JP3906532B2 - Photometric device and camera - Google Patents

Description

【００３７】
一般に、測光値を演算する場合には、測光部における受光素子９から得られる光電流を２を底とする対数に変換した値を用いるいわゆるアペックス方式を用いる。しかし、数式１の演算において測光値を重み付け平均する場合には、対数圧縮された測光値ではなく、受光素子９からの光電流値に比例する真数値で行わなくてはならない。従って、ＢＶｉが対数値である場合には、一度真数値に戻して数式１の演算を行い、その計算値を再び対数圧縮する必要がある。
【００３８】
ステップＳ１１４では、不図示のレリーズボタンが全押しされたか否かを判定し、全押しの場合には、ステップＳ１１５において、求められた測光値ＢＶａに基づいて、絞り２９とシャッター３０を制御し、フィルムへの露光を行い、全押しでない場合には、直接ステップＳ１１６へ進む。
ステップＳ１１６では、半押しタイマーによりレリーズの半押し解除後に所定時間が経過したか否かを判定し、レリーズの半押し継続中又はタイマーが所定時間内であった場合には、ステップＳ１０１へ戻って処理を繰り返し、タイマー切れであった場合には、プログラムを終了する。
【００３９】
本実施形態によれば、以下のような種々の効果がある。
（１）複雑な分割形状の測光素子を用いた測光装置においても、中央部重点測光モードでは、測光感度分布が同心円に近くなる。
（２）スポット測光領域が所定半径を貫くような分割形状の測光素子の場合にであっても、測光感度分布が同心円に近くなる。
（３）選択された焦点検出領域に応じて最適な測光感度分布を持った測光値を得ることができる。
（４）スポット測光領域に対応した領域に焦点検出領域を備えた場合に、最適な測光感度分布を持った測光値を得ることができる。
（５）選択されない焦点検出領域に対応するスポット測光領域の重みを下げることにより、最適な測光感度分布を持った測光値を得ることができる。
（６）焦点調節を自動／手動で行った場合に、最適な測光感度分布を持った測光値を得ることができる。
【００４０】
以上説明した実施形態に限定されることなく、種々の変形や変更が可能であって、それらも本発明の均等の範囲内である。
例えば、分割測光の分割状態は、図４のものに限らず、図１１に示したようなマトリクス状の測光素子であってもよい。この場合に、斜線で示した測光領域Ｍについては、図中のＬで示した光軸から所定半径の円周上での測光感度が、他の円周上と等しくなるような重みによって平均して測光値を求めればよい。このような重み付けで平均すると、所定半径の円周近傍では、測光感度分布が最も同心円状に近くなり、中央部重点測光としては良い特性となる。
【００４１】
【発明の効果】
以上詳しく説明したように、本発明によれば、他の測光モードと兼用の測光素子を用いた場合にも、ファインダ指標と実際の測光感度分布との形状が同じになり、測光誤差の少ない測光装置を提供することができる。
【図面の簡単な説明】
【図１】本発明によるカメラの測光装置の実施形態の構成を示すブロック図である。
【図２】本実施形態に係る測光装置の光学系を示した図である。
【図３】本実施形態に係る測光装置の焦点検出部の構成を示した図である。
【図４】本実施形態に係る測光装置の分割測光の分割状態を示す図である。
【図５】本実施形態に係る測光装置の測光感度分布を示す図である。
【図６】本実施形態に係る測光装置の測光感度分布を示す図である。
【図７】本実施形態に係る測光装置の測光感度分布を示す図である。
【図８】本実施形態に係る測光装置の測光感度分布を示す図である。
【図９】本実施形態に係る測光装置の測光感度分布を示す図である。
【図１０】本実施形態に係る測光装置のアルゴリズムを示すフローチャート図である。
【図１１】他の実施形態に係る測光装置の分割測光の分割状態を示す図である。
【図１２】従来技術の一例を示す図である。
【符号の説明】
１ 撮影レンズ
２ クイックリターンミラー
３ 拡散スクリーン
４ コンデンサレンズ
５ ペンタプリズム
６ 接眼レンズ
７ 測光用プリズム
８ 測光用レンズ
９ 受光素子
１０ 測色用受光素子
１１ 視野マスク
１２ フィールドレンズ
１３ セパレータレンズ
１４ 焦点検出用受光素子
２１ 測光部
２２ 焦点検出部
２３ 領域選択部
２４ ＡＦ／ＭＦ切り替え部
２５ レンズ駆動部
２６ 重み決定部
２７ 露出演算部
２８ 露出制御部
２９ 絞り
３０ シャッタ
３１ マイクロプロセッサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photometric device that measures the luminance of a subject, and more particularly to a photometric device suitable for automatic exposure control of a camera.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, camera photometry devices have photometry modes such as multi-segment photometry, center-weighted photometry, and spot photometry. Multi-segment photometry is a mode in which an object scene is divided into a plurality of parts and metered, and an appropriate exposure value is calculated from each photometric value. Center-weighted metering is a mode that literally focuses on the center of the object scene. Spot metering is a mode in which a very small part of the object is spot-metered.
