JP2529360B2 - Camera with electric zoom lens - Google Patents

Description

The present invention relates to a camera with an electric zoom lens capable of stroboscopic photography.

[Conventional technology]

Recent compact cameras are used as shooting lenses.
In addition to the conventional two-focal point switching type, a type using an electric zoom lens has been provided.
Since the zoom lens of such a compact camera is premised on being low cost, unlike a high-end zoom lens for a single-lens reflex camera, a type in which an effective F value (F number) is changed by zooming is adopted. It is normal to have

Therefore, when stroboscopic photography is performed with such a camera, overexposure occurs on the wide side where the brightness of the lens becomes brighter, and underexposure occurs on the telephoto side where it becomes darker. In order to correct this, a conventional camera is known in which the guide number of the strobe is changed according to the effective F value of each focal length. In addition, as exposure adjustment at each focal length, it is known to employ a flashmatic mechanism that automatically adjusts the aperture diameter of the taking lens according to the subject distance.

[Problems to be Solved by the Invention]

However, the above-mentioned camera has a drawback that underexposure occurs when the distance to the subject exceeds the adjustment range of the flashmatic mechanism even if the flash guide number is set to the maximum.

[Object of the Invention]

The present invention has been made to solve the above-described problems, and provides an electric zoom lens-equipped camera that prevents underexposure and allows a wide range of stroboscopic photography. With the goal.

[Means for solving the problem]

To achieve the above object, in the camera with the electric zoom lens of the present invention, the zooming position of the electric zoom lens is not at the wide-angle end that is brighter than the telephoto side, and the determination means is based on the brightness of the lens and the subject distance at that time. When it is determined that the exposure is insufficient, the zooming correction unit zooms the electric zoom lens to the wide-angle side.

[Action]

According to the above configuration, when performing flash photography under low illuminance, it is determined whether or not there is underexposure based on the brightness of the lens and the subject distance at the zooming position at that time. The stroboscopic photography is executed as it is, and when the underexposure occurs, the electric zoom lens is zoomed to the wide angle side by the zooming correction means, and then the stroboscopic photography is performed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

〔Example〕

In FIG. 4 showing a camera 1 according to an embodiment of the present invention, a fixed barrel 3 is attached to a front surface of a camera body 2, and a movable barrel 5 holding a zoom lens 4 for photographing is incorporated therein so as to be movable back and forth. Has been. Above the fixed barrel 3, a finder window 6, distance measuring windows 7a and 7b for autofocus, and a photometric window 8 are provided. A seesaw knob 9 for zooming and a strobe light emitting portion 10 are provided on the right side of the fixed barrel 3 in the drawing. On the upper surface of the camera body 2, a mode switching operation member 11 for a built-in flash, a hot shoe 12 for mounting an external flash, and a shutter button 14 are provided. The shutter button 14 is of a two-step push type in which distance measurement and photometry are performed in the first step and the shutter is released in the second step.

A zoom finder (not shown) is built in the back of the finder window 6, and a distance measuring device 16 including a light projector and a light receiver for distance measurement is provided behind the distance measuring windows 7a and 7b (see FIG. 2). ) Is stored. Further, behind the photometric window 8 is an EE sensor (for example, SPD) 17 that measures the brightness of the subject (see FIG. 2).
Is stored.

The seesaw knob 9 is normally in the illustrated neutral position. When the index "T" side is pressed, the zoom lens 4 and the zoom finder are zoomed toward the telephoto side only during the pressing, and when the index "W" side is pressed, the zoom lens 4 and the zoom finder are zoomed toward the wide angle side. It Of course, if the pressing of the seesaw knob 9 is released during the magnification change, the zoom lens 4 and the zoom finder stop the magnification change at that time.

The mode switching operation member 11 is located at any one of the low-brightness automatic light emission mode position indicated by the mark "AUTO", the daytime synchronization mode position indicated by the mark "ON", and the light emission stop mode position indicated by the mark "OFF". Locked. The low-brightness automatic flash mode allows the flash unit 10 to automatically
Switch from EE shooting to flash shooting. In the daytime sync mode, daytime sync photography can be performed using the strobe light of the strobe light emitting section 10 as auxiliary light regardless of the subject brightness. In the light emission stop mode, the low-brightness automatic light emission mode is canceled, and the flash light emitting unit 10 does not emit light.

In FIG. 2 showing the outline of the internal structure of the camera 1 of the present invention, the zoom lens 4 includes a focusing lens 20 that is moved forward and backward in the optical axis direction to focus, and a movable barrel 5.
From the zoom lens 21 for moving the focal length of the zoom lens 4 and the rear lens group 22 for focusing the light flux transmitted through the focusing lens 20 and the zoom lens 21 on the photosensitive material. Become.

