JP3703153B2 - Focus detection device - Google Patents

Description

となる。
【００４５】
これを用い、補正焦点検出信号Ｄ_C （Ｌ）を演算している。
【００４６】
図３は（７）式の関数を縦軸に補正値Ｃ（ｘ）、横軸にｘをとって描いた説明図である。
【００４７】
図中、実線がｒ＝１の場合、破線がｒ＝２の場合を示す。図より明らかなように、ｒの値の違いによってｘの大きい領域では補正値の値が大きく異なり、ｒを適切に選択することにより、各レンズに応じた最適な補正値が求められる。
【００４８】
本実施例においては、撮影レンズ本体７１はそのＲＯＭ７４内にｒの値に関し２つのタイプのどちらに属するかの情報を保持しておく必要があるが、たかだか１ビットの情報でよく、新たな補正値を持つことに比べれば、記憶容量に対する負担は軽微である。
【００４９】
また、撮影レンズＲＯＭ７４内に前述の補正値Ｃ（０），Ｃ（Ｌ´）の他に撮影レンズの固有の情報、例えば焦点距離、開放絞り値、瞳位置、フォーカスレンズの敏感度等に関する情報が記憶されている場合には、これらの情報からｒのタイプを判別してもよい。
【００５０】
例えば、開放絞り値が小さく（即ち明るく）瞳位置が遠い撮影レンズでは焦点検出系に影響を及ぼす画角変化に伴う収差変動が比較的少ないと判断し、ｒを１とし、また焦点距離の短い画角の大きな撮影レンズは収差変動が大きくなる可能性があるとして、ｒを２とする等の判定を行なう手段を設けてもよい。更に、ｒの値として１，２だけでなく1/2,1/4 等を採用してもよい。
【００５１】
実施例１においては、近似関数のタイプを２つとしたが、更に近似精度を高めるためにタイプ数を増やすこともできる。例えば、補正値Ｃ（ｘ）を近似する関数として以下の４つを仮定するようにしてもよい。
【００５２】
【数２】

これらの近似関数のうち、タイプ１，タイプ２の係数は既知の補正値であるＣ（ｘ），Ｃ（Ｌ´）を用いてそれぞれ次のように表わせる。
【００５３】
【数３】

また、タイプ３，タイプ４はタイプ１，タイプ２をｘ＝Ｌ´で接続したものであるが、接続の仕方としてタイプ１，タイプ２を単純に接続する方法と、なめらかに接続する方法の２つが考えられる。簡単な計算により係数はそれぞれ次のように表わされる。
【００５４】
単純に接続する場合は各近似関数の係数を独立に決定し、
【００５５】
【数４】

なめらかに接続する場合はｘ＝Ｌ´で１次微分が連続となるように係数を決定し、
【００５６】
【数５】

となる。
【００５７】
タイプ１，タイプ２の補正値Ｃ（ｘ）はグラフに示すと図３の実線，破線と同様になる。図４，図５は単純に接続した場合のタイプ３，タイプ４の補正値Ｃ（ｘ）を、また図６，図７はなめらかに接続した場合のタイプ３，タイプ４の補正値Ｃ（ｘ）をそれぞれ図示した説明図である。
【００５８】
本実施例においては４つのタイプを区別するための情報が必要となるが、情報量としては２ビット相当にすぎず、実施例１と同様に必要とする記憶容量を著しく増大させる原因とはならない。また実施例１の説明で述べたとおり、タイプを区別するための特別の情報を持たず、撮影レンズ本体７１内のＲＯＭ７４内の他の情報から４つのタイプを判定するようにしてもよい。
【００５９】
近似関数としては以上の実施例に用いられているものの他に、指数関数や対数関数、三角関数、或いはそれらを接続したもの等、種々のものを用いることが可能である。また以上の実施例においては、既知の補正値の数が２の場合を例に説明を行なったが、３以上であってももちろんよく、その数に応じて近似関数も適宜適当なものを選択することができる。
【００６０】
図８は本発明の実施例２の焦点検出部分を示す要部概略図である。
【００６１】
本実施例における２次光学系の構成は図１１と同様であるが、周辺視野が左右各々開口部３１−２，３１−３，３１−４，３１−５と２つずつになり、又センサー列が３５−４ａ，３５−４ｂ，３５−４ｃ，３５−４ｄと増えている。焦点検出領域の数が増えても、前述と同様の方法により本発明は適用できる。
【００６２】
【発明の効果】
本発明によれば以上のように各要素を設定することにより、多く検出領域（測距領域）での焦点検出信号を撮影レンズ毎の補正値を用いて補正して求める際に適切なる演算処理により簡易に求めることができ、高密度の記憶容量の記憶素子を用いずに高精度な焦点検出が可能な焦点検出装置を達成することができる。
【図面の簡単な説明】
【図１】 本発明の実施例１の要部概略図
【図２】 図１の測距範囲の説明図
【図３】 本発明に係る補正値と測距範囲とを示す説明図
【図４】 本発明に係る補正値と測距範囲とを示す説明図
【図５】 本発明に係る補正値と測距範囲とを示す説明図
【図６】 本発明に係る補正値と測距範囲とを示す説明図
【図７】 本発明に係る補正値と測距範囲とを示す説明図
【図８】 本発明の実施例２の一部分の説明図
【図９】 従来の像ずれ方式の焦点検出装置の要部概略図
【図１０】