[0003]
Some cameras have a plurality of built-in photometry modes, and the photographer can select the photometry mode with a changeover switch or the like according to his / her preference. Many of these cameras also serve as photometry elements in each photometry mode, and by averaging the photometric values of a plurality of areas obtained from one photometry element, photometric values corresponding to each photometry mode can be obtained. It is like that.
[0004]
In addition, as shown in FIG. 12, the apparatus disclosed in Japanese Patent Publication No. 7-27152 includes a plurality of focus detection areas F1 to F3 and a plurality of photometry areas. This photometric area includes the first area A including the selected focus detection area, the second area B that is the surrounding area of the first area A, and the third area that is the surrounding area of the second area B. It was divided into three areas C, and the photometric value was calculated by changing the weight of each divided area.
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional camera photometry device, since the center-weighted metering is literally focused on the center of the shooting screen in the metering mode, the sensitivity distribution is concentric around the optical axis. However, when the divided shape of the photometric element is not concentric, the sensitivity distribution may not be concentric and may cause inconvenience.
[0006]
In the apparatus disclosed in Japanese Patent Publication No. 7-27152 described above, the sensitivity distribution of the center-weighted photometry may not be concentric because no consideration is given thereto.
[0007]
Therefore, the present invention provides a photometric device capable of obtaining a photometric value that makes the sensitivity distribution of center-weighted photometry close to a concentric shape even when other photometry modes and photometric elements are used. It is an issue.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention of claim 1 is characterized in that an index indicating a photometric range of a central portion set with respect to the object scene, and a center photometry in which the object scene is positioned corresponding to the index. Photometry that divides into a plurality of areas including a region and a spot photometry area that is located on a line corresponding to the outer shape of the index and extends to the inside and outside of the index, and outputs a photometric value of each area parts and, as the outer shape of the photometric sensitivity distribution of the photometry unit becomes substantially the same as the shape of the indicators, by adding weighted photometric values of the spot metering area photometric value of the central photometric region, a photometric device comprising a photometric value calculation unit that calculates a photometric value of the central photometric region.
[0009]
According to a second aspect of the present invention, in the photometric device according to the first aspect, a focus detection unit that detects a focus state for a plurality of focus detection areas including an area corresponding to the spot photometry area in the object field; And an area selection unit that selects one of the plurality of focus detection areas, wherein the photometric value calculation unit is such that the focus detection area selected by the area selection unit corresponds to the spot photometry area In this case, the photometry device is characterized in that the photometry value of the central photometry area is calculated by increasing the weighting of the photometry value of the spot photometry area .
[0010]
According to a third aspect of the present invention, in the photometric device according to the second aspect , the photometric value calculation unit corresponds the weight of the spot photometric area corresponding to the non-selected focus detection area to the selected focus detection area. The photometric device is characterized in that it is lower than the weight of the spot photometric area .
[0011]
According to a fourth aspect of the present invention, there is provided the photometric device according to the second or third aspect, further comprising a focus adjustment selection unit that selects whether the focus adjustment of the photographing lens is performed automatically or manually, and the photometric value calculation is performed. The photometric device is characterized in that the weight is changed based on an output of the focus adjustment selection unit .
