JPH06250251A - Photometry device - Google Patents

Abstract

PURPOSE:To provide a photometry system capable of performing photometry without necessitating a window opening for photometry, having high degree of freedom in respect of a design of a camera body and suppressing the occurrence of parallax between an image pickup plane and a photometric area. CONSTITUTION:The device is provided with an objective lens for photographing 3 installed separate from an objective lens for finder, 21 brightness diaphragm 4 installed on a side nearer to an image than the incident plane of the objective lens for photographing 3, a measuring light guiding means 9 installed on a side nearer to the object than the brightness diaphragm 4 and a light receiving means 10 for receiving the light transmitted through the objective lens for photographing 3 and not transmitted through the brightness diaphragm 4 with the measuring light guiding means 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photometric device for a camera.

[0002]

2. Description of the Related Art Generally, in a lens shutter type camera, which is a so-called compact camera, a shutter function is integrally added to an aperture stop so that the size and weight can be reduced and the cost can be reduced. Has been achieved. For this reason, in the conventional lens shutter type camera configured by adopting such a format, there is no luminous flux between the aperture stop and the image pickup surface such as a film except when the exposure is performed. In the case of a lens shutter type camera, its photographing optical system and finder optical system are usually configured independently, and its photometric optical system is also configured independently of the photographing optical system.

Here, the role of the photometric device including the photometric optical system in the camera is as follows: (a) exposure time setting, (b) exposure NA setting, and (c) strobe light emission determination / light emission amount. There are settings, etc. Then, some programs set these roles in a well-balanced manner by a preset program, and some programs determine flash emission from the distribution of brightness of the main subject and background.

[0004]

However, in this type of camera, when the taking optical system and the photometric optical system are independent as described above, parallax occurs, and photometry is performed depending on the taking distance. The relationship between the part that is being photographed and the part that is being photographed will change.

Here, FIG. 13 shows a schematic configuration of a camera in which a photographing optical system and a photometric optical system are independent. That is, in FIG. 13, reference numerals 101 and 102 denote photographing lenses and films forming a photographing optical system, an image pickup surface such as a CCD, and reference numerals 111 and 112 denote photometric lenses and photometric means constituting a photometric optical system. Is the light receiving surface of.

That is, in the camera shown in FIG. 13 in which the photographing optical system and the photometric optical system are independently configured, the photographing range 122 (shown by the solid line) at a specific subject position (reference subject position) 121a. And the photometric range 123 (shown by the dotted line) match, but other subject positions 12
In 1b, the shooting range 122 and the photometric range 123 do not match.

FIG. 13 shows the case where the photometric range 123 near the entire screen is provided. However, in photometry only near the center, the photometric range 123 deviates from the vicinity of the center as the distance from the reference object position 121a increases. become. Further, when a position not intended for photometry is included in the photometry range 123 and there is a strong light source at that position, proper exposure cannot be naturally performed. Further, it also has various problems that a window opening for photometry in the photometric optical system is required on the front surface, which becomes a constraint condition in the design of the camera body.

The present invention has been made in order to solve the above-mentioned conventional problems.
It enables photometry without the need for a window for photometry, has a high degree of freedom in the design of the camera body, and provides a photometric system in which parallax is unlikely to occur between the imaging surface and the photometric range. It is to provide a photometric device for this type of camera.

[0009]

In order to achieve the above-mentioned object, a photometric device for a camera according to the present invention comprises a photographic objective lens provided separately from a finder objective lens, and a photographic objective lens. An aperture stop located closer to the image side than the entrance surface and a measurement beam that is placed closer to the subject than the aperture stop and guides a part of the light flux that has passed through the objective lens for shooting out of the optical path for shooting. And a light receiving means for receiving the light beam that has deviated from the optical path for photographing by the measuring light introducing means.

FIG. 1 shows a basic structure for photometry of the central portion of the photographing range in the photometric device according to the present invention.

In the apparatus configuration shown in FIG. 1, an axial light flux 1 emitted from a subject 2 on the optical axis is in front of a photographing objective lens (hereinafter referred to as a photographing lens front) 3 (brightness of the photographing lens). (A portion closer to the subject than the aperture stop), the size of the light flux is determined by the brightness stop 4, and passes through a rear portion 5 of the taking lens (a portion closer to the image side than the aperture stop of the taking lens). An image is formed on the imaging surface 6 such as a film or a CCD.

