JPH0786632B2 - Wonder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a finder that is provided in a camera having a wide shooting range from infinity to a close range and that forms an aerial image without passing through a shooting lens.

[Conventional technology]

Conventionally, in the finder as described above, since the change in diopter due to the perspective of the subject is corrected by the eye adjustment function,
The finder didn't have a focusing function. Even if the finder has a large angular magnification γ,
This is because the close-up shooting distance is about 0.7 and the close-up shooting distance is too close due to the short-distance performance of the shooting lens, the focusing mechanism, the parallax of the finder, and the change in the diopter of the finder is small.

Recently, technological advances have made it possible for cameras with the above-mentioned finder to shoot at relatively short distances, but the angular magnification of the finder is | γ | <0.7.
Since there is no change, there is a finder with a parallax correction mechanism as in Japanese Utility Model Publication No. 56-5072, but there is no finder with a focusing mechanism yet.

Further, in the finder diopter correction method as disclosed in JP-A-49-88515, the correction is limited to the rangefinder portion of the finder with a rangefinder, and it is possible that the diopter greatly changes over the entire field of view. It is not taken into consideration, and it is difficult to use it in parallel with the parallel correction.

Recently, a camera equipped with a finder as described above is also provided with a zoom lens, and thus a zoom lens is also used for the finder.
However, when the zoom ratio of the zoom lens becomes large, it is necessary to increase the maximum angular magnification of the finder. That is, for example, if the angular magnification is set to the conventional finder on the long focus side, the angular magnification becomes too small on the short focus side, and it becomes difficult to see the details of the subject such as the facial expression of the person to be photographed. In particular, in the case where the long focal length side is a long focal length such that there is a telephoto effect, unless the angular magnification of the finder is sufficiently large, it is difficult to see the details of the subject.

In a finder without a focusing mechanism, the change in diopter due to the perspective of the subject becomes large in proportion to the square of the angular magnification. 9th
The figure shows a finder which is composed of _two thin lenses L ₁ and L _{2 and} has a diopter of zero for an object point at infinity. In this finder, the distance from the lens L ₁ to the subject 0 is s, the distance from the pupil P to the aerial image of the subject is s ′, and the distance from the lens L ₂ to the pupil P is e _P (both are positive on the right side of the figure). The unit is mm. The diopter D (day opter) of the subject 0 is as follows.

^{D = 1000γ 2 / {(1} -γ) / 1 -γ 2 e P + s) (1) provided that ₁ is the lens L ₁ of the power, in this example in the angular magnification of gamma is Fuainda gamma = - is _2/1 .

In a normal imaging area, | (1-γ) / ₁ | << | s |, | γ ² e _P | << | s |, so that the equation (1) is as follows.

D≈1000γ ² / s (2) Therefore, when | γ | exceeds 1, it becomes difficult to follow only with the focus adjustment ability of the eyes.

In addition, it is advantageous to perform close-up photography on the long focus side in that the photographing magnification can be large. Therefore, it is necessary to enable close-up photography on the long focus side. However, in a camera equipped with a finder as described above, it is necessary to correct the parallelism when taking a close-up image.

[Problems to be Solved by the Invention]

For the above reasons, with a camera equipped with a finder, in the case of a finder that performs close-up photography at high magnification, it is necessary to perform focus and parallel correction at the same time, but with the combination of conventional methods, both It must be done in two separate mechanisms, which is bulky and costly.

The present invention provides a finder that is provided in a camera with a variable shooting distance and that forms an image without passing through the photographic lens of the camera and that can perform focusing and parallel correction at the same time. is there.

[Means for Solving the Problems]

INDUSTRIAL APPLICABILITY The finder of the present invention is provided in a camera having a variable shooting distance to form an image without passing through the photographic lens of the camera, and is more preferable than an optical member for displaying an imaging range such as a field frame and a light frame in the finder. On the subject side and in the case of the zoom finder, the lens having the image-forming action, which is on the subject side of the member having the variable magnification action, is moved along the optical axis, and at the same time, moved in the direction perpendicular to the optical axis. Therefore, it is possible to keep the diopter of the finder within a certain range and to correct the parallax.

