JPH02165128A - camera - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to cameras, and in particular to cameras having an external photometric device.

[Conventional technology]

In recent years, there have been an increasing number of cameras that use silver halide film as a sensitizer, even in the field of compact cameras for beginners, that have increased the amount of extension of the focusing lens, making it possible to cast shadows at close distances of 111 m.

- On the other hand, among video cameras using photoelectric conversion elements such as COD as a sensitizer, compact cameras are being released for general users, similar to cameras using the silver halide film described above.

In this way, in a camera that has been made more compact by increasing the extension amount of the focusing lens, the development latitude (tolerance) is wide in the case of silver halide film, but C
Since the latitude of development in the case of a photoelectric conversion element such as a CD is extremely narrow, in a video camera using these light 1'' conversion lines, exposure control during shooting must be carried out in the same way.

Furthermore, since the screen size of video cameras is smaller than that of silver halide film cameras, even popular types aimed at compactness are likely to have longer focal lengths, and furthermore, it is expected that the amount of extension of the focusing lens will increase.

(One Problem to be Solved by the Invention) As described above, in the conventional example, when the photographing lens has a long focal length and the distance to the subject is short, the imaging magnification or the effective F' This causes a change in 'C exposure error,
There was a problem in that it had a large effect on exposure accuracy (described in detail later).

In addition, cameras without conventional external photometry devices perform direct exposure 1 control based on the photometry output from the photometer that measures light at a position different from that of the photographic lens. ; There was a problem in that it was not possible to detect changes in the effective F lumbar based on thermal information.

This invention was made in order to solve the above-mentioned problems of the prior art. I hesitated and decided to create a camera that can automatically add compensation to the 1-stage exposure compensation control and determine a high-resolution exposure value.
ll to be [I].

(F stages for solving the problem) For this reason, in the present invention, exposure control stages I and C, which perform exposure control based on the photometric output from the photometry means A that performs photometry at a position different from that of the photographic lens, are provided. In a camera equipped with a focus detecting means B that automatically detects a focus, the focus detecting means B instructs 11ii recording (large extension of the r lens 1; 1, and the imaging lens of the photographing lens is When the magnification exceeds a predetermined value, the effective F-nanometer value is calculated and adjusted to the exposure value obtained by 1!'l from the first step of photometry.
This is an attempt to achieve the above-mentioned objective 1 by using a camera which adds an exposure compensation 1--control stage p which controls 'i't e+8 by adding jE.

[Effect]

The camera of this invention is that the focus detecting means B instructs a large amount of edge exposure of the 1st lens by the exposure compensation control step, and the image formation of the 1st lens (when the g ratio exceeds a predetermined value). At this time, the effective F-number is calculated, and the supplementary iE is added to the exposure value obtained from the photometry means A to control the exposure.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

11th. 1 is an exploded perspective view showing the configuration of a power mechanism according to an embodiment of the present invention, and 21A is a flowchart for controlling the operation of this embodiment.
Front group of the darkest lens 2. Controls the aperture opening ['' and shirt 4 speed = r lens yatta 3° Rear group 4 of the photographic lens
It is a photographing system composed of a photoelectric conversion element 4, which forms an image of an object on a photoelectric conversion element 5.

Further, 6a and 6b are -FJ'1, respectively, an imaging lens for focus detection, and 7a, ? b is -t, it is a line sensor for focus detection +l, 8 is a focus detection value output generator, and L72
>, f in C): The ozowa constitutes the focus detection means B. , 7, there is a 6-point detection stage B let jF, and a 1 stage that automatically detects the points Llj, and the first image of the fin sensor 7 a 10 formed by the L/lens 6 a and the lens 6 h'? :
'Detecting the intercapsular obstruction of the second image of the image-formed orthogonal line sensor 7b1. ``Measure the distance between the subject and the lens, and use the determined output as the focus detection value output.''
There is a step 'C' from the device 8.

Further, 9 is a focus detection value output generating device 8, Ll
- Receives the X force, drives the 7t T shadow system)) - Casson lens drive unit uM, + 10 &i iji*
,l/? -' , , , 11 G,'l photometric sensor, 12 is photometric output linkage 11: device, t'7.
, tt, etc. 1" constitutes 1ltl light-f stage Δ. The second photometer A is different from the photographing system 1.
It is a 1r step that measures light at +2 positions, and the photometry is 1. The Lfj force measurement likelihood value t11 obtained from the nons 10 and the photometric sensor 11 is one stage read by the force detection 111 device X2. 14 receives the photometric output of the photometric value output detection device 12, and in the conventional case, Qi
It is an exposure control device that determines the aperture value and shutter speed 7 and controls the drive of the aperture drive device 15, and these exposure control devices 14 and the aperture drive device 1
5 constitutes the exposure control means C. This is a conventional case such as 1, which is similar to the Iki surface, but the invention of J.
When the shooting lens has a long focal length and the subject distance is short, the t:Iig output control device 14 and the aperture drive device 15 constitute a ten-stage exposure correction control device. This exposure compensation control means is used to detect the focus from stage B when a large amount of lens is specified. When the imaging magnification for shooting [2. This is a means for controlling the effective jumper value by always adding a correction to the exposure value obtained from the photometry means A by 6° (calculation 1, 2).