【図１１】 従来の像ずれ方式の焦点検出装置の要部概略図
【図１２】 図９の一部分の説明図
【符号の説明】
７１ 撮影レンズ本体
７２ 撮影レンズ
７３ 駆動装置
７４ 記憶装置
７５ レンズ制御手段
７６ カメラ本体
７７ 焦点板
８０ 焦点検出手段
８１ 制御手段
８４ 接点[0001]
[Industrial application fields]
The present invention relates to a focus detection apparatus suitable for a photographic camera, a video camera, and the like, and in particular, divides a pupil of an objective lens into a plurality of regions, and uses a light beam that passes through each region to emit light amounts related to a plurality of subject images (object images). The present invention relates to a focus detection device suitable for detecting a focus state of an objective lens with respect to a plurality of areas in an imaging range by forming a distribution and obtaining a relative positional relationship between the plurality of light quantity distributions. is there.
[0002]
[Prior art]
Conventionally, there is a so-called image shift method as a light receiving type focus detection method using a light beam that has passed through an objective lens. This image shift method is proposed in, for example, Japanese Patent Application Laid-Open Nos. 59-10731 and 59-107313.
[0003]
FIG. 9 is a schematic diagram of an optical system of a focus detection apparatus using a conventional image shift method.
[0004]
In the figure, reference numeral 61 denotes an objective lens, and 62 denotes a field mask, which is disposed in the vicinity of the intended imaging plane of the objective lens 61. A field lens 63 is disposed in the vicinity of the planned image plane. Reference numeral 64 denotes a secondary optical system, which includes two lenses 64-1 and 64-2 arranged symmetrically with respect to the optical axis of the objective lens 61. A light receiving means 65 has two light receiving element rows 65-1 and 65-2 disposed on the rear side corresponding to the two lenses 64-1 and 64-2. Reference numeral 66 denotes a stop, which has two openings 66-1 and 66-2 disposed in front of the two lenses 64-1 and 64-2, respectively. Reference numeral 67 denotes an exit pupil of the objective lens 61, which is composed of two divided regions 67-1 and 67-2.
[0005]
The field lens 63 has an effect of forming the openings 66-1 and 66-2 in the areas 67-1 and 67-2 of the exit pupil 67, and transmits through the areas 67-1 and 67-2. The luminous fluxes form a light quantity distribution on the light receiving element rows 65-1 and 65-2, respectively.
[0006]
In the focus detection apparatus shown in FIG. 9, when the imaging point of the objective lens 61 is on the front side of the scheduled imaging surface, the object images formed on the two light receiving element rows 65-1 and 65-2 are related. When the light quantity distributions are close to each other and the imaging point of the objective lens 61 is on the rear side of the planned imaging surface, the light quantities formed on the two light receiving element rows 65-1 and 65-2, respectively. Distributions are separated from each other. In addition, the amount of deviation of the light amount distribution formed on each of the two light receiving element rows 65-1 and 65-2 has a certain functional relationship with the amount of defocus of the objective lens 61. When calculated, the direction and amount of defocus of the objective lens 61 can be detected.
[0007]
The focus detection apparatus shown in FIG. 9 performs distance measurement with respect to a subject that exists in the approximate center of the subject range photographed by the objective lens.
[0008]
On the other hand, the present applicant has previously proposed in Japanese Patent Application No. 62-279835 a focus detection device capable of detecting a focus at a distance measuring point other than the center of the photographing range.
[0009]
FIG. 10 is a schematic view of an optical system of a focus detection apparatus for a plurality of distance measuring points proposed in Japanese Patent Application No. 62-279835. In the figure, 71 is a field mask, 72 is a field lens, 73 is a stop having two apertures 73-1 and 73-2, 74 is a secondary optical system comprising two lenses 74-1 and 74-2, and 75 is Each sensor is shown. Note that the objective lens 61 shown in FIG. 9 is omitted.
[0010]
In the figure, the field mask 71 has a plurality of openings 71 a to 71 e corresponding to a plurality of fields to be measured, and a plurality of light beams restricted by the field mask 71 are formed by the secondary optical system 74. A plurality of pairs of sensor arrays 75a1 and 75a2, 75b1 and 75b2, 75c1 and 75c2, 75d1 and 75d2, and 75e1 and 75e2 are provided as sensors 75 so as to receive the light quantity distribution of the pair.
[0011]
In the figure, distance measurement is performed in five areas as a whole at the center of the photographing screen and at four places on both sides thereof. In this way, it is very important to be able to detect the focus in a plurality of areas in the shooting screen when applied to a camera.
[0012]
In the focus detection apparatus shown in FIG. 10, the direction in which the two light quantity distributions on the sensor move relative to each other depending on the focus state of the objective lens is the vertical direction. Only a distance can be measured, and an object having a change in the light amount distribution only in a direction perpendicular thereto, for example, a monochrome edge pattern having a vertical line as a boundary cannot be measured.
[0013]
For this reason, the applicant of the present invention can measure the distance even in the case of Japanese Patent Application No. 63-274940, even for an object whose light amount distribution changes only in one direction up and down or left and right near the center of the photographing range. A focus detection apparatus that can measure a distance at a plurality of points other than the vicinity of the center of the imaging range is proposed.
[0014]
FIG. 11 is a schematic view of the main part of the focus detection apparatus proposed in Japanese Patent Application No. 63-274940.
[0015]