The opening of the front portion 3 of the photographing lens is formed larger than the range in which the on-axis light beam 1 passes, for example, to allow the off-axis light beam 7 to pass therethrough, and emits the subject 2 on the optical axis. A light beam 8 that passes through a region other than the passing area of the axial light beam 1 at the photographing lens front portion 3 is reflected by the reflecting member 9 on the side of the photographing lens front portion 3 of the aperture stop 4 and is incident on the light receiving means 10 for photometry. It

It is desirable that the light receiving means 10 be near the image forming position of the light beam 8, and this enables photometry with a strong spot property. Also, when changing the photometric weight depending on the position on the screen (for example, center-weighted photometry, multipoint photometry,
What is called evaluation light) can be easily dealt with by dividing the light receiving means 10 or changing the light receiving sensitivity depending on the light receiving position.

Further, it is desirable that the conjugate positions of the light receiving means 10 and the image pickup surface 6 are substantially the same in conjunction with the focusing operation of the taking lens, and thus the light receiving means 1 is always in operation.
It is possible to form an image of a subject at a distance substantially the same as that of the imaging surface 6 on 0.

Further, it is desirable that the photometric operation by the light receiving means 10 is started after the focusing operation of the taking lens is started. Thus, the photometric operation is started after the focusing operation of the taking lens is almost finished. When performing the measurement, photometry is performed in a state in which a subject having a distance substantially the same as the image pickup surface 6 is imaged on the light receiving means 10, and proper exposure is given to the set screen position. You can

FIG. 2 shows an example of a flowchart of the operation of the lens shutter type camera having the above-mentioned basic structure.

According to FIG. 2, when the power of the camera is turned on (step 1) and the release is pushed to the first stage (step 2), first, the object distance is set by a range finder (not shown) or the like (step 3). ), The photographing lens is adjusted for focusing (step 4), and then the photometry is performed (step 5), and then the flash emission determination (step 6) is performed. Based on the determination result, the flash standby instruction (step 7) and / Or exposure time, exposure Fno (aperture value) is set (step
8) and the focusing is readjusted (step 9), and then the strobe is on standby (step 11: Yes), provided that the release is pushed down to the second step (step 10).
In step s), the desired exposure and stroboscopic light emission are performed under the set conditions (step 12), and when the strobe is not in standby (No in step 11), similarly, the desired exposure is performed according to the set conditions. (Step 12 ').

In this case, "re-adjustment of focusing" in step 9 is performed to improve the stopping accuracy of the focusing lens or to adjust the object moved a little during focusing operation or photometry. This means that step 9 can be omitted depending on the specifications of the camera.

Further, the flow chart according to the example of FIG. 2 is based on the assumption of so-called focus lock and AE lock, and if the release is only one stage according to the camera specifications, the step 10 is unnecessary.

Furthermore, depending on the flash function of the camera,
Although each step 6, 7, 11 has a different format, it does not depart from the gist of the present invention.

In the basic structure of the present invention, it is desirable to dispose an optical element such as a Fresnel lens or a diffractive optical element on the photometric optical path, and these optical elements are macroscopically planar. Can have power. N · sin (i) ≠ N ′ · sin (i ′) [In case of refraction] i ≠ −i ′ [In case of reflection] (1) However, in the formula (1), i is incident. Angle, i'is the exit angle,
N is the refractive index on the incident side, and N'is the refractive index on the exit side.

Therefore, in this case, as a result, the degree of freedom in the layout of the photometric optical path in the camera body is increased, a compact layout is possible, the camera body can be made compact, and the body shape can be reduced. The degree of freedom in design can also be increased.

Next, FIG. 3 shows an example of a reflection type Fresnel lens, and FIGS. 4 and 5 show other examples of the reflection type diffractive optical element.