Next, the operation of this embodiment will be explained with reference to FIGS. 1 and 2, focusing on the exposure correction control means.

First, before entering into this explanation, the exposure errors and the like mentioned in the problem of the conventional example will be explained in more detail.

As mentioned above, in the case of a compact camera, in order to reduce costs and simplify the configuration, external light metering is performed using light metering means A that measures light at a different position than the i-shadow lens. Unlike camera-type TTLill light, which allows photometry to take into account the extension of the lens, direct photometry cannot be performed by taking into account the extension of the photographic lens. Furthermore, in the case of a compact camera in which the photographing lens has a long focal length and the subject distance is short, as in this embodiment, the imaging magnification changes the effective F-number value, causing an exposure error. This error will be explained below with an example.

For example, in a camera using a 2/3" CCD, the focal length of the photographing lens is 25 InIm, and the close distance to the subject is 30 cm. In this case, the imaging magnification is... .1. Also, the effective F number is F a
rt = F (El (1+lβl) ・------
Calculated using equation (2). In this case, β is the imaging magnification, and Fo is the F number of ■. By calculating this formula (2), Fefr, which is the effective F number at close range, is
C, it will be about 1.1 times the number. From this value, an error of 0.2 to 0.3 steps will occur in the F number as an exposure value. In the case of a video camera, the exposure depth is required to be around ±0.5 steps due to the narrow latitude, and when taking into account errors in shutter speed, aperture opening, etc., the effective F.
The influence of the change in number value is larger than the above value (0.2 to 0.3 steps) and cannot be ignored.

In consideration of the fact that direct photometry cannot be performed taking into account the rim of the photographic lens mentioned above and the change in the effective F-number value, in this embodiment, the focus detection means B detects the subject distance, and the effective F-number is The number value is calculated by the exposure correction control means, and the exposure value obtained from the photometry means A is corrected and controlled.

Next, with reference to the flowchart of FIG. 2, the main operations of this embodiment will be explained once again.

In the flowchart of FIG. 2, the process starts in step 2a, the distance between the subject and the lens is detected by the focus detection means B in step 2b, and the image is formed using the formula (1) from the subject distance and focal length in step 2C. After calculating the magnification, proceed to step 2d. In step 2d, the magnitude of the imaging magnification and a predetermined value (for example, 0.1 in the above example calculation) is determined, and if the imaging magnification is larger than the predetermined value, step 2e
Then, the effective F number is calculated using the above equation (2). Next, substitute Faff, the effective F number obtained in step 2e, into the formula 2EV=F'are/t (EV is the corrected exposure value, t is the exposure time 5ec) to obtain the exposure value obtained from the photometer. After the correction is applied, the process proceeds to step 2g to take a photograph using this corrected exposure value, and when the photographing is completed in step 2h, the process ends. If not completed, return to step 2b and repeat.

Incidentally, in step 2d, the Ja level where the imaging magnification is equal to or smaller than the predetermined value is normal F. With 0 number and exposure value, Jl!
Then proceed to step 21) and step 2h.

As described above, according to this embodiment, accurate exposure control can always be performed regardless of the amount of extension of the focusing lens (photographing lens).

(Effects of the Invention) As explained above, according to the present invention, the camera is instructed by the focus detection means to have a large exposure of the photographic lens, and when the imaging magnification of the photographic lens exceeds a predetermined value, , comprising an exposure correction control means which calculates an effective F-number value and corrects the exposure value obtained from the photometry means to control the exposure, thereby automatically adding correction to the exposure value, This has the effect of determining exposure values with high precision.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing the configuration of a camera that is an embodiment of the present invention, and Fig. 2 is a flowchart for controlling the operation of this embodiment.・Photometering means B...Focus detection - 1 step C-...Exposure interval a1 1 step D...Exposure compensation control means 1...Photography system 2. ...Front group 3 of the photographing lens ... Lens shutter 4 ... Rear group 5 of the photographic lens ... CCD photoelectric conversion complete - 8 ...・Focus detection value output generator 9...
) Cassing lens drive device 10...Photometric lens 11...Photometric sensor 12---Photometric output value generator 14...Exposure control device 15...・・Aperture drive device

Claims (1)

[Claims] It has an exposure control means that performs exposure control based on the photometry output from the photometry means that measures light at a position different from that of the photographic lens,
In a camera equipped with a focus detection means for automatically detecting a focus, when a large amount of movement of the photographic lens is instructed by the focus detection means and the imaging magnification of the photographic lens exceeds a predetermined value. The camera is characterized by comprising an exposure correction control means for controlling the exposure by calculating an effective F-number value and adding correction to the exposure value obtained from the photometry means.