In the figure, reference numeral 31 denotes a field mask, which intersects substantially the center of a photographing screen by an objective lens (photographing lens) (not shown), for example, a cruciform opening 31-1 and vertically long openings 31-2 on both sides. , 31-3. Reference numeral 32 denotes a field lens, which corresponds to the three openings 31-1, 31-2, 31-3 of the field mask 31, and has three regions 32-1, 32-2, 32-- each having predetermined optical characteristics. It consists of three. Reference numeral 33 denotes an aperture, with a central portion including four openings 33-1a, 33-1b, 33-1c, and 33-1d, one pair vertically and horizontally, and a pair of two openings on the left and right peripheral portions. Portions 33-2a and 33-2b and openings 33-3a and 33-3b are respectively provided.
[0016]
The areas 32-1, 32-2, and 32-3 of the field lens 32 have openings 33-1, 33-2, and 33-3 that are paired with a diaphragm 33, respectively, in the vicinity of the exit pupil of a photographing lens (not shown). Has an effect of forming an image. Reference numeral 34 denotes a secondary optical system, which has four pairs of secondary imaging lenses as a whole.
[0017]
That is, as a whole, there are eight secondary imaging lenses 34-1a, 34-1b, 34-1c, 34-1d, 34-2a, 34-2b, 34-3a, 34-3b. It arrange | positions in the back corresponding to each opening part.
[0018]
A light receiving element array (sensor) 35 has four pairs of sensor arrays as a whole. That is, as a whole, there are eight sensor rows 35-1a, 35-1b, 35-1c, 35-1d, 35-2a, 35-2b, 35-3a, 35-3b, corresponding to the secondary imaging lens. Then, it is arranged to receive the image.
[0019]
FIG. 12 is an explanatory view showing an image region formed on the surface of the sensor 35 of FIG. Regions 36-1 a, 36-1 b, 36-1 c, and 36-1 d are image regions of the central opening 31-1 of the field mask 31, and the light beam that has passed through the central portion 32-1 of the field lens 32 is After being restricted by the openings 33-1a, 33-1b, 33-1c, and 33-1d, the surface of the sensor 35 is provided by the secondary imaging lenses 34-1a, 34-1b, 34-1c, and 34-1d at the rear thereof. Each of the states formed above is shown.
[0020]
Reference numerals 36-2a and 36-2b denote image regions of the opening 31-2 around the field mask 31, and the light beam transmitted through the periphery 32-2 of the field lens 32 is the openings 33-2a and 33-2a of the stop 33. After being regulated by 33-2b, the secondary imaging lenses 34-2a and 34-2b behind it are formed on the sensor 35.
[0021]
Similarly, 36-3a and 36-3b are image regions of the opening 31-3 around the field mask 31, and the light beam that has passed through the periphery 32-3 of the field lens 32 is the opening 33-3a, 3B shows image areas formed on the surface of the sensor 35 by secondary imaging lenses 34-3a and 34-3b behind them after being regulated by 33-3b.
[0022]
The focus detection principle of the focus detection apparatus shown in FIG. 11 is to detect the relative position of the paired image in the sensor array direction as in the conventional case.
[0023]
By adopting the configuration described above, even an object whose light intensity distribution changes only in one direction, up and down or right and left, is measured near the center of the range photographed or observed by an objective lens (not shown). It is possible to measure the distance, and it is also possible to measure an object at a position corresponding to the openings 31-2 and 31-3 around the field mask 31 other than the center.
[0024]
In general, interchangeable photographic lenses such as single-lens reflex cameras have inherent aberrations, and their amounts and correction tendencies differ. Even with the same type of photographic lens, there are individual differences due to manufacturing errors during manufacture. For this reason, when the above-described focus detection device is used for a camera such as a single-lens reflex camera in which a photographic lens can be replaced, drive control of the photographic lens (focusing lens) is performed based on a focus detection signal directly obtained by the focus detection device. If this is done, a proper focus state may not be obtained.
[0025]
In order to solve such a problem, a correction value C specific to the focus detection signal is used for each photographing lens, and for example, a focus detection signal D representing an out-of-focus amount is expressed as D _C = D−c.・ (1)
There has been proposed a focus detection apparatus that performs correction control according to the above and performs drive control of the focusing lens based on the corrected focus detection signal D _C obtained at this time.
[0026]
[Problems to be solved by the invention]
The correction value C specific to each photographic lens generally depends on the position of the detection area (ranging area) of the focus detection device. For this reason, when there are detection areas other than the centers as shown in FIGS. 10 and 11, it is necessary to have correction values corresponding to the respective detection areas. However, if there are a large number of assumed detection areas, a storage element with a large storage capacity is required to have correction values for all the detection areas on the photographing lens side or the camera body side, and calculation of the focus detection signal There arises a problem that the input / output control of the correction value becomes complicated.
[0027]
On the other hand, when there is already a photographing system such as a single-lens reflex camera and an interchangeable lens that operates only on a certain position and number of detection areas, a focus detection device having a different detection area position and number is mounted. The camera cannot be used as is in this system. In order to be usable, all of the newly required correction values must be provided on the camera body side, and similarly a problem arises that a storage element having a large storage capacity is required.