[0012]
According to a fifth aspect of the present invention, there is provided a camera comprising the photometric device according to any one of the first to fourth aspects.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a camera photometry device according to an embodiment of the present invention.
[0015]
The photometry unit 21 is a circuit that measures the object field using a light receiving element such as an SPD (silicon photo diode), and the photometric output is output to the exposure calculation unit 27. As shown in FIG. 4, the photometry unit 21 has a structure in which the object scene is divided into 10 regions BV <b> 1 to BV <b> 10 and photometry is performed, and each luminance value can be output.
[0016]
The focus detection unit 22 can detect the focus for the five focus detection areas FA1 to FA5 shown in FIG. 4, and the information about one area in the focus detection areas FA1 to FA5 based on the information from the area selection unit 23. Detect focus state.
The area selection unit 23 has a structure in which the photographer can arbitrarily select the focus detection areas FA1 to FA5 with an operation member such as a switch, for example.
[0017]
The AF / MF switching unit 24 is a part that outputs a signal for switching whether to automatically or manually adjust the focus of the photographing lens. For example, the AF / MF switching unit 24 has a structure that can be arbitrarily selected by the photographer using an operation switch or the like. Yes.
The lens driving unit 25 is a part that drives the photographing lens 1 shown in FIG. 2 to the in-focus position based on information from the focus detection unit 22 and the AF / MF switching unit 24.
[0018]
The weight determination unit 26 determines what weight is given to each of the photometric outputs BV1 to BV10 from the photometric unit 21 based on information from the focus detection unit 22, the region selection unit 23, and the AF / MF switching unit 24. It is a part to do.
The exposure calculation unit 27 is a part that performs a weighting calculation of a photometric value in accordance with outputs from the photometric unit 21 and the weight determining unit 26 and calculates a final photometric value BVa.
The weight determination unit 26 and the exposure calculation unit 27 are realized by a calculation by a one-chip microprocessor (hereinafter abbreviated as a microcomputer) 31.
[0019]
The exposure control unit 28 is a part that drives the mirror 2, the diaphragm 29, and the shutter 30 based on the output of the exposure calculation unit 27 to expose the film.
[0020]
FIG. 2 is a block diagram showing an optical system according to an embodiment of the present invention.
The light beam that has passed through the photographic lens 1 passes through the quick return mirror 2, the diffusing screen 3, the condenser lens 4, the pentaprism 5, and the eyepiece lens 6 and reaches the eyes of the photographer.
On the other hand, a part of the light beam diffused by the diffusing screen 3 reaches the photometric element 9 through the condenser lens 4, the pentaprism 5, the photometric prism 7, and the photometric lens 8.
[0021]
The quick return mirror 2 is a half mirror that transmits a part of the light beam. The transmitted light beam is bent downward by the sub mirror 10 and passes through the field mask 11, the field lens 12, and the separator lens 13. , And enters the focus detection light-receiving element 14.
[0022]
FIG. 3 is a diagram illustrating the optical system of the focus detection unit 22 in more detail.
The light beam that has passed through the photographic lens 1 is narrowed down to a necessary light beam by the field mask 11, condensed by the field lens 12, and then focused on each light receiving region of the focus detection light receiving element 14 by the separator lens 13. The
This focus detection method is a so-called phase difference detection method, and a secondary image of the object field formed by a pair of separator lenses 13 provided for each focus detection region is applied to the focus detection light receiving element 14. Each of the provided areas is caused to receive light by a pair of CCD sensors, and the focus state is detected from the amount of deviation of their outputs.
[0023]
Further, the area FA1 at the center of the screen is a cross type provided with CCD sensors 1A and 1B for detecting a lateral shift amount and CCD sensors 1C and 1D for detecting a vertical shift amount.
[0024]
FIG. 4 is a diagram showing the division state of the light receiving element 9 in comparison with the object scene.