Here, the pitch of the reflection type diffractive optical element 12 is d (d ', d "), the incident angle is i and the exit angle is i'.
Then, regarding the m-th order diffracted light of wavelength λ, the following equation (2)
Holds. sin (i) -sin (i ′) = m · λ / d (2)

Further, it is desirable that the pitch step h conforms to the following equation (3). h = m · λ / (n′−n) (3) In the formula (3), n is the refractive index of the medium on the incident side,
n'is the refractive index of the medium on the exit side, and in the case of the reflection type,
It is calculated as [n = 1, n ′ = − 1].

Here, FIG. 5 shows the so-called KINOF.
This is a reflection type diffractive optical element called ORM, and in this diffractive optical element, the step h of the pitch is expressed by the above formula (3).
In the case of, the m-th order diffracted light can be emphasized (theoretically, 100% of the incident light becomes the m-th order diffracted light).

That is, according to the present invention, by adopting the above basic structure, photometry is possible without requiring a window for photometry, and the degree of freedom in designing the camera body is high,
In addition, it is possible to easily obtain a photometric device for a lens shutter type camera with less parallax between the imaging surface and the photometric range.

[0028]

Embodiments Next, different embodiments of the photometric device for a lens shutter type camera according to the present invention will be described in detail with reference to FIGS.

First Embodiment FIG. 6 is a structural explanatory view showing the outline of a photometric device of a lens shutter type camera to which the first embodiment of the present invention is applied.

Also in the apparatus configuration shown in FIG. 6, the first embodiment is different from the photographic lens front portion 3 and the photographic lens rear portion 5 in the first embodiment.
And an aperture stop 4 arranged between the front part 3 of the taking lens and the rear part 5 of the taking lens to determine the size of the axial light flux 1 (see FIG. 1) on the optical axis, and imaging of film, CCD, etc. The surface 6 and the first reflecting member 9 which is located closer to the subject 2 (see FIG. 1) than the aperture stop 4 and does not hinder the passage of the axial light beam 1, and at least the first reflecting member. Second reflecting member 1 arranged on the optical path of the light beam 8 that is re-reflected by
1 and a light receiving means for photometry arranged on the optical path of the light beam 8 reflected by the second reflecting member 11, in this case, a photoelectric converting means 10.

In the structure of the first embodiment, the on-axis light beam 1 emitted from the subject 2 on the optical axis passes through the front portion of the front portion 3 of the photographing lens and is converted by the aperture stop 4 into the light beam. The size is determined, and the image is formed on the imaging surface 6 after passing through the rear portion 5 of the taking lens.

In this case, in order to allow the off-axis light beam 7 to pass through the opening of the photographing lens front part 3, the on-axis light beam 1
The light flux 8 that is formed to be larger than the range through which the object 2 on the optical axis passes and passes through a region other than the passing region of the photographing light flux 1 of the photographing lens front part 3 is a photographing lens front part 3 of the aperture stop 4.
After being reflected by the first reflecting member 9 and the second reflecting member 11 on the side, the light enters the photoelectric conversion means 10 for photometry.

Further, it is desirable that the arrangement position of the photoelectric conversion means 10 is an image forming position of the light flux 8, and the light flux 8 is bent a plurality of times by the first reflecting member 9 and the second reflecting member 11. When the required optical path length is ensured and the focusing operation is performed by the whole or a part of the front part 3 of the taking lens, it is always on the photoelectric conversion means 10 and the imaging surface 6 It is possible to form an image on the subject 2 at substantially the same distance.

Second Embodiment FIG. 7 is a structural explanatory view showing an outline of a photometric device of a lens shutter type camera to which a second embodiment of the present invention is applied.

In the second embodiment, the photographic lens front part 3 and the photographic lens rear part 5 (see FIGS. 1 and 6) and the photographic lens front part 3 and the photographic lens rear part 5 are arranged on the optical axis. The aperture stop 4 that determines the size of the on-axis light flux 1 (see FIGS. 1 and 6), the imaging surface 6 such as a film or a CCD, and the subject 2 (see FIGS. 1 and 6) rather than the aperture stop 4 ) Side, and a reflecting member having a refractive power arranged at a position that does not prevent passage of the axial light beam 1, and here, a reflecting member 12 having a refractive power such as a reflection type Fresnel lens or a diffractive optical element. , And at least the photoelectric conversion unit 10 for photometry arranged on the optical path of the light beam 8 re-reflected by the reflecting member 12.