[0028]
The present invention can easily obtain a focus detection signal in a large number of detection areas (ranging areas) by correcting using the correction value for each photographing lens by an appropriate calculation process, and has a high storage capacity. An object of the present invention is to provide a focus detection apparatus capable of detecting a focus with high accuracy without using a memory element.
[0029]
[Means for Solving the Problems]
The focus detection apparatus according to the first aspect of the present invention includes a focus detection unit disposed on the image plane side of the photographing lens,
When obtaining the in-focus state of the photographic lens for a plurality of ranging areas in the photographic range using the focus detection means,
The focus detection unit uses at least one specific information of the photographing lens and a value related to a correction value of the photographing lens corresponding to at least two predetermined ranging areas among a plurality of ranging areas. Control means for determining an approximate expression type and coefficient, calculating a correction value using the determined approximate expression type and coefficient, and correcting the focus detection signal obtained by the focus detection means with the calculated correction value It is characterized by having.
[0030]
According to a second aspect of the present invention, in the first aspect of the invention, the focus detection unit uses a light beam that has passed through different regions of the pupil of the photographing lens to form a plurality of light quantity distributions related to a subject image, Light receiving means for detecting the relative positional relationship of a plurality of light quantity distributions, and the secondary optical system has a plurality of pairs of secondary imaging lenses.
According to a third aspect of the present invention, there is provided a camera system including the focus detection apparatus according to the first or second aspect.
[0031]
【Example】
FIG. 1 is a schematic diagram of a main part of Embodiment 1 of the present invention, and FIG. 2 is an enlarged explanatory view of a part of FIG.
[0032]
In the figure, reference numeral 71 denotes a photographic lens body, and inside the photographic lens 72 and a lens system constituting the photographic lens 72, all or a part of focusing lenses are moved, and driving for adjusting the focus state of the photographic lens 72 is shown. A device 73 and a storage device 74 such as a ROM and a lens control means 75 for controlling them are provided.
[0033]
Reference numeral 76 denotes a camera body, a finder system including a focusing plate 77, a pentaprism 78, and an eyepiece 79 on which an object image is formed by the photographic lens 72, a focus detection system including a focus detection means 80 and its control means 81, and a photographic lens. A main mirror 82 for guiding the light from 72 to the finder system, and a sub mirror 83 for guiding the light from the photographing lens 72 to the focus detection means 80 are included. The photographing lens main body 71 and the camera main body 76 have a contact 84, and when they are attached to each other, information is communicated and power is supplied through them.
[0034]
The focus detection means 80 of this embodiment has the same configuration requirements as shown in FIG. 11, and the distance measurement principle is the same.
[0035]
FIG. 2 shows the focus detection area on the focusing screen 77 in FIG. 1 when the focus detection means 80 shown in FIG. 11 is adopted. In correspondence with the opening shape of the field mask 31 in FIG. 11 or the arrangement of the sensors 35, a central cross area 85 and a peripheral rectangular area 86 separated from the center by L are focus detection areas.
[0036]
On the other hand, the photographing lens main body 71 has correction values C (O) and C (L ′) in the focus detection signal D for the central region and the peripheral region separated from the center by a distance L ′.
[0037]
In the imaging apparatus of FIG. 1, for example, when a central area is selected in advance as a focus detection area, the focus detection system is activated by pressing the first stage of a shutter button (not shown), and the center area at that time is activated. An amount representing the focus state of the photographic lens 72, for example, an out-of-focus amount D (O) is detected. Subsequently, the correction value C (O) for the central focus detection area stored in the ROM 74 of the photographic lens body 71 is read into the focus detection system control means 81 via the contact 84.
[0038]
And D _C (O) = D (O) −C (O) (2)
The final corrected focus detection signal D _C (O) is obtained by the above calculation. Based on this value, the focusing lens is driven by the driving device 73 of the photographic lens body 71 to adjust the focus state.
[0039]
Similarly, an out-of-focus amount D (L) is detected for a peripheral focus detection region that is separated from the center by a distance L, and L = L ′ (3)
If so, the correction value C (L ′) in the ROM 74 of the photographing lens body 71 is used as it is, and the correction focus detection signal D _C (L) is D _C (L) = D (L) −C (L ′). .... (4)
As required.
[0040]
In contrast,
L ≠ L ′ (5)
In this case, in the present invention, the correction value C (L) is obtained by calculation as follows.
[0041]
That is, the correction value C (X) for the focus detection region that is separated from the center by x is a function of x.
C (x) = ax ^r + b (6)
It is said that it is expressed by.
[0042]
Here, r is a constant that can take two values of 1 or 2. By obtaining information indicating whether the two correction values C (0), C (L ′) and r are either 1 or 2 from the R0M 74 of the photographic lens body 71, the coefficients a and b of the equation (6) are obtained. Seeking.
[0043]
From this, the correction value C (x) is:
[Expression 1]