The light receiving element 9 can measure light by dividing almost the entire surface of the object scene into 10 and can output the respective photometric values BV1 to BV10. Here, the areas of BV6 to BV10 are equal, and BV1 has an area approximately seven times as large as each of these. The shape of BV1 is a shape along a circumference CW having a radius of about 6 mm (about 12 mm in diameter) that serves as an index for center-weighted metering indicated by a dotted line with respect to an aperture size of a 36 mm × 24 mm 35 mm format. . The reason why the circumference of the celestial side is partially cut is to eliminate a high-luminance subject having a high probability of being located on the celestial side such as the sky, but the present invention does not matter whether the celestial side is cut or not. Applicable.
In addition, the focus detection unit 22 can select and detect the focus states of the five areas of the focus detection areas FA1 to FA5 corresponding to BV6 to BV10.
[0025]
FIG. 5A shows a simplified photometric sensitivity distribution with respect to the photographic screen when the photometric values BV1, BV6, BV9, and BV10 of FIG. 4 are used and weighted according to their area ratios are averaged to obtain photometric values. FIG. FIG. 5B is a diagram showing the sensitivity distribution at that time by contour lines.
As shown in FIG. 2, the photometry unit 21 performs photometry using a light beam diffused by the diffusing screen 3, so that the sensitivity does not immediately become zero even at a position deviated from the photometry region. Sensitivity decreases in an inclined form.
[0026]
FIG. 6 (a) simplifies the photometric sensitivity distribution with respect to the photographing screen when the photometric values are obtained by using the photometric areas BV1 and BV6 to BV10 of FIG. FIG. FIG. 6B is a diagram showing the sensitivity distribution at that time by contour lines.
[0027]
FIG. 7A uses the photometric areas BV1 and BV6 to BV10 of FIG. A simplified photometric distribution for the photographic screen when the photometric value is obtained by averaging with a weight such that the photometric sensitivity on the circumference CW of the predetermined radius from the optical axis is equal to the other circumference. It is a figure. FIG. 7B is a diagram showing the sensitivity distribution at that time with contour lines.
The predetermined radius is generally about 6 mm when the shooting screen is a 35 mm film of 36 mm × 24 mm. When averaged by such weighting, the photometric sensitivity distribution becomes the most concentric circle as shown by K in FIG. 7B in the vicinity of the circumference CW of a predetermined radius that is an index of center-weighted photometry. Since the shape of the sensitivity distribution is close, it is a good characteristic for center-weighted photometry.
[0028]
FIG. 8A shows a photometric sensitivity distribution with respect to a photographic screen when the photometric areas BV1, BV6 to BV7, and BV9 to BV10 of FIG. It is the figure which simplified and showed. FIG. 8B shows the sensitivity distribution at that time by contour lines.
In this case, the photometric sensitivity distribution is not concentric from the optical axis X shown in FIG. 8B, and the center of gravity is slightly shifted to X ′ on the BV7 side. When FA2 corresponding to BV7 is selected as the focus detection area, the probability that the position where the main subject exists is shifted to the BV7 side is high. Probability increases.
[0029]
FIG. 9 (a) simplifies the photometric sensitivity distribution with respect to the photographing screen when the photometric values are obtained by using the photometric regions BV1, BV6, and BV8 to BV10 of FIG. FIG. FIG. 9B is a diagram showing the sensitivity distribution at that time with contour lines.
In this case, the photometric sensitivity distribution is not concentric from the optical axis X shown in FIG. 9B, and the center of gravity slightly shifts to X ″ on the BV8 side. Corresponding to BV8 as the focus detection region If FA3 to be selected is selected, the probability that the position where the main subject exists is shifted to the BV8 side is high. Therefore, the probability of proper exposure increases with such sensitivity distribution.
[0030]
FIG. 10 is a flowchart showing a program of the microcomputer 31.
When the release button of a camera (not shown) is pressed halfway, the camera is turned on and this program is executed.
