JP2880132B2 - Stereo camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereo camera, and more particularly, to a stereo camera provided with a mechanism for adjusting a distance between optical axes of two photographing lenses.

[0002]

2. Description of the Related Art In a stereo camera for taking two pictures simultaneously by a pair of left and right photographing lenses, the distance between the optical axes of the two photographing lenses is generally fixed. is there. This type of stereo camera with a fixed inter-optical axis distance increases the positional deviation of the subject image on the left and right photographing screens due to the parallax of the two photographing lenses as the subject distance decreases, and as shown exaggeratedly in FIG. Stereo shooting areas (b to
The non-overlapping regions (ab, cd) increase outside each of c).

When this photographic film is mounted on a stereo slide mount and viewed with a stereo slide viewer, a non-overlapping area (ab, cd) does not form a three-dimensional image, and as shown in FIG. The edge of the window of the slide mount overlaps and becomes obstructive. Therefore, by preparing a plurality of types of stereo slide mounts having different window widths and selecting a stereo slide mount having an appropriate window width, means for masking non-overlapping areas (ab, cd) of the left and right screens. Is adopted. Therefore, it is known that there is a drawback that the loss of the screen width is large and it is not easy to determine the mask amount and the horizontal position of the screen when mounting.

Therefore, the applicant of the present application has provided an automatic inter-optical axis distance adjustment mechanism for always matching the fields of view of the left and right photographing lenses at the focal distance so that the parallax is automatically corrected according to the photographing distance. Stereo camera (Japanese Patent Application No. Hei 8-05)
No. 3476). This stereo camera is
Since the distance between the optical axes is automatically adjusted so that the fields of view of the left and right photographing lenses always coincide with each other at the focusing distance, the loss of the stereo photographing area can be reduced, and the quick shooting performance is excellent. There is almost no situation where all the subjects in the screen are at the focal distance, and the subjects are often mixed at various distances. In addition, since human vision has a collimation effect that focuses on a short-distance subject, when focusing on a long-distance main subject, the distance between the optical axes of the lenses is reduced for a closer subject within the same screen. The distance correction amount may be insufficient. When the stereo slide shot in this way is attached to the viewer and viewed, a short-distance subject forms an extremely close-up image and looks unnatural, and in order to correct this, the left and right screens are mounted at the time of mounting. It may be necessary to mask the outer region appropriately.

Therefore, even in a stereo camera provided with an automatic inter-optical axis distance adjustment mechanism, the window width of the slide mount is reduced at the time of mounting except for short-distance photographing with a distance of about 1 to 2 meters or less, or other than close-up photographing. It is often necessary to perform parallax correction by means such as a mask or a mask frame.

Therefore, there arises a technical problem to be solved in order to provide a stereo camera having an automatic inter-optical axis distance adjusting mechanism capable of minimizing the loss of a stereo shooting area in an actual shooting situation. Accordingly, an object of the present invention is to solve the above problems.

[0007]

SUMMARY OF THE INVENTION The present invention proposes to achieve the above-mentioned object, and mounts two photographing lenses on independent lens boards, respectively. In a stereo camera provided with an automatic optical axis distance correction mechanism that moves in parallel in the approaching direction, the optical axes of the two photographing lenses approach, and matches the fields of view of the two photographing lenses at the focal distance,
From the extended position where the principal points of the two photographing lenses are shifted in the approaching direction than the left and right screen pitches at the infinity focal position, from the extended position where the fields of view of the two photographing lenses coincide at the shortest focusing distance. Another object of the present invention is to provide a stereo camera characterized in that a slide guide for a lens board that moves on a straight line is provided, and the distance between optical axes is automatically corrected by the slide guide.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a trinocular stereo camera 1 as an example of a stereo camera. A finder lens 2 is arranged at the center of the front surface of a camera body, and a pair of photographing lenses 3L and 3R are arranged in a horizontal line on the left and right sides. The axes are parallel and coplanar. Shooting lens 3
A focal plane shutter (not shown) is disposed immediately before the film surface behind the L and 3R, and a 45 ° reflex is provided behind the finder lens 2 having the same lens characteristics as the photographing lenses 3L and 3R. A mirror (not shown) is fixed. The light incident on the finder lens 2 forms an image on an upper focusing screen 4 via a reflex mirror, and an erect image can be observed through a pentaprism 5 and an eyepiece 6 as in a general single-lens reflex camera. it can.