It becomes.
[0045]
Using this, the corrected focus detection signal D _C (L) is calculated.
[0046]
FIG. 3 is an explanatory diagram depicting the function of equation (7) with the correction value C (x) on the vertical axis and x on the horizontal axis.
[0047]
In the figure, the solid line indicates r = 1 and the broken line indicates r = 2. As is clear from the figure, the correction value varies greatly in the region where x is large depending on the difference in r, and the optimum correction value corresponding to each lens can be obtained by appropriately selecting r.
[0048]
In this embodiment, the photographing lens main body 71 needs to store information on which of the two types is associated with the value of r in the ROM 74, but it may be at most 1-bit information, and a new correction is made. Compared to having a value, the burden on the storage capacity is light.
[0049]
In addition to the correction values C (0) and C (L ′) described above in the photographic lens ROM 74, information specific to the photographic lens, such as focal length, open aperture value, pupil position, sensitivity of the focus lens, etc. May be determined from these pieces of information.
[0050]
For example, in a photographing lens with a small open aperture value (that is, bright) and a far pupil position, it is determined that there is a relatively small aberration variation due to a change in the angle of view that affects the focus detection system, r is set to 1, and the focal length is short. A photographing lens having a large angle of view may be provided with a means for performing a determination such as setting r to 2 because there is a possibility that the aberration fluctuation will increase. Furthermore, not only 1, 2 but also 1/2, 1/4, etc. may be adopted as the value of r.
[0051]
In the first embodiment, the number of types of approximate functions is two. However, the number of types can be increased to further increase the accuracy of approximation. For example, the following four functions may be assumed as functions approximating the correction value C (x).
[0052]
[Expression 2]