First, in step S101, the setting of the AF / MF switching unit 24 is read. In step S102, it is determined whether the focus adjustment is automatic (AF) or manual (MF). In the case of manual (MF), the following values are set in w6 to w10 in step S103. substitute.
w6 = a, w7 = b, w8 = b, w9 = a, w10 = a (1)
Here, wi (i = 6 to 10) is a weighting number to be multiplied to the photometric area BVi (i = 6 to 10). Further, a is an area ratio of BV6 to BV10 when the area of BV1 is 1, and since the areas of BV6 to BV10 are equal, they are all equal. As shown in FIG. 7, b is a value of a weighting constant that gives weighting so that the photometric sensitivity distribution having a predetermined radius from the optical axis becomes concentric. The value of b can be obtained by simulation from the area ratio or the like, but may be obtained by experiment.
[0031]
If the focus adjustment is automatic (AF), the process proceeds to step S104, the setting of the area selection unit 23 is read, and it is determined which area is selected as the focus detection area. If it is determined in step S105 that the selected area is FA2, the process proceeds to step S106 and the following values are substituted into w6 to w10.
w6 = a, w7 = a, w8 = 0, w9 = a, w10 = a (2)
In this case, the sensitivity distribution of the averaged photometric value is as shown in FIG.
[0032]
Next, when it is determined in step S107 that the selected area is FA3, the process proceeds to step S107, and the following values are substituted into w6 to w10.
w6 = a, w7 = 0, w8 = a, w9 = a, w10 = a (3)
In this case, the sensitivity distribution of the averaged photometric value is as shown in FIG.
[0033]
If the selected area is other than FA2 and FA3, that is, FA1, FA3 to FA5, the process proceeds to step S109, and the following values are substituted into w6 to w10.
w6 = a, w7 = b, w8 = b, w9 = a, w10 = a (4)
In this case, the sensitivity distribution of the averaged photometric value is as shown in FIG.
[0034]
In step S110, focus detection is performed on a selected area among FA1 to FA5.
In step S111, if the focus adjustment is automatic (AF) according to the setting of the AF / MF switching unit 24, the photographic lens 1 is driven to the focus position according to the result of step S110, and is manually (MF). In this case, the photographing lens 1 is not driven, and the focus shift direction is displayed by a display function (not shown).
[0035]
In step S112, photometry of the object scene is performed by the photometry unit 21, and photometric values of BV1 to BV10 are obtained.
In step S113, the final photometric value BVa is calculated by the following equation 1 based on the previously obtained w6 to w10 and the photometric value of each region obtained in step S112.
[0036]
[Expression 1]

[0037]
In general, when a photometric value is calculated, a so-called apex method using a value obtained by converting a photocurrent obtained from the light receiving element 9 in the photometric unit into a logarithm with a base of 2 is used. However, when the photometric value is weighted and averaged in the calculation of Equation 1, it must be performed with a true value proportional to the photocurrent value from the light receiving element 9 instead of the logarithmically compressed photometric value. Therefore, when BVi is a logarithmic value, it is necessary to return to the true value once and perform the operation of Equation 1, and logarithmically compress the calculated value again.
[0038]
In step S114, it is determined whether or not a release button (not shown) is fully pressed. If the release button is fully pressed, the diaphragm 29 and the shutter 30 are controlled based on the obtained photometric value BVa in step S115. If the film is exposed and not fully depressed, the process proceeds directly to step S116.
In step S116, it is determined whether or not a predetermined time has elapsed after releasing the half-press of the release by a half-press timer. If the release is half-pressed or if the timer is within the predetermined time, the process returns to step S101. The process is repeated, and if the timer has expired, the program ends.
[0039]
According to this embodiment, there are various effects as follows.
(1) Even in a photometric device using a photometric element having a complicated divided shape, the photometric sensitivity distribution is close to a concentric circle in the center-weighted photometric mode.
(2) Even in the case of a photometric element having a split shape in which the spot photometric area penetrates a predetermined radius, the photometric sensitivity distribution is close to a concentric circle.
(3) A photometric value having an optimal photometric sensitivity distribution can be obtained according to the selected focus detection region.
(4) When a focus detection area is provided in an area corresponding to the spot photometry area, a photometric value having an optimal photometric sensitivity distribution can be obtained.
(5) A photometric value having an optimal photometric sensitivity distribution can be obtained by lowering the weight of the spot photometric region corresponding to the focus detection region that is not selected.
(6) When focus adjustment is performed automatically / manually, a photometric value having an optimal photometric sensitivity distribution can be obtained.