Further, the finder of the present invention, when considering the movement of the moving lens in a plane including the finder optical axis and the optical axis of the photographing lens, considers the movement amount of the lens on the optical axis as x, and the direction perpendicular to the optical axis. Is the moving amount, the focal length of the moving lens is f ₁ , the distance from the moving lens to the subject is s ₁ , the moving lens When the distance between the image forming position and the photographing lens is l, the following relationship is satisfied.

x≈−f ₁ ² / s ₁ (A) y≈lf ₁ / s ₁ (B) FIG. 1 is a conceptual diagram for explaining the content of the present invention, and the finder of the present invention is basically Is composed of a lens unit L ₁ and a lens unit L ₂ shown in these figures. Then, among them, the lens group L ₁ having the image-forming effect on the most object side is moved in the optical axis direction for focusing according to the distance of the object, and at the same time, is moved in the direction perpendicular to the optical axis for parametric correction. Therefore, the image taken by the lens group L ₁ of the subject imaged at the center of the screen by the taking lens TL is formed at a fixed position with respect to the lens group L ₂ located behind the finder lens group L _1. I was allowed to. That is, the shooting lens TL
Unrelated far object point 0 _∽ on the optical axis of the lens group Fuainda
When the image is formed at the position of I ₁ by L ₁ , the closest object point 0 _u on the optical axis of the taking lens TL is moved to the same position of I ₁ by moving the lens group L _{1 of the} finder to L ₁ ′. Can be focused on.

When the lens group L ₁ is moved as described above, the lens group L ₁
Differences x and y between the principal point position of L and the principal point position at L ₁ ′ in the optical axis direction and the direction perpendicular to the optical axis are expressed as follows. That is, the above expressions (A) and (B) may be satisfied.

x = −f ₁ ² / (s ₁ + f ₁ ) ≈−f ₁ ² / s ₁ y = lf ₁ / (s ₁ −f ₁ ) ≈lf ₁ / s _{1 In} this case, the lens group L ₁ moves continuously. Although it is most desirable to make it possible, even if it is moved stepwise, a sufficient effect can be obtained if the shape of the step is appropriately selected.

〔Example〕

 Next, an embodiment of the present invention will be described.

The data shown below show the specifications of the finder optical system according to one embodiment of the present invention.

f ₁ = −25.851 γ = −0.46 to −1.17 r ₁ ＝ −69.4200 d ₁ ＝ 1.5600 n ₁ = 1.49216 ν ₁ ＝ 57.50 r ₂ = 15.6930 d ₂ ＝ D ₁ r ₃ ＝ 22.7820 d ₃ ＝ 2.0000 n ₂ = 1.72916 ν ₂ = 54.68 r ₄ = −35.6780 d ₄ = 1.200 r ₅ = −11.9790 d ₅ = 1.3400 n ₃ = 1.80518 ν ₃ = 25.43 r ₆ = −50.2760 d ₆ = 1.0000 r ₇ = −434.0600 d ₇ = 2.9000 n ₄ = 1.49216 ν ₄ = 57.50 r ₈ = -9.7950 (aspherical surface) d ₈ = D ₂ r ₉ = -108.8020 d ₉ = 2.5000 n ₅ = 1.49216 ν ₅ = 57.50 r ₁₀ = -21.6280 (aspherical surface) d ₁₀ = D ₃ r ₁₁ ＝ 22.6270 d ₁₁ ＝ 43.4000 n ₆ = 1.49216 ν ₆ ＝ 57.50 r ₁₂ ＝ －22.6270 d ₁₂ ＝ 0.2000 r ₁₃ ＝ 9.9770 (aspherical surface) d ₁₃ ＝ 2.7600 n ₇ ＝ 1.49216 ν ₇ ＝ 57.50 r ₁₄ = 12.3320 d ₁₄ = 16.3000 r ₁₅ Eyepoint WST D ₁ 21.922 15.395 4.992 D ₂ 13.211 31.439 39.497 D ₃ 12.356 0.656 3.00 Aspherical coefficient E ₈ = 0.11634 × 10 ^-3 E ₁₀ = −0.17234 × 10 ^-4 , F ₁₀ ＝ 0.30064 x 10 ^-5 G ₁₀ = -0.64352 x 10 ^-7 , H ₁₀ = 0.90312 x 10 ^-9 E ₁₃ = -0.4 4249 × 10 ⁻⁴ , F ₁₃ = −0.36906 × 10 ⁻⁶ G ₁₃ = −0.65538 × 10 ^{−8 In} the data of the above examples, f ₁ is the focal length of the lens unit L ₁ , and γ is the angular magnification of the entire system. , R ₁ , r ₂ , ... are the radii of curvature of each lens surface, d ₁ , d ₂ , ... are the wall thickness and lens spacing of each lens, and n ₁ , n ₂ , ... Refractive index, ν ₁ , ν ₂ , ...
Is the Abbe number of each lens.