Even in the configuration of the second embodiment, the behavior of the axial light beam 1 is the same as that of the first embodiment,
Further, a light beam 8 which is emitted from the subject 2 on the optical axis and passes through a region other than the passing region of the light beam 1 for photographing in the front portion 3 of the photographing lens is subjected to a lens action in the reflecting member 12 and is bent for optical measurement, and thereafter, for photometry. The light is incident on the photoelectric conversion means 10 and the same effect is obtained.

In the case of the second embodiment, another reflecting member or lens element is provided in the optical path between the reflecting member 12 and the photoelectric conversion means 10 so as to be advantageous in the layout of the camera. In particular, the aperture stop 4 and the rear part 5 of the taking lens are configured to move so that focusing can be performed, and the power of the reflecting member 12 is appropriately set and linked with the aperture stop 4. When the reflecting member 12 is made movable, it is always possible to form an image on the subject 2 which is on the photoelectric conversion means 10 and is at substantially the same distance as the imaging surface 6.

On the other hand, the reflecting member 12 may be formed by a continuous curved surface such as a concave mirror or a convex mirror, but in consideration of incidence from a wide angle, compactness, etc., as described above, the power is flat. It is desirable to use a reflective Fresnel lens or a diffractive optical element that can provide

Third Embodiment FIG. 8 is a structural explanatory view showing an outline of a photometric device of a lens shutter type camera to which a third embodiment of the present invention is applied.

In the apparatus configuration shown in FIG. 8, the third embodiment is constructed by arranging a plurality of photometric optical systems in the second embodiment. That is, the first photometric optical system is composed of the photographing lens front part 3, the reflecting member 12 having a refractive power, and the photoelectric conversion means 10. The second photometric optical system is similarly composed of the photographing lens front part 3. , A reflecting member 12 'having a refractive power, and a photoelectric conversion means 10'. In the first photometric optical system, the light beam 8 and the off-axis light beam 13 are formed.
Are introduced into the photoelectric conversion means 10, and in the second photometric optical system,
Among the respective luminous fluxes, a luminous flux 8'which is independent of the axial luminous flux 1 and the luminous flux 8 and an off-axial luminous flux 13 'are guided to the photoelectric conversion means 10'.

Here, FIG. 9 shows the state of each light beam guided to each of these photoelectric conversion means 10 and 10 '.

That is, in FIG. 9, the light beam 7 passes through the aperture stop 4 and is on the surface including the reflection member 12 and the optical axis. When viewed from the optical axis, the light beam 7 is opposite to the reflection member 12 side. An off-axis light beam which is emitted from an object point on the side and is incident, and a light beam 7 ′ passes through the aperture stop 4 and is on the surface including the reflecting member 12 and the optical axis, and is viewed from the optical axis. When the reflection member 1
The 2 side is an off-axis light flux that is emitted from an object point on the same side and is incident.

With respect to the first photometric optical system, a light beam which emits the same object point as the off-axis light beam 7 and reaches the reflecting member 12 exists near the off-axis light beam 7 like the off-axis light beam 13. On the other hand, on the other hand, the light flux that emits the same object point as the off-axis light flux 7 ′ and reaches the reflecting member 12 is not present because it is blocked by the support frame 14 or the like that holds the front portion 3 of the taking lens. In order to avoid this, there is a means for separating the support frame 14 and the like from the optical axis, but this is not desirable because of the problems such as the compactness of the taking lens and the occurrence of flare and ghost. Furthermore, the second
With respect to the photometric optical system, the light beam that emits the same object point as the off-axis light beam 7'and reaches the reflecting member 12 'exists near the off-axis light beam 7', like the off-axis light beam 13 '. That is,
By arranging a plurality of photometric optical systems in this way, it is possible to secure a relatively wide photometric range while avoiding the occurrence of flare and ghost while having compactness.

In FIG. 8, the reflecting members 12 and 1 are
The 2's are arranged symmetrically with respect to the optical axis, but they are not necessarily arranged symmetrically with each other. Further, by appropriately setting the reflection directions of the respective reflection members 12, 12 ', the photoelectric conversion means 10, 1
0'is integrally arranged, for example, each reflecting member 12
On the plane that is perpendicular to the line segment connecting
That is, in FIG. 9, it can be arranged on a plane perpendicular to the paper surface and including the optical axis.