FIG. 2 shows a focus adjustment mechanism of the stereo camera 1 with an automatic adjustment of the distance between the optical axes. The left and right lens boards 8L and 8R on which the photographing lenses 3L and 3R are mounted are extended to a lens mount 7 of the camera body. The slide guides 9L and 9R that skew in the direction in which the distance between the optical axes of the photographing lenses approach each other are formed bilaterally symmetrically.
Slider portions 10 provided on both left and right side surfaces of L, 8R are fitted to slide guides 9L, 9R. The lens board 8C of the finder lens 2 is mounted on a slide guide 9C formed in the optical axis direction, and can move straight in the optical axis direction.

An involute tooth profile camshaft 11 for focusing is provided in the camera body in the left-right direction, and arms 12L, 12C, 12R are provided on the lens boards 8L, 8C, 8R to project rearward from the lower ends thereof. As shown in FIG. 3, the camshaft 11 is inserted into rectangular cross-sectional grooves 13L, 13C, 13R formed on the upper surface of the arm.
Of the involute cam 11a is engaged.

Therefore, when the focusing knob 14 fitted on the end of the camshaft 11 is rotated, the photographing lenses 3L, 3R and the finder lens 2 are integrally advanced or retracted according to the rotation direction of the camshaft 11. Focus adjustment can be performed by looking through the eyepiece 6. When the photographing lenses 3L, 3R and the finder lens 2 are extended, the photographing lenses 3L, 3R are moved to slide guides 9L, 9R.
The image is shifted in the approaching direction along R, and the parallax of the photographing lenses 3L and 3R with respect to the subject is automatically corrected. Also,
Involute cam 11a and rectangular sectional grooves 13L, 13
Combination with C and 13R enables high-precision focus adjustment without backlash.

FIG. 4 shows the relationship between the focus of the photographing lens and the distance between the optical axes for matching the fields of view of the left and right photographing lenses 3L and 3R at the focusing distance.
Assuming a thin lens, the focal length of the lens ‥‥‥‥‥‥‥‥‥‥‥‥‥ f The distance from the subject to the principal point of the lens ‥‥‥‥‥ L From the focal position of the lens to the imaging position If 距離 Δif, then Δif = f ² / ( L−f ) , so that the distance between the principal point of the lens and the film surface is f + Δif.

Further, each of the shift amount Sl of the left and right lens for matching the field of view of right and left photographing lens in focus distance, the pitch of the left and right exposed surface of the stereo camera When P ₁ Sl = (P ₁ / 2) × (f + Δif ) / ( L + f + Δif), and as the distance L from the subject to the principal point of the lens decreases, the left and right photographing lenses are moved in the directions approaching each other by the shift amount S1, so that the in-focus distance is always maintained. , The fields of view of the left and right photographing lenses coincide.

[0014] Figure 5 is a focal length of the lens is 36 mm, is left exposed surface pitch P ₁ in the case of 66 mm, a table showing the relationship between the feed amount Δif and the shift amount Sl of the lens based on the above equation, the photographic lens The locus of the principal point draws a gentle exponential curve as shown by a broken line in FIG.

The focus adjustment mechanism of the stereo camera according to the present invention, which has an automatic adjustment between the optical axes, is indicated by a solid line in FIG.
The photographing lenses 3L and 3R are formed so as to skew linearly along the tangent line of the shortest photographing distance point of the calculated principal point locus indicated by the broken line (here, the shortest photographing distance is 600 mm, the maximum lens extension amount). Δif = 2.30 mm). Therefore, the fields of view of the left and right photographing lenses 3L and 3R coincide with each other at the shortest photographing distance, but the shift amount S1 does not become zero in the infinity photographing state where the extension amount Δif is zero. It is designed so that the distance correction amount is slightly excessive.

However, as described above, in close-up photography, a subject at a shorter distance than the main subject is rarely put on the screen, and the fields of view of the left and right photographing lenses at the in-focus position should be matched. When photographing with focus on a distance, there is often a case where another subject exists closer than the focus position. Therefore, as the present invention is configured such that the field of view of the left and right photographing lenses coincides with each other at a shorter distance than the in-focus position as the photographing distance becomes longer as in the case of the present invention, this has often been caused by the influence of a close-range subject. Insufficient correction of the distance between the optical axes can be eliminated, and the correction amount is set more practically.

FIG. 7 and FIG. 8 show another embodiment of the focus adjusting mechanism with automatic adjustment of the distance between the optical axes. The right and left sides of the camshaft 21 shown in FIG. 7 correspond to the oblique directions of the photographing lenses 3L and 3R, respectively. Helical involute cam 22 at an angle
L, 22R, and an involute cam 22 parallel to the camshaft 21 in the center as in the stereo camera of FIG.
C is provided.