Each surface of FIGS. 8, 10 and 13 in the embodiment is an aspherical surface, and the shape of the aspherical surface is expressed by the following equation when y is the optical axis direction and S is the direction perpendicular to the optical axis. .

Where C is the curvature at the aspherical vertex E, F, G, H ... are aspherical coefficients.

The lenses (r ₁ , r ₂ , d ₁ , n ₁ ) of the above embodiment are the lens group L ₁ that moves for adjusting the diopter and the parallax.

In the camera incorporating this embodiment, for example, the optical axis distance l between the taking lens and the finder is 40 mm, the normal photographing area is from infinity (S = −∽) to S = −900 mm, and the closest photographing area is S = − It is set to 900mm to -500mm. Furthermore, in this embodiment, the lens unit L ₁ moves when switching between normal shooting and close-up shooting, and S = -3000 mm in normal shooting and S = -900 m switched to macro in accordance with camera specifications.
It is adjusted so that there is no parallax at m, and the diopter is set to be -0.5 diopter at S = -900 mm when the normal shooting state is switched to S = -∽ and the closest shooting state is switched. When the normal shooting state is switched to the close-up shooting state, the amount of movement of the lens unit L ₁ is 0.76 mm toward the object side parallel to the optical axis,
1.15 mm away from the taking lens perpendicular to the optical axis. The values of −f ₁ ² / s ₁ and lf ₁ / s ₁ at this time are 0.74 and 1.15, respectively.
And x, y almost agree with this value.

FIG. 3 is a diagram showing the diopter change of the finder of this embodiment. In this example, W and T are for wide and telescopic diopter correction, respectively, and W ′ and T ′ are for no diopter correction. Wide state with small angular magnification W, W ′
In, there is not much difference in the change due to diopter,
In the telephoto state where the angular magnification is large, T and T'are significantly different, and it is understood that the effect of the present invention is great. Since this effect increases as the angular magnification increases, as can be seen from the equation (2), it is effective and desirable to increase the switching points in the case of a finder with a larger angular magnification than this embodiment.

FIG. 4 is a diagram showing changes in the pararax of the finder of this embodiment. The values shown in this graph are positive in the direction away from the taking lens on a plane that passes through the rear focal position of the lens unit L _{1 in} the normal taking state and is perpendicular to the optical axis of the taking lens. The origin is an intersection of a point on the optical axis of the photographing lens at −3000, a straight line passing through the rear principal point of the lens unit L _{1 in} the normal photographing state, and the above plane. When expressed in this way, the amount of deviation between the actual center of the screen and the center of the finder is expressed by a tangent. Further, this graph is disregarded because the distortion aberration occurring near the optical axis of the lens unit L ₁ is small.

In this graph, the dotted line shows the case where the parallel correction was not performed in the very close range. From this figure, it can be seen that the parallel correction is effectively performed by moving the lens unit L ₁ at an appropriate point.

Note in order to increase the angular magnification than this example, is necessary to increase the absolute value of the magnification of the ocular side of the system than the one lens group L ₁ to the absolute value of the focal length of the lens group L ₁ in the large In either case, the apparent variation of the pararax becomes large, and it is desirable to increase the switching points.

Further, in this embodiment, when the lens unit L ₁ is moved in the close-up photographing state, the actual visual field becomes wider than when the lens unit L ₁ is not moved. This is because the focal length of the lens unit L ₁ is negative, and this is a phenomenon that is common to general taking lenses that have a focusing function by extending the front lens of a lens system in which the front lens is negative. Therefore, it is desirable to combine it with a taking lens of a front-lens feeding type in which the front lens is a negative lens, because it is possible to correct the change in the field of view due to the movement of the lens unit L ₁ .

