JPH0392832A - Camera - Google Patents

Abstract

PURPOSE:To realize a photographing without missing a shutter chance in case of emergency by providing an exposure control means which carries out an exposing action based on an absolute distance calculated by a focusing means if a lens carrying inhibiting means is inoperable when a shutter releasing means is set to a second status following a first status. CONSTITUTION:When the shutter releasing means 1 is set to a second status before a photographing lens 6 is started to be carried to a prescribed position or before its completion after the means 2 is set to the first status, the lens carrying inhibiting means 12 inhibits the carrying of the photographing lens 6. The exposure control means 13 calculates exposure without using absolute distance information when the focusing means 4 does not calculate an absolute distance by activating the lens carrying inhibiting means 12. When an absolute distance is calculated without activating the lens feed inhibiting means 12 an exposure value is calculated through the use of absolute distance information, and exposure is performed based on each exposure value. Consequently, a picture can be taken without missing a shutter change in case of emergency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for retracting the photographic lens to a predetermined position such as infinity and resetting the data, and then retracting the photographic lens from the amount of extension to the in-focus position to the subject. This invention relates to a camera that calculates the absolute distance of a camera.

[Prior Art] Conventionally, as a camera of this type that performs exposure control by determining the absolute distance to the subject, there is a camera such as Japanese Patent Laid-Open No. 61-292608.

This method of determining the absolute distance to the subject is such that when you turn on the camera by pressing the shutter button halfway, etc., the photographing lens is retracted to the infinite position, the data is reset there, and then the subject is in focus. Moving on to the focusing operation of extending the photographic lens, the amount of extension of the photographic lens from the infinite position at this time was measured to calculate the absolute distance.

[Problems to be Solved by the Invention] However, in such conventional technology, after the photographic lens is retracted to a predetermined position, the focus adjustment operation is started, which causes a considerably long time lag before the start of exposure. death,
This has the problem that a photo opportunity may be missed.

The present invention was developed in view of these conventional problems, and employs a method of calculating the absolute distance to the subject from the amount by which the photographic lens is extended to the in-focus position after being retracted to a predetermined position. To provide a camera that can take pictures without missing a photo opportunity in an emergency even when the camera is closed.

[Means for Solving the Problems] In order to achieve this object, the camera of the present invention includes a shutter release means that can set at least a first state and a second state; When set to state 1, a focus matching means moves the photographing lens to a predetermined position, and then performs a focus matching operation to a subject focusing position to calculate the absolute distance to the subject; and the focal point. When the shutter release means is set to the second state before the alignment means starts or completes the movement of the photographic lens to the predetermined position, the subsequent movement of the photographic lens to the predetermined position is prohibited. Lens retraction inhibiting means for performing only a focus matching operation; when the shutter release means is set to a second state following the first state, if the lens retracting inhibiting means is inactive, the focus matching means; and an exposure control means for performing an exposure operation based on the absolute distance calculated in the above.

[Function] In the camera of the present invention having such a configuration, for example, when the shutter button is pressed all the way at once during emergency photography, the photographing lens is retracted to a predetermined position by the function of the lens retraction prevention means. Since the focus adjustment operation or exposure is performed without any delay, it is possible to take pictures without missing a photo opportunity.

[Embodiment] FIG. 1 is a block diagram of a camera showing an embodiment of the present invention.

In FIG. 1, 1 is a shutter release means, and when the shutter button 2 is pressed halfway, a switch 3a is set to a first state 3c.
When set to , the focusing means 4 rotates the motor 5 to move the photographing lens 6 to an infinite position. That is, the retracting operation of the photographing lens 6 to the infinite position is performed. Then, at the infinite position, the infinite position switch 7
When the convergence is detected, the focusing means 4 stops the rotation of the motor 5 and resets the absolute distance information to the subject stored at that time. Next, depending on the amount of defocus detected by the focus detection means 1, the focus adjustment means 4 rotates the motor 5 to move the photographic lens 6 to the in-focus position of the subject.

