the lens setting position was determined mainly for daytime photography, which often involved long-distance photography.
The problem with strobe photography was that the image was easily blurred. Furthermore, in the case of flash photography, since the aperture is opened, the depth of field becomes shallow, which also has a large effect on the blurring of the image. SUMMARY OF THE INVENTION An object of the present invention is to provide an autofocus camera with a built-in strobe that can obtain clear images in both daytime photography and strobe photography. The present invention is characterized in that the boundary for distinguishing between the near zone and the far zone is changed in strobe photography and daytime photography, and the lens set position is also changed. Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a camera embodying the invention. On the front of the camera body 1, there is a lens section 2,
A strobe light emitting section 3, a light projecting section 4 that emits near-infrared light, light receiving sections 5 and 6 that receive the near-infrared light reflected by the subject and returned, a focuser 7, and a release button 8 are provided. . The lens section 2 is
It is composed of a movable lens barrel 10 that holds a photographing lens 9, and a fixed lens barrel 11 that slidably accommodates the movable lens barrel 10. The strobe light emitting unit 3 is activated when the strobe switch 12 is set to the ON position. Note that the strobe light emitting section 3 may be popped up when the strobe switch 12 is set to the ON position. Furthermore, the brightness of the subject may be measured, and the strobe may automatically emit light when the brightness is lower than a predetermined brightness value. FIG. 2 shows the lens setting mechanism.
In the movable lens barrel 10, the lock lever 15 is connected to the spring 1.
6, and rotates counterclockwise around the shaft 17, and when released from the locking portion 18, moves rearward due to the stored force of the spring 19. This lock lever 1
A permanent magnet 20 is fixed to 5, and is normally attracted to an electromagnet 21. When the electromagnet 21 is energized, a force acts between the permanent magnets 21, causing the lock lever 15 to rotate counterclockwise. The approximately L-shaped positioning lever 23 controls the amount of movement of the movable lens barrel 10 by receiving one of the shoulders of the stepped teeth 24 formed on the movable lens barrel 10 at one end thereof. This positioning lever 23 is rotatably supported by a shaft 25 and biased to a neutral position by a spring 26. Also, a bar magnet 2 is attached to the positioning lever 23.
7 is fixed, and one magnetic pole is connected to the coil 2.
8 into the notch 30 of the iron core 29 which is magnetized. Note that numerals 31 and 32 are pins for receiving the spring 26. When the electromagnet 21 is not energized, the movable lens barrel 1
Since the lens 0 remains locked by the lock lever 15, the photographing distance is 1.35 m in the case of an f40 mm photographic lens, for example. When a forward current flows through the coil 28, the iron core 2
9 is magnetized to the south pole, the positioning lever 23 rotates clockwise about the shaft 25. When the electromagnet 21 is energized at the same time or after a delay using a delay circuit, the lock lever 15 is released from its attraction and rotated counterclockwise against the spring 16. This lock lever 15 is
Since the locking of the movable lens barrel 10 is released, the movable lens barrel 10 is moved backward by the stored force of the spring 19, and the stepped teeth 24 are moved back.
It collides with the first shoulder of the vehicle and stops. At this time,
The photographic lens 9 focuses at a distance of 1.5 m. When only the electromagnet 21 is energized without the coil 28 being energized, the movable barrel 10 is moved back to a position where the positioning lever 23 collides with the second shoulder of the step tooth 24 . At this time, the photographic lens 9 is 2m
The focus is on the distance. When a current flows in the opposite direction to the coil 28, the iron core 2
Since the end 29b of 9 is magnetized to the S pole, the positioning lever 23 rotates counterclockwise. Electromagnet 2
1 is energized, the movable lens barrel 10 starts to retreat and stops at the position where the positioning lever 23 collides with the third shoulder of the step tooth 24. In this case,
The photographic lens 9 focuses at a distance of 4 m. The movable lens barrel 10 is returned to the position where it is locked by the lock lever 16 by a winding operation, and is moved between two points by the electromagnet 21 and the coil 28, one for daytime photography and one for flash photography. Two points are set at four points in total. A diaphragm plate 35 having an aperture 35a is arranged behind the movable lens barrel 10, and when the diaphragm plate 35 enters the optical axis L, the aperture becomes F4.6, and when the aperture plate 35 retreats from the optical axis L, the aperture opens to F2, for example. .8. Behind this aperture plate 35, a shutter 36 and a film 37 are sequentially arranged as is well known. FIG. 3 shows the drive mechanism of the aperture plate.
The aperture plate 35 has a substantially L-shape, is supported by a shaft 39, and is biased by a spring 40 in a direction in which a permanent magnet 41 is attracted to an electromagnet 42. When the electromagnet 42 is not energized, the permanent magnet 41 and the electromagnet 42 are attracted to each other, so that the aperture plate 35 is located on the optical axis L. When the electromagnet 42 is energized, the aperture plate 35 rotates clockwise against the spring 40, so the aperture plate 35 retreats from the optical axis L and becomes an open aperture. FIG. 4 shows the electrical configuration of the present invention. The distance measuring device 45 includes a near-infrared light emitting diode 4
6 and a lens 47, the light emitting unit 4 and the light receiving element 4
8 and a lens 49, and a light receiving section 6 including a light receiving element 50 and a lens 51. The drive circuit 52 causes the near-infrared light emitting diode 46 to emit light for a certain period of time in response to the ranging start signal.
After this light emission ends, a distance measurement end signal of "H" is output. The light receiving unit 5 is for detecting the subject distance zone during daytime photography, and looks at the distance measurement zone from 1.2 m to 2.2 m, which is the shortest shooting distance of the photographic lens 9, and detects the subject in this area. exists, the near-infrared light emitted from the light projector 4 and reflected by the subject is received. Therefore, when the light receiving section 5 receives the reflected light, the object is present in the short distance zone up to 2.2 m. If no reflected light is received, it is determined that the subject exists in the long distance zone. The light receiving unit 6 is for detecting the subject distance zone during strobe photography, and is 1.2 m to 1.6 m.
I am looking at the distance measurement zone of m, and the subject is 1.6 m.
Determine whether it exists in the nearer zone. The output signals of the light receiving sections 5 and 6 are transmitted through amplifiers 54,
After being amplified by 55, comparators 56 and 57
and is compared with a reference voltage set by a voltage divider made up of resistors 58 and 59. The output signals of the comparators 56 and 57 are connected to a latch circuit 60, which is reset when the release button 8 is released.
61 is input. The output signals of the latch circuits 60 and 61 are:
The output signal of the latch circuit 61 is input to the AND circuits 64 and 65, and the output signal of the latch circuit 61 is input to the AND circuits 64 and 65.
It is input to circuit 67. strobe strobe 1
2 is turned on, an "H" strobe use signal is output and sent to the AND circuit 64 and the transistor 68. An electromagnet 42 for driving the aperture plate 35 is connected in series to this transistor 68. In addition, the signal obtained by inverting the strobe use signal with the inverter 69 is the AND
It is input to circuits 65 and 67. Note that if the strobe automatically emits light by measuring the brightness of the subject, it is sufficient to extract a signal indicating that the strobe is in operation. The output signal of the AND circuit 64 is inverted by an inverter 70 and then input to an AND circuit 71. This AND circuit 71 and the AND circuit 6
5 and 67, the distance measurement end signal outputted from the drive circuit 52 is also input. The base of a transistor 74 is connected to the output terminal of the AND circuit 71, and the AND circuit 7
When the output signal of No. 1 is "H", the transistor 74
conducts and excites the electromagnet 21. A relay 75 is connected to the output terminal of the AND circuit 65, and the output signal of the AND circuit 65 is "H".
When , the relay 75 is activated and the relay switch 76 is activated.
Switch from contact a to contact b. A relay 77 is connected to the output terminal of the AND circuit 67, and when the output signal of the AND circuit 67 is "H", the relay switch 78 is switched from contact a to contact b. This contact a is grounded, and the contact b is at a positive potential. The distance measuring device 45 operates in conjunction with pressing the release button 8, stores the obtained distance measurement information in latch circuits 60, 61, and activates the electromagnet 21 and relays 75, 76 in response to a distance measurement end signal. is activated.
The operation of the main elements of the circuit shown in FIG. 4 is shown in the following table.