Of these approximate functions, the coefficients of type 1 and type 2 can be expressed as follows using known correction values C (x) and C (L ′), respectively.
[0053]
[Equation 3]

Type 3 and type 4 are obtained by connecting type 1 and type 2 with x = L ′. As a connection method, type 1 and type 2 are simply connected and smooth connection 2 One can be considered. The coefficients are expressed as follows by simple calculation.
[0054]
When connecting simply, determine the coefficient of each approximation function independently,
[0055]
[Expression 4]

When connecting smoothly, the coefficient is determined so that the first derivative is continuous at x = L ′,
[0056]
[Equation 5]

It becomes.
[0057]
The correction values C (x) of type 1 and type 2 are the same as the solid and broken lines in FIG. 4 and 5 show correction values C (x) of type 3 and type 4 when simply connected, and FIGS. 6 and 7 show correction values C (x of type 3 and type 4 when connected smoothly. ).
[0058]
In this embodiment, information for distinguishing the four types is required. However, the amount of information is only 2 bits, and it does not cause a significant increase in the required storage capacity as in the first embodiment. . Further, as described in the description of the first embodiment, the four types may be determined from other information in the ROM 74 in the photographing lens main body 71 without having special information for distinguishing the types.
[0059]
As an approximate function, various functions such as an exponential function, a logarithmic function, a trigonometric function, or a combination thereof can be used in addition to the functions used in the above embodiments. In the above embodiments, the case where the number of known correction values is 2 has been described as an example. However, the number of known correction values may be 3 or more, and an approximate function is appropriately selected according to the number. can do.
[0060]
FIG. 8 is a schematic view showing the main part of a focus detection portion according to the second embodiment of the present invention.
[0061]
The configuration of the secondary optical system in this embodiment is the same as that shown in FIG. 11, but the peripheral visual field has two openings 31-2, 31-3, 31-4, and 31-5. The columns are increased to 35-4a, 35-4b, 35-4c, and 35-4d. Even if the number of focus detection areas increases, the present invention can be applied by the same method as described above.
[0062]
【The invention's effect】
According to the present invention, by setting each element as described above, it is possible to perform an appropriate calculation process when correcting the focus detection signals in many detection areas (ranging areas) using correction values for each photographing lens. Thus, it is possible to achieve a focus detection device that can be obtained easily and can perform focus detection with high accuracy without using a storage element having a high density storage capacity.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a main part of Embodiment 1 of the present invention. FIG. 2 is an explanatory diagram of a distance measurement range in FIG. 1. FIG. FIG. 5 is an explanatory diagram showing a correction value and a distance measurement range according to the present invention. FIG. 5 is an explanatory diagram showing a correction value and a distance measurement range according to the present invention. FIG. 7 is an explanatory view showing a correction value and a distance measurement range according to the present invention. FIG. 8 is a partial explanatory view of Embodiment 2 of the present invention. FIG. 9 is a conventional image shift method focus detection. Schematic diagram of the main part of the device [Figure 10]

11 is a schematic diagram of the main part of a conventional image shift type focus detection apparatus. FIG. 12 is an explanatory view of a part of FIG.
71 photographic lens main body 72 photographic lens 73 drive device 74 storage device 75 lens control means 76 camera main body 77 focusing screen 80 focus detection means 81 control means 84 contact point

Claims (3)

Place focus detection means on the image plane side of the photographic lens,
When obtaining the in-focus state of the photographic lens for a plurality of ranging areas in the photographic range using the focus detection means,
The focus detection unit uses at least one specific information of the photographing lens and a value related to a correction value of the photographing lens corresponding to at least two predetermined ranging areas among a plurality of ranging areas. Control means for determining an approximate expression type and coefficient, calculating a correction value using the determined approximate expression type and coefficient, and correcting the focus detection signal obtained by the focus detection means with the calculated correction value focus detecting apparatus characterized by having a.     The focus detection means detects a relative optical positional relationship between a secondary optical system that forms a plurality of light quantity distributions related to a subject image using light beams that have passed through different areas of the pupil of the photographing lens, and the plurality of light quantity distributions. The focus detection apparatus according to claim 1, further comprising: a light receiving unit, wherein the secondary optical system includes a plurality of pairs of secondary imaging lenses. A camera system comprising the focus detection device according to claim 1 .

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