Here, the focus detection optical system for detecting the amount of defocus by the focus detection means 11 uses the re-imaging optical systems 9a and 9b to refocus the object image on the predetermined focal plane 8 into the distance measuring element array 10a.
10b, and the focus detection means 11 calculates the amount of defocus based on the detection signal of this image position.

When the focus matching operation is completed, the focus matching means 4 converts the amount of movement of the photographic lens 6 from the absolute position into an absolute distance X to the subject and outputs it to the exposure control means 13, and also displays the focus on the display means 14. Perform display. When the photographer sees this focus display and fully presses the shutter button 2 to set the switch 3a to the second state 3d, the exposure control means 13 performs exposure and ends the photographing.

Next, after the shutter release means 1 is set to the first state, if the second state is set before the retraction operation of the photographing lens 6 to a predetermined position is started or completed,
A lens retraction inhibiting means 12 prohibits retraction of the photographic lens 6.

When the AF drive mode is set to the continuous AF servo mode by a mode setting means (not shown), exposure is started at that lens position, and when the AF drive mode is set to the single AF servo mode, the photographing lens 6 is started. Move the lens to the in-focus position and start exposure after focusing.

Here, when the lens retraction inhibiting means 12 is activated and the absolute distance X is not calculated, the exposure control means 13 calculates the exposure value without using the absolute distance information shown in FIG. 3. If the absolute distance X is calculated without the lens retraction prohibition 12 not operating, the exposure value is calculated using the absolute distance information according to FIG.

FIG. 3 shows the exposure value calculation process by the exposure control means 13 when the absolute distance X is not calculated due to the operation of the lens retraction inhibiting means 12.

In FIG. 3, for example, four types of exposure value calculation methods CW
, BM, BLM, and BHM are used. That is, the maximum brightness difference Δ, which is the difference between the maximum brightness Bmax and the minimum brightness Bmn, is plotted on the horizontal axis by the maximum brightness Ba+ax among the five brightnesses 81 to B5 of the subject obtained from a multi-photometering means (not shown).
B is taken, and one of the four types of exposure value calculation methods is selected based on the values of Bmax and ΔB.

These four types of exposure value calculation methods CW, BM, B
LM and BNM are expressed by the following equations.

CW=81 (luminance of central area) BM= (B1+B2+B3+B4+B5)/5BLM
= (BM+Bmin)/2 BHM= (BM+B+nax)/2 That is, CW is an exposure value that emphasizes the central area of the field, BM is an exposure value based on the average value of each metering area 1 to 5, and BLM is a low BHM obtains an exposure value weighted to brightness, while BHM obtains an exposure value weighted to high brightness.

Further, b1 to b4 are constants preset for the maximum brightness Bmax, and at to a3 are constants preset for the maximum brightness difference ΔB.

For example, in FIG. 3, if the maximum brightness is b3<Bmax≦b4 and the maximum brightness difference is a<ΔB, the BLM method is selected, and an exposure value weighted toward low brightness is calculated using the BLM calculation formula. .

FIG. 4 shows the calculation contents of the exposure value when the absolute distance X is detected without the lens retraction inhibiting means l2 operating.

In FIG. 4, three tables x, y, and 2 are provided, which are selected based on the ratio x/f between the absolute distance X to the detected object and the focal length f of the photographic lens 6.

The conditions for selecting this table are as follows.

(x/f)≦20 X table 20<(x/
f)≦100 Y table 100< (x/f)
Similarly to Figure 3, each of the Z tables x, y, and z has the maximum brightness Bmax on the horizontal axis and the maximum brightness difference ΔB on the vertical axis, and the table contains four types of exposure value calculation methods CW. , BM, BLM, and BHM.