[0040]
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the equivalent scope of the present invention.
For example, the division state of the division photometry is not limited to that shown in FIG. 4, but may be a matrix photometry element as shown in FIG. In this case, for the photometric area M indicated by diagonal lines, the photometric sensitivity on the circumference of a predetermined radius from the optical axis indicated by L in the figure is averaged by a weight that is equal to that on other circumferences. To obtain the photometric value. When averaged by such weighting, the photometric sensitivity distribution is most concentrically around the circumference of a predetermined radius, which is a good characteristic for center-weighted photometry.
[0041]
【The invention's effect】
As described above in detail, according to the present invention, even when a photometric element that is also used for another photometric mode is used, the shape of the finder index and the actual photometric sensitivity distribution are the same, and photometry with little photometric error is achieved. An apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of a photometric device for a camera according to the present invention.
FIG. 2 is a diagram showing an optical system of a photometric device according to the present embodiment.
FIG. 3 is a diagram illustrating a configuration of a focus detection unit of the photometric device according to the present embodiment.
FIG. 4 is a diagram illustrating a split state of split photometry of the photometric device according to the present embodiment.
FIG. 5 is a diagram showing a photometric sensitivity distribution of the photometric device according to the present embodiment.
FIG. 6 is a diagram showing a photometric sensitivity distribution of the photometric device according to the present embodiment.
FIG. 7 is a diagram showing a photometric sensitivity distribution of the photometric device according to the present embodiment.
FIG. 8 is a diagram showing a photometric sensitivity distribution of the photometric device according to the present embodiment.
FIG. 9 is a diagram showing a photometric sensitivity distribution of the photometric device according to the present embodiment.
FIG. 10 is a flowchart showing an algorithm of the photometric device according to the present embodiment.
FIG. 11 is a diagram illustrating a split state of split photometry of a photometric device according to another embodiment.
FIG. 12 is a diagram illustrating an example of a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shooting lens 2 Quick return mirror 3 Diffusion screen 4 Condenser lens 5 Penta prism 6 Eyepiece lens 7 Photometric prism 8 Photometric lens 9 Light receiving element 10 Color measuring light receiving element 11 Field mask 12 Field lens 13 Separator lens 14 Light reception for focus detection Element 21 Photometry unit 22 Focus detection unit 23 Area selection unit 24 AF / MF switching unit 25 Lens drive unit 26 Weight determination unit 27 Exposure calculation unit 28 Exposure control unit 29 Aperture 30 Shutter 31 Microprocessor

Claims (5)

An index indicating the central metering range set for the object field,
The object field is a plurality of areas including a central photometry area positioned corresponding to the index, and a spot photometry area located on a line corresponding to the outer shape of the index and extending to the inside and outside of the index A metering unit that divides and measures the light and outputs the metered value of each area;
As the outer shape of the photometric sensitivity distribution of the photometry unit becomes substantially the same as the shape of the indicators, by adding weighted photometric values of the spot metering area photometric value of the central photometric region, said central metering photometric device comprising a photometric value calculation unit that calculates a photometric value of the region. The photometric device according to claim 1,
Among the object scene, and the focus detection unit for detecting the focus state of the plurality of focus detection area including the area corresponding to the spot metering area,
An area selector that selects one of the plurality of focus detection areas;
The photometric value calculation unit, wherein when the focus detection area selected by the area selecting unit is one corresponding to the spot metering area, the central photometric region by increasing the weighting for the photometric value of the spot metering area A photometric device which calculates a photometric value of The photometric device according to claim 2 ,
The photometric value calculation unit, the photometric apparatus characterized by lower than the weight of the spot metering area corresponding weights of the spot metering area corresponding to the focus detection area is not selected, the selected focus detection area was . In the photometric device according to claim 2 or claim 3 ,
A focus adjustment selection unit for selecting whether to automatically or manually adjust the focus of the photographing lens;
The photometric value calculation unit, based on an output of the focus adjustment selecting unit, the photometric apparatus and changes the weight. A camera comprising the photometric device according to any one of claims 1 to 4 .

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