Fourth Embodiment FIG. 10 is a structural explanatory view showing an outline of a photometric device of a lens shutter type camera to which a fourth embodiment of the present invention is applied.

Also in the apparatus configuration shown in FIG. 10, in the fourth embodiment, the taking lens front portion 3 and the taking lens rear portion 5 (see FIGS. 1 and 6), and the taking lens front portions 3 and 3 are provided.
It is arranged between the rear parts 5 of the photographing lens and is an on-axis light beam 1 on the optical axis.
Brightness diaphragm 4 for determining the size of (see FIGS. 1 and 6)
, A film type, a CCD, and the like, and a transmissive type disposed at a position that is closer to the subject 2 (see FIGS. 1 and 6) than the aperture stop 4 and does not hinder the passage of the axial light flux 1. A transparent member 15 comprising a Fresnel lens element or a diffractive optical element,
The reflecting member 16 is arranged on the optical path of the light beam 8 passing through the transmitting member 15, and the photoelectric conversion unit 10 for photometry is arranged on the optical path of the light beam 8 reflected by the reflecting member 16. .

Even in the structure of the fourth embodiment, the behavior of the axial light beam 1 is the same as that of the first embodiment,
Further, a light beam 8 which is emitted from the subject 2 on the optical axis and passes through a region other than the passage region of the photographing light beam 1 on the front part 3 of the photographing lens is deflected in its optical path while receiving a lens action in the transmissive member 15.
Further, the light enters the photoelectric conversion means 10 for photometry through the reflecting member 16, and the same effect can be obtained.

In the case of the fourth embodiment, the reflecting member 16 is provided with power, and it is advantageous in the layout of the camera in the optical path between the transmitting member 15 and the photoelectric conversion means 10. Further, a reflecting member or a lens element may be further arranged, or the reflecting member 16 may be eliminated and the light beam 8 may be directly guided to the photoelectric conversion means 10. Further, in order to secure the widest possible photometric range, a plurality of photometric optical systems may be arranged as in the third embodiment. Further, the transmissive member 15 may be arranged independently of other lens elements, but it is arranged on a part of the lens surface on the side of the aperture stop 4 on the front part 3 of the taking lens or on the lens surface in the vicinity thereof. But
It is advantageous in terms of cost, compactness, and assemblability. Examples of means for forming a part of the lens surface in this way include a molding method in which the lens surface itself is transferred to the mold shape of the molding die, or a lens surface. A replica method or the like in which a thin resin layer is molded on the top can be used.

Fifth Embodiment FIG. 11 is a schematic diagram showing the construction of a photometric device for a lens shutter type camera to which the fifth embodiment of the present invention is applied.

Also in the apparatus configuration shown in FIG. 11, in the fifth embodiment, the taking lens front portion 3 and the taking lens rear portion 5 (see FIGS. 1 and 6), and these taking lens front portions 3 and 3 are provided.
It is arranged between the rear parts 5 of the photographing lens and is an on-axis light beam 1
Brightness diaphragm 4 for determining the size of (see FIGS. 1 and 6)
An image pickup surface 6 such as a film or a CCD, transmission members 17 and 17 'formed of a transmission type Fresnel lens element or a diffractive optical element disposed in the front portion 3 of the photographing lens, and transmission members 17 and 17 thereof. Each of the photoelectric conversion means 10 and 10 'for photometry arranged on the optical path of the light beam 8 diffracted by'.

Even in the structure of the fifth embodiment, the axial light flux 1 emitted from the subject 2 on the optical axis is incident on the front portion 3 of the photographing lens, and the transmission members 17, 17 'are molded. A component (so-called zero-order light) that does not undergo the diffraction phenomenon in each of the transmissive members 17 and 17 'after passing through the surface where the transmissive members 17 and 17' are present, and the axial light flux 1
Goes through the aperture stop 4, the rear part 5 of the taking lens, and the imaging surface 6
The components imaged on and diffracted by the transmissive members 17 and 17 'are incident on the photoelectric conversion units 10 and 10' for photometry, respectively, and the same effect is obtained.