To explain specifically, the current f=50mm photographic lens 6
If the absolute distance X is 1 m x <5 m, table Y is selected because this is mainly a photograph of a person. Table Y includes many CW systems that place emphasis on the center area and BLM systems that place emphasis on low brightness.

Further, when F=50 mm and the absolute distance X is x>5 m, two tables are selected. This is mainly landscape photography, and therefore the Z table contains many <BM methods based on average values.

FIG. 2 is a flowchart showing an algorithm of an embodiment of the present invention.

In step SL (hereinafter "step" will be omitted), when the first state is set in the shutter release means 1, the process proceeds to 82, where it is determined whether or not the second state has been set. If the second state is set, the process advances to S7; if not, the process advances to S3, where retraction of the photographing lens 6 to the infinite position is started. If the setting of the second state is determined at 84 during the renormalization operation of the photographic lens 6, the process proceeds to S7, and if the setting is not determined, the process proceeds from S4 to 85.
The renormalization to the infinite position is completed, and the absolute distance information for the subject is reset in S6.

In S7, a focus matching operation is performed to move the photographing lens to the in-focus position of the subject, and in S8, focus determination is performed, and if the object is in focus, an in-focus display is performed in S9. Of course, when the focusing operation is completed and the reset is being performed by renormalizing S5 and S6 to the infinite position,
The absolute distance X to the subject is calculated based on the amount of lens extension from the infinite position.

If focus is not determined in S8, an out-of-focus display is displayed at $10, the process returns to S7, and this routine is repeated until focus is achieved.

In Sll after completion of focusing, the camera waits until the second state is set by the shutter release means 1, and when the second state is set, the process advances to 812, where exposure is performed and the photographing ends.

In the exposure operation of SL2, if the absolute distance The exposure value is calculated by the method shown in FIG. 3 that does not use the absolute distance X, and the exposure operation is performed based on each exposure value.

In this embodiment, the predetermined retraction position of the photographic lens 6 is set to an infinite position, but the invention is not limited to this.
It does not matter if it is an infinite position, a regular position, or a close position.

Further, the present invention is not limited to the above-mentioned embodiments, and for example, when the lens retraction inhibiting means 12 is activated and the absolute distance X is not calculated, the previously calculated absolute distance
By storing, the absolute distance X may be used to calculate the exposure value. Furthermore, in the case of the above embodiment, absolute distance information is used to calculate the exposure value, but the information is not limited to this; for example, the information may be used for aperture control during strobe photography, or the focus detection area It may also be used for switching between spots and wide areas.

[Effects of the Invention] As explained above, according to the present invention, when the shutter button is pressed all the way at once during emergency photography, the lens retracting prevention means prevents the photographing lens from retracting to a predetermined position. Since the focus adjustment operation or exposure is performed, it is possible to take pictures without missing a shutter opportunity.

[Brief explanation of drawings]

Figure 1 is a block diagram of a camera showing an embodiment of the present invention; Figure 2 is a flowchart showing the algorithm of the present invention; Figure 3 is an explanation showing the exposure value calculation process that does not use the absolute distance of the subject. Figure: Figure 4 is an explanatory diagram showing the exposure value calculation process using the absolute distance of the subject. [Explanation of symbols of main parts] Work: Shutter release means; 4: Focusing means; 12: Lens retraction prevention means; 13: Exposure control means;

Claims (1)

[Claims] (1) A shutter release means capable of setting at least a first state and a second state; When the shutter release means is set to the first state, the shutter release means moves the photographing lens to a predetermined position. a focus matching means for calculating the absolute distance to the subject by performing a focus matching operation to a subject focusing position; , a lens retraction inhibiting means for prohibiting a subsequent movement of the photographing lens to a predetermined position and performing only a focusing operation when the shutter release means is set to a second state; The second state follows the first state.
1. An exposure control means for performing a photographing operation based on the absolute distance calculated by the focus matching means if the lens retraction inhibiting means is not activated when the camera is set to the above state.