The aberrations in this example are as shown in FIGS. In these aberration curve diagrams, the vertical axis of spherical aberration is the pupil diameter (radius) of the eye point, the vertical axis of astigmatism and distortion is the exit angle of the eyepiece system, and the horizontal axis of spherical aberration and astigmatism is It is a day opter. Of these aberration curve diagrams, FIG. 5 is an aberration curve diagram of the object point infinity in the wide state, and FIG. 6 is an aberration curve diagram when switching to the close-up shooting state for the object point S = −900 mm in the wide state, FIG. 7 is an aberration curve diagram of the object point at infinity in the tele state, and FIG. 8 is S = −90 in the tele state.
It is an aberration curve figure when it switches to a close-up photography state with respect to an object point of 0 mm. In FIGS. 5 and 7 of these figures, since there is no eccentricity, the aberrations are symmetrical in the upper and lower parts of the pupil and the upper and lower parts of the apparent visual field, but in FIG. 6 and FIG. The symmetry of aberration is eliminated to decenter L ₁ .

It should be noted that in FIG. 8, aberration is suddenly generated at the lower end of the apparent field of view, or this is an extremely extreme corner of one of the four corners in the finder field, and there is no practical problem.

In this embodiment, the aberration is relatively large in the close-up shooting state, but it is because the lens unit L ₁ is a negative lens. Therefore, when the parallax correction is performed in the close-up shooting state, the lens unit L ₁ is the optical axis of the shooting lens. This is because the lens moves in a direction away from, and therefore the peripheral portion of the lens unit L ₁ is used more. Therefore, if the lens unit L ₁ is composed of a positive lens, when the parallax correction is performed in the close-up shooting state, the lens unit L ₁ moves toward the optical axis of the shooting lens, and when the lens unit L ₁ is a negative lens. Compared with this, the vicinity of the center of the lens unit L ₁ is used, and the variation in aberration can be reduced. Moreover, the lens unit L ₁ is composed of a plurality of lenses,
If the lens unit L ₁ has a negative refracting power as a whole, the lens unit L ₁ is devised so that
Aberration variation can be made smaller than when L ₁ is a negative single lens.

Further, in this embodiment, the lens unit L ₁ is moved in parallel, but it is also possible to rotate the lens unit L ₁ in the plane including the optical axis of the photographing lens and the optical axis of the finder simultaneously with the parallel movement. Accordingly, the moving mechanism of the lens unit L ₁ can be simplified, and the off-axis aberration can be adjusted.

Moreover and when the distance between principal points constitute a lens group L ₁ by a plurality of lenses or thick lens becomes large, a position rear principal point of the lens group L ₁ is a distance from the position of the lens group L ₁ If it exists, the rear principal point can be moved to correct the parallelism simply by rotating the lens unit L ₁ in a plane including the optical axis of the taking lens and the optical axis of the finder.

〔The invention's effect〕

The finder of the present invention can correct the diopter change due to the perspective of the subject and the parallelism by moving a part of the lens of the finder, and since the lens movement is simple, it can be configured with simple parts and can be made at low cost. It is a thing.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing the contents of the present invention, FIG. 2 is a diagram showing a lens configuration of an embodiment of the present invention, FIG. 3 is a diagram showing a diopter change of the embodiment, and FIG. FIGS. 5 to 8 are graphs showing various changes in the parallax, FIGS. 5 to 8 are aberration diagrams of the above-described embodiment, and FIG. 9 is a graph showing the image formation state of a conventional finder.

Claims (2)

[Claims] 1. A finder provided in a camera having a variable shooting distance to form an image without passing through a shooting lens, the zoom finder being closer to a subject than an optical member for displaying a shooting range among lenses constituting the finder. In the case of, in the case of a lens closer to the subject than the lens having a zoom function, the diopter is moved along the optical axis to keep the diopter within a certain range, and at the same time, the lens is moved in the direction perpendicular to the optical axis. A finder that is characterized by performing parallax correction by moving it. 2. The amount of movement of the movable lens on the optical axis in a plane including the optical axis of the finder and the optical axis of the photographing lens is x, and the amount of movement in a direction perpendicular to the optical axis is y. When the focal point of the moving lens is f ₁ , the distance from the moving lens to the subject is s ₁ , and the distance between the moving lens imaging position and the shooting lens is 1 Finder that satisfies the relationship of.