In the case of the fifth embodiment, it is desirable that each of the transmissive members 17 and 17 'be molded by using KINOFORM or the like so that diffracted light in the optical axis direction does not occur. Further, each of the transmissive members 17 and 17 'does not necessarily have to be formed on the entire surface of the lens. For example, as shown in FIG. 12, the required amount of light can be obtained by each photoelectric conversion means 10 and 10'. As an example, the transmissive members 17a and 17a 'may be molded on only a part of the lens surface. Further, optical elements such as lenses, reflecting members and prisms may be arranged in the optical path between the front part 3 of the photographing lens and the photoelectric conversion means 10 and 10 'so as to be advantageous in the layout of the camera. Good. Although not shown in FIG. 11, the photoelectric conversion means 10,
It is configured to be incident on any of 10 '.

[0053]

As described above in detail with reference to each embodiment, according to the present invention, the photographing objective lens provided separately from the finder objective lens and the image side of the incident surface of the photographing objective lens are provided. And a measuring light introducing unit provided on the object side of the aperture stop, and light that passes through the photographing objective lens and does not pass through the aperture stop through the measuring light introducing unit. It is possible to perform photometry without the need for a window for photometry at all. It has the excellent feature that it is easy to obtain a photometric device for a lens shutter type camera with little parallax between photometric ranges.

[Brief description of drawings]

FIG. 1 is a basic configuration explanatory diagram for photometry of a central portion of a photographing range in a photometric device for a lens shutter type camera according to the present invention.

FIG. 2 is a flowchart showing an example of an operation mode of the lens shutter type camera having the same basic configuration as above.

FIG. 3 is a partially enlarged cross-sectional view showing an example of a reflective Fresnel lens applied to the basic configuration of the above.

FIG. 4 is a partially enlarged cross-sectional view showing an example of a reflective diffractive optical element applied to the basic configuration of the above.

FIG. 5 is a partially enlarged cross-sectional view showing another example of the reflection type diffractive optical element applied to the above basic configuration.

FIG. 6 is a structural explanatory view showing an outline of a photometric device of a lens shutter type camera to which the first embodiment of the present invention is applied.

FIG. 7 is a structural explanatory view schematically showing a photometric device of a lens shutter type camera to which a second embodiment of the present invention is applied.

FIG. 8 is a structural explanatory view schematically showing a photometric device of a lens shutter type camera to which a third embodiment of the present invention is applied.

FIG. 9 is a structural explanatory view showing a state of each light beam guided to each photoelectric conversion means in the third embodiment.

FIG. 10 is a structural explanatory view showing an outline of a photometric device of a lens shutter type camera to which a fourth embodiment of the present invention is applied.

FIG. 11 is a structural explanatory view schematically showing a photometric device of a lens shutter type camera to which a fifth embodiment of the present invention is applied.

FIG. 12 is a front view showing another example of the respective transmissive members formed on a part of the lens surface of the front portion of the taking lens in the fifth embodiment.

FIG. 13 is a configuration explanatory view showing the outline of a conventional camera in which a photographic optical system and a photometric optical system are independent.

[Explanation of symbols]

1 On-axis light beam 2 Subject 3 Front part of shooting lens 4 Brightness diaphragm 5 Front part of shooting lens 6 Imaging surface 7, 7 ', 13, 13' Off-axis light beam 8, 8'Light beam 9, 11, 16 Reflecting member 10, 10 ′ Light receiving member (photoelectric conversion member) 12, 12 ′ Reflecting member (reflection type Fresnel lens element, diffractive optical element) 15, 15 ′, 17, 17 ′, 17a, 17a ′ Transmission member (transmission type Fresnel lens element, Diffractive optical element)

Claims (2)

[Claims] 1. A photographic objective lens provided separately from a finder objective lens, a brightness diaphragm provided on the image side of an entrance surface of the photographic objective lens, and an object side of the brightness diaphragm. A measuring light introducing unit that guides a part of the light beam that has passed through the photographing objective lens so as to deviate from the photographing optical path, and a light receiving unit that receives the luminous flux that has deviated from the photographing optical path by the measuring light introducing unit. A photometric device characterized by being provided. 2. The photometric device according to claim 1, wherein the measuring light introducing unit is a diffractive optical element arranged in a photographing optical system.