Lens board 23 for taking lenses 3L and 3R
The arms 24L and 24R of the L and 23R are provided with rectangular cross-sectional grooves 25L and 25R in a direction orthogonal to the sliding direction of the lens boards 23L and 23R, and the helical involute cams 22L and 22R mesh with each other, and
Rectangular cross-sectional groove 25 of arm 24C of lens board 23C
C meshes with the center involute cam 22C.

In this focus adjusting mechanism with automatic adjustment between the optical axes, the direction of the force acting on the lens boards 23L and 23R by the rotation of the helical involute cams 22L and 22R matches the sliding direction of the lens boards. There is an advantage that the boards 23L and 23R slide more smoothly.

In the stereo camera of the present invention, the parallax of the photographing lenses 3L and 3R is automatically corrected in conjunction with the focus adjustment, and in a long-distance photographing, a subject at a short distance from the in-focus position is displayed on the left and right screens. Images will be taken at almost the same position. In addition, since the distance between the optical axes is automatically corrected, there may be a case where the correction amount between the optical axes is slightly insufficient for a subject extremely close to the focusing distance. Compared with a conventional stereo camera having no mechanism, as well as a conventional stereo camera with an automatic optical axis distance adjusting mechanism, the degree of insufficient correction is significantly reduced.

Therefore, when mounting a film on a stereo slide mount, there is almost no need to adjust the film pitch to correct parallax, and use a stereo slide mount provided with a window almost the same size as the actual screen size. When the is mounted at a fixed position, a stereoscopic image of a foreground subject is not formed at a close distance when viewed with a stereo slide viewer, and a stereo slide with a natural stereo effect is obtained.

As another embodiment, a rangefinder type rangefinder 32 may be mounted in place of a pentaprism finder like a twin-lens stereo camera 31 shown in FIG. 9, and a transmission type real image type finder. May be. Further, for example, a known active or passive autofocus control mechanism is provided by providing a stepping motor for driving a distance measuring element, an MPU, and a camshaft for focus adjustment, and the autofocus control mechanism for automatically adjusting the distance between optical axes is provided. It may be automatically controlled by a focus control mechanism.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the technical scope of the present invention, and the present invention naturally extends to those modifications. It is.

[0024]

As described above, according to the stereo camera of the present invention, the field of view of the left and right photographing lenses at the focal distance coincides in close-up photographing, and the parallax is completely corrected. The fields of view of the left and right photographing lenses coincide with each other at a shorter distance than the focusing distance. Therefore, the unnaturalness of the perspective caused by the influence of human collimation on the close-up subject at the long distance shooting is eliminated, and almost ideal stereo effect can be obtained at any shooting distance.

[Brief description of the drawings]

FIG. 1 is a front view of a three-lens stereo camera, showing an embodiment of the present invention.

FIG. 2 is a plan sectional view of the trinocular stereo camera of FIG. 1;

FIG. 3 is a sectional view showing a fitted state of the involute camshaft and the groove in FIG. 2;

FIG. 4 is an explanatory diagram showing a relationship between a focal point of a photographing lens and a distance between optical axes for matching left and right lens fields of view.

FIG. 5 is a table showing a numerical example of a shift amount S1 with respect to an extension amount Δif of a photographing lens.

FIG. 6 is a graph illustrating a locus of a principal point of a photographing lens.

FIG. 7 is a plan sectional view of a trinocular stereo camera according to another embodiment.

FIG. 8 is a perspective view of a lens board and a cam shaft of the stereo camera of FIG. 7;

FIG. 9 is a front view of a binocular stereo camera according to another embodiment.

FIGS. 10 (L) and (R) are explanatory diagrams of photographing results of a conventional stereo camera.

FIG. 11 is an explanatory diagram showing screen loss in a conventional stereo camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Trinocular stereo camera 2 Finder lens 3 Shooting lens 4 Focusing plate 5 Pentaprism 6 Eyepiece 7 Lens mount part 8 Lens board 9 Slide guide 10 Slider part 11 Cam shaft 11a Involute cam 12 Arm 13 Rectangular groove 14 Focusing knob

Claims (1)

(57) [Claims] 1. Two photographing lenses are mounted on independent lens boards, respectively, and as the lens board is extended, the lens boards move in parallel in the approaching direction so that the optical axes of the two photographing lenses come close to each other and focus. In a stereo camera provided with an automatic optical axis distance correction mechanism for matching the fields of view of two photographing lenses at a distance, the principal point of the two photographing lenses is closer to the infinity focus position than the left and right screen pitches. A slide guide of a lens board that moves on a straight line connecting the reduced positions where the fields of view of the two photographing lenses coincide at the shortest focusing distance from the extended position shifted to is provided, and the distance between the optical axes is automatically set by the slide guide. A stereo camera characterized by correcting.