[Table] Figures 5 and 6 show an embodiment in which the distance measurement zone is changed by swinging one light receiving section. In FIG. 5, the near-infrared light emitted from the near-infrared light emitting diode 80 is
It passes through the lens 81 and proceeds parallel to the optical axis of the photographing lens 9. The near-infrared light reflected by the subject passes through the lens 8.
2 and enters the light receiving element 83. These lenses 82 and light-receiving elements 83 are provided so that their orientation can be changed, and are set to the light-receiving angle shown by the solid line when shooting during the day without using a strobe, and to the light-receiving angle shown by the dotted line when using the strobe. Set. FIG. 6 shows the distance measurement zone switching mechanism. The lens 82 and the light receiving element 83 are mounted on a lever 86 that is supported by a shaft 85 .
A pin 87 provided on this lever 86 fits into a groove 88a of an interlocking lever 88. solenoid 89
When the plunger 90 of is retracted, the shaft 91
The interlocking lever 88 rotates clockwise around , causing the lever 86 to rotate counterclockwise. As a result, the central axis of the light receiving element 83 changes from 92 to 9.
Since it changes to 3, the distance measurement zone changes. The solenoid 89 is energized by a strobe use signal (when the strobe switch 12 is turned on). Furthermore, in the circuit shown in FIG. 4, the light receiving section 5 is configured to be switched between daytime photography and strobe photography, and the light receiving section 6, amplifier 54, and comparator 5
8. By omitting the latch circuit 60 and inputting the output of the latch circuit 61 to the input terminal of the latch circuit 60 of the AND circuit 64, the embodiments shown in FIGS. 5 and 6 can also be used. FIG. 7 shows the relationship between the shooting distance and the circle of least confusion when the lens set position is set at 1.35 m and 2 m during strobe photography. The photographic lens used was f=40mm, and the aperture was set to a maximum aperture (F2.8). In addition, a strobe with a guide number of 7.5 was used. The minimum circle of confusion is approximately 0.07 up to a distance of 2.68m where strobe photography is possible.
It can be kept within. FIG. 8 shows the relationship between the photographing distance and the circle of least confusion when the lens set position is set at 1.5 m and 4 m during daytime photographing. At this daytime shooting distance, the aperture is adjusted by the aperture plate mentioned above.
It is set to F4.6. Lens set position 1.5
By simply setting two points, m and 4m, and performing two-point zone focus, the circle of minimum confusion can be kept within 0.07 over the range of 1.2m to 20m, and INF
can also be set to 0.087. The present invention having the above configuration changes the boundary between the near zone and the far zone and changes the lens set position for daytime photography and strobe photography. In addition, in strobe photography where many shots are taken at close range and the aperture is wide open, it is possible to clearly capture objects that are at a distance that allows strobe photography.