The focusing lens 20 is moved back and forth by a motor 23 via a gear train or the like, and a focusing drive circuit 24 for driving the motor 23 is connected to the motor 23. Further, the variable power lens 21 is moved back and forth in the optical axis direction by a stepping motor 25, and a zooming drive circuit 27 for driving the stepping motor 25 is connected to the stepping motor 25. Although not shown, a stepping motor
The 25 is used not only to move the zoom lens 21 but also to move the zoom lens of the zoom finder at the same time, and the photographer can select the desired angle of view while checking the condition of the subject with the zoom finder. .

To the focusing drive circuit 24 and the zooming drive circuit 27, a microprocessor unit (hereinafter abbreviated as MPU) 30 that operates according to a sequence program written in a program ROM 28 is connected. Further, in addition to the focusing drive circuit 24, the zooming drive circuit 27, the release signal generating circuit 31,
A strobe mode setting circuit 32, a shutter drive circuit 33, a strobe drive circuit 34, a film feed drive circuit 35, a RAM 36, the distance measuring device 16, and an EE sensor 17 are connected.

The release signal generation circuit 31 converts the pressing operation of the shutter button 14 into a release signal and sends it to the MPU 30. The strobe mode setting circuit 32 sets the mode according to each position of the mode switching operation member 11, and outputs this mode data.
Send to MPU30. Further, the shutter drive circuit 33,
The motor 38 connected to this is driven by the command signal of the MPU 30, and the program shutter 40 is opened and closed.

The strobe drive circuit 34 charges a main capacitor (not shown) by a charge signal from the MPU 30 and causes the strobe light emitting section 10 to emit light when receiving a trigger signal. The film feed drive circuit 35 is provided when the film is loaded, after opening and closing the program shutter 40, and when rewinding.
Motor 42 for film feeding based on the command signal of MPU30
Drive. The RAM 36 is a writable and readable memory for temporarily recording various data such as distance measurement data, zooming position data, photometric data, and various calculation results.

FIG. 3 is a graph showing the relationship between the zooming position of the zoom lens 4 and the effective F value. Symbol F _T in the figure
Indicates the effective F value when the zooming position is at the telephoto end, and the symbol F _W indicates the effective F value when the zooming position is at the wide end, and F _W <F _T. If the zooming position is s, the effective F value F is represented by a function f (s), for example, F ₁ = f (s ₁ ).

The operation of the camera 1 of the present invention configured as above will be described. First, load the film into the film chamber of the camera 1, align the mode switching operation member 11 with the mark "AUTO",
Aim the zoom lens 4 at the subject. While observing the subject with the zoom finder, operate the seesaw knob 9 to search for a desired magnification. At this time, zoom drive circuit 2 from MPU30
A drive command is sent to 7, the stepping motor 25 is driven, the zoom lens 21 is advanced and retracted, the zoom lens 4 is zoomed, and at the same time, the zoom finder is zoomed. When the desired magnification is determined, remove your finger from the seesaw knob 9.

Hereinafter, description will be given based on the flowchart shown in FIG. Since the angle of view has been determined, the shutter button 14 is lightly pressed to be half pressed. As a result, the release signal generating circuit 31 sends a half-press release signal to the MPU 30, and the MPU 30 drives the distance measuring device 16. The ranging device 16 detects the ranging data D and sends it to the MPU 30, which the MPU 30 stores in the RAM 36.
To record.

At the same time, the zooming drive circuit 27
The position data s ₁ is detected and the position data s ₁ is sent to the MPU 30. The MPU 30 records the position data s ₁ in the RAM 36, and at the same time, the effective F of the zoom lens 4 corresponding to the position data s ₁ is recorded.
The value is calculated from the function F = f (s), and the obtained effective F value F ₁ is recorded in the RAM 36.

Subsequently, the MPU 30 calculates the proper exposure value P based on the photometric data from the EE sensor 17, and records it in the RAM 36.
When the appropriate exposure value P is less than or equal to a predetermined value P ₀ (for example, 7EV), the MPU 30 determines that it is at a low brightness when auxiliary strobe illumination is required, and sends a charging signal to the strobe drive circuit 34. Start charging the main capacitor. Further, based on the distance measurement data D, a drive signal is sent to the focusing drive circuit 24 to drive the motor 23 to move the focusing lens 20 for focusing.

Since the mode switching operation member 11 is in the low-brightness automatic light emission mode position, the MPU 30 performs a flashmatic (abbreviated as FM in FIG. 1) calculation to obtain a proper flash emission corresponding to the distance measurement data D. The aperture value A is calculated. Then, the aperture value A is the effective F value recorded in the RAM 36.
Compare with the value F ₁ .