[Brief explanation of drawings]

FIG. 1 is a front view of a camera embodying the present invention. FIG. 2 is a sectional view showing the lens setting mechanism. FIG. 3 is a perspective view showing the diaphragm. FIG. 4 is a schematic diagram showing the electrical configuration of the present invention. FIG. 5 is an optical path diagram showing another embodiment for switching distance measurement zones. FIG. 6 is a plan view showing the distance measurement zone switching mechanism. FIG. 7 is a graph showing the relationship between the photographing distance and the circle of least confusion during strobe photography. FIG. 8 is a graph showing the relationship between the photographing distance and the circle of least confusion during daytime photographing. 3... Strobe light emitting section, 4... Light projecting section, 5, 6
... Light receiving section, 7 ... Finder, 9 ... Photographing lens, 10 ... Movable lens barrel, 12 ... Strobe switch, 15 ... Lock lever, 21 ... Electromagnet, 2
3...Positioning lever, 24...Step tooth, 28...
Coil, 32...Bar magnet, 35...Aperture plate, 42
...Electromagnet, 36...Shutter, 37...Film, 46...Near-infrared light emitting diode, 49,5
2... Light receiving element, 54, 55... Amplifier, 56,
57... Comparator, 60, 61... Latch circuit, 80... Near-infrared light emitting diode, 83... Light receiving element, 89... Solenoid.

Claims (1)

[Scope of Claims] 1. A distance measuring device that performs distance measurement with a distance closer than a certain subject distance as a distance measurement zone during normal shooting without using a strobe, and detects the presence or absence of a subject within the distance measurement zone. In an autofocus camera, the photographing lens is set to either a short distance setting position or a long distance setting position according to a signal from the distance measuring device, and a shooting switching means for switching between normal shooting and strobe shooting; A distance measuring zone changing means detects that the photographing switching means has switched to strobe photography, changes the constant subject distance to a short distance side, and sets a distance measuring zone for strobe photography; An autofocus system with a built-in strobe, comprising a lens set position changing means for changing the short distance set position and long distance set position of a photographing lens to a shorter distance side than during normal shooting during distance measurement using a zone. camera. 2. The distance measuring device includes a light projector that projects near-infrared light, and two light-receivers arranged to receive the near-infrared light reflected by the subject and having different reception angles. The built-in strobe according to claim 1, characterized in that the built-in strobe according to claim 1 is adapted to select one of these light-receiving parts and output an output corresponding to normal photography and strobe photography. auto focus camera. 3. The distance measuring device has a light projecting section that projects near-infrared light, and a light receiving section that receives the near-infrared light that is reflected by the subject and returns, and can be used during normal shooting and strobe shooting. An autofocus camera with a built-in strobe according to claim 1, characterized in that the direction of the light receiving section is changed in response to the above.