As a result, if F ₁ ≦ A, the shutter drive circuit 33 opens the program shutter 40 after the aperture of the zoom lens 4 is reduced to the aperture value A by fully pressing the shutter button 14. At that moment, a trigger signal is sent to the strobe drive circuit 34, the strobe light emitting section emits light, and the program shutter 40 is closed. Subsequently, the film feed drive circuit 35 drives the feed motor 42 to move the film by one frame, and the program shutter 40 is charged to prepare for the next photographing.

When F ₁ > F, the exposure is underexposed when shooting is performed as it is, so the effective F values F ₁ and F _W are compared. As a result, if F ₁ ≠ F _W , a command signal is sent to the zooming drive circuit 27 to move the variable power lens 21 in the wide side direction. Each time the stepping motor 25 moves the variable power lens 21 one step, the zooming position s ₂ of the variable power lens 21 is detected, and the effective F value F ₂ corresponding to that position is calculated.

This effective F value F ₂ is compared with the aperture value A, and as a result, F ₂ =
When the time reaches A, the MPU 30 sends a stop signal to the zooming drive circuit 27 to stop the zooming of the zoom lens 4. In this state, if the shutter button 14 is pressed all the way down, flash photography with proper exposure is performed. Also, even if you zoom to the wide end and F ₂ = F _W , F ₂ = A does not hold, that is, if A <F _W , the LED in the viewfinder
Flashes (not shown) to warn you that you will be underexposed.

If the zooming position is at the wide end from the beginning, the LED in the viewfinder will blink to warn you that underexposure will occur even if you use the flash. The photographer who saw the warning marks the mode switching operation member 11 with the "OF
"F", for example, the hot shoe 12 and the flash unit 1
Shoot with a method such as mounting an external flash unit with a guide number greater than 0.

As described above, the mode switching operation member 11 has the mark "OF
When it is in `` F '' or when an external strobe is attached,
Flashmatic and automatic zooming toward the wide side are canceled.

It is also known that a strobe does not emit light when the subject has a high brightness, but during a backlit scene, a beautiful picture can be taken by performing daytime synchronized photography using the strobe as auxiliary light. Therefore, when the brightness is high, if the mode switching operation member 11 is set to the daytime synchronization mode position in accordance with the mark “ON”, the strobe light emitting unit 10 emits light in synchronization with opening and closing of the program shutter 40.

In the above description, the “flashmatic method” that adjusts the aperture of the shooting lens according to the distance to the subject was adopted as the method of strobe shooting, but so-called “auto strobe” that adjusts the amount of light emitted by the strobe according to the brightness of the subject is used. May be used. In this case, it is determined from the distance data to the subject obtained by the distance measuring device of the camera and the guide number of the automatic strobe whether or not the light amount becomes insufficient before the light emission. When it is predicted that the amount of light will be insufficient, the zoom lens is moved toward the wide side in the same manner as in the above-described embodiment, and the amount of light is insufficient even when the end portion on the wide side is reached, or the zooming position is already on the wide side. The same effect as that of the above-described embodiment can be obtained by configuring so as to issue a warning when it is at the end.

〔The invention's effect〕

As described above, according to the camera with the electric zoom lens of the present invention, the zooming position of the electric zoom lens is not at the end on the wide angle side which is brighter than the telephoto side, and the determination unit is exposed based on the brightness of the lens and the subject distance at that time. If it is determined that the shortage will occur, the zoom lens will be used to zoom the electric zoom lens to the wide-angle side, so underexposure during flash photography will be automatically prevented and a wider range of flash photography will be possible. It becomes possible to provide a camera with an electric zoom lens that is capable of performing the above.

[Brief description of drawings]

FIG. 1 is a flowchart adopted in the embodiment of the present invention. FIG. 2 is a block diagram schematically showing the structure of the embodiment of the present invention. FIG. 3 is a graph showing the relationship between the effective F value and the zooming position of the zoom lens of the embodiment of the present invention. FIG. 4 is a perspective view showing the external appearance of an embodiment of the present invention. 1 …… Camera 4 …… Zoom Lens 9 …… Seesaw Knob 10 …… Strobe emission part 11 …… Strobe mode switching operation member 12 …… Hot shoe 27 …… Zooming drive circuit 30 …… MPU 32 …… Strobe mode setting circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-53-48728 (JP, A) JP-A-61-223830 (JP, A) JP-A-61-113039 (JP, A) JP-A-59- 111133 (JP, A) Actual development Sho 59-173039 (JP, U)

Claims (1)

(57) [Claims] 1. An electric zoom lens for changing the brightness of the lens to become darker on the telephoto side and brighter on the wide-angle side according to zooming, distance measuring means for measuring a subject distance, and a zooming position of the electric zoom lens. Detecting means for detecting, a determination means for determining whether or not underexposure is based on the brightness of the lens and the subject distance at the zooming position during flash photography under low illuminance, and based on the determination result of this determination means. A camera with an electric zoom lens, which is provided with zooming correction means for zooming the electric zoom lens to the wide-angle side.