JPH0786635B2 - Imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a photographing device having a variable photographing field angle.

[Prior Art] Conventionally, as a shooting device with a variable shooting angle of view, there is a method of changing the angle of view (= changing the shooting magnification) by changing the focal length on the lens side like a camera equipped with a zoom lens. It is common. However, as disclosed in JP-A-61-223831, the angle of view is not changed on the lens side, the trimming code is imprinted in the margin of the film, and this code is automatically read during stretching. It has been proposed that desired trimming is performed, and then the image is stretched and printed on photographic paper, resulting in the effect of changing the angle of view. In other words, although the entire predetermined exposure range of the film is exposed by photographing, the photographer specifies a narrower range than that range, and the photographed image shows the specified range.

[Problems to be Solved by the Invention] However, in order to display the angle of view at the time of trimming in the finder, the field frame of the finder must be made small. For this reason, the screen shot is extremely small, making it a difficult finder.
On the other hand, in U.S. Pat. No. 4,652,104, a finder is provided separately from a photographing lens, and a finder objective lens is used as a zoom lens to realize a field of view during trimming without changing the size of a field frame. However, in this method, the zoom ratio of the objective lens has to be large, and therefore there are many design difficulties.

An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional example and realize a pseudo telephoto camera having a large zoom ratio.

[Means for Solving the Problems] The structure of the present invention for achieving the above-mentioned object is, in order from the object side, an objective lens group and a variable finder field arranged near the image plane of the objective lens group. It has a frame and an eyepiece group with a variable focal length, and changes the focal length of the eyepiece group according to the size of the finder field frame. As a result, even if the size of the finder field frame is changed, the finder field image with the same viewing angle can always be formed by changing the focal length of the eyepiece.

[Example] Hereinafter, a specific description will be given with reference to the drawings.

FIG. 1 is an example in which the present invention is applied to a single-lens reflex camera.
Reference numeral 1 denotes a photographing lens (also serves as an objective lens of a finder in this embodiment), 2 is a rotating mirror for retracting information during photographing, 3 is a focusing plate, 4 is a finder field frame whose size can be changed, 5 Is the penta roof prism,
Reference numeral 6 denotes an eyepiece lens having a variable focal length, in which the two lenses move independently. 7 is a film. Reference numeral 8 is a pseudo-telephoto indicator, and when the operator operates the indicator 8, the trimming code is imprinted on a part of the film 7 by the code imprinter 9.

Now, the imaging plane of the taking lens 1 is near the field frame 4, and by reducing the size of the field frame, a desired trimming state can be displayed in the finder. However, that alone makes the viewfinder frame too small to see. Therefore, by shortening the focal length of the eyepiece lens group 6 and increasing the magnification of the eyepiece lens,
Make it look the same as when trimming. Furthermore, if the size of the field frame 4 and the focal length of the eyepiece lens group 6 are moved in a certain relation, the photographer can always observe the field frame in the same size as when the field frame was not trimmed.

FIG. 2 shows an embodiment of a method for changing the size of the field frame 4 according to the focal length of the eyepiece lens 6. FIG. 2 (a) is a cross-sectional view showing the structure of the finder field frame 4, and 4a is a polarizing plate attached to the upper glass plate 4b, which cooperates with the liquid crystal substance 4e described later to transmit or block light rays. It is something that 4-1, 4-2, 4-3
Are transparent electrodes that make up the large, medium, and small field frames, respectively.
It is formed on the lower surface of the upper glass plate 4b by a vacuum vapor deposition method. 4c is a spacer forming a space for enclosing the liquid crystal substance 4e between the upper glass plate 4b and the lower glass plate 4d,
It is adhered to the upper glass plate 4b and the lower glass plate 4d.
Numeral 4-4 is a transparent electrode formed on the upper surface of the lower glass plate 4d by a vacuum deposition method.
-3, and it is possible to change the transmittances of the visual field frames 4-1, 4-2, and 4-3 by applying a voltage between them. FIG. 2B is a plan view of the finder field frame 4 seen from above, and shows the relationship among the large, medium, and small field frames 4-1, 4-2, and 4-3. The transparent electrodes forming the visual field frames 4-1, 4-2, and 4-3 are fixed contacts 11, 11 of, for example, a rotary switching switch SW provided on the outer periphery of a cam cylinder (not shown) that moves the eyepiece 6. It is connected to 12 and 13, respectively. On the other hand, the sliding contact 14 of the rotary switching switch SW is connected to one pole of the driving power source E. The other station of the driving power source E and the transparent electrode 4-4 below the finder field frame 4 are both grounded.
If no trimming is performed here, the eyepiece 6
Has the longest focal length, that is, the smallest magnification, and the sliding contact 14 of the rotary switch SW provided on the outer periphery of the cam barrel that moves the eyepiece is connected to the fixed contact 11 to generate the voltage. Is applied, the field frame 4-1 becomes opaque and the imaging field of view is displayed. For medium trimming, turning the cam barrel of the eyepiece slightly shortens the focal length of the eyepiece, that is, the magnification becomes medium, and at the same time, the sliding contact of the rotary switching switch SW 14
Is connected to the fixed contact 12 and a voltage is applied to the upper transparent electrode of the visual field frame 4-2 to make the visual field frame 4-2 opaque to display the photographing visual field in the case of medium trimming. Next, when performing the most trimming, turning the cam barrel of the eyepiece lens causes the focal length of the eyepiece lens to become the shortest, that is, the highest magnification, and at the same time the sliding contact 14 of the rotary switching switch SW is the fixed contact. By being connected to 13, a voltage is applied to the transparent electrode which constitutes the visual field frame 4-3, and the transparent electrode becomes opaque to display the photographing visual field at that time.

That is, in general, when each side of the field frame is trimmed to 1 / n, the size of the field frame can always be observed to be constant by setting the focal length of the eyepiece lens to 1 / n.

FIG. 3 shows a second embodiment of the present invention, which is an example applied to a camera in which a taking lens 10 and a finder are separately provided. In the finder of FIG. 3, 1 is an objective lens group capable of zooming, 11 is a field lens, 4 is a finder field frame, 12 is an inverting prism group, 6 is an eyepiece lens with a variable focal length, 10 is a photographing lens group, and 7 is It is a film. The finder system can change the viewing angle by changing the focal length of the objective lens group 1. At the same time, the viewing angle can be changed by reducing the size of the viewing mask. In this case, since the field frame looks small to the observer, it is possible to change the focal length of the eyepiece lens 6 to a shorter direction as in the first embodiment so that the finder field frame always looks the same size. is there. Particularly, in the second embodiment, the zoom effect of the objective lens and the zoom effect of the trimming of the field frame are synergistically compatible with high magnification zoom.

Incidentally, in the first embodiment, the taking lens 1 may be a zoom lens. In this case, the zooming effect of the photographing lens and the zooming effect of the trimming are synergized, and an extremely high zooming effect can be expected.

In the second embodiment, the objective lens group 1 may be a single focus lens. This is because the zoom effect can be produced only by trimming.

As described above, by changing the focal length of the eyepiece lens according to the size of the finder field frame,
(A) An easy-to-view finder system in which the field of view frame is always the same size. (B) A high-power zoom finder system compatible with high-power zoom photographic lenses has become possible.

[Brief description of drawings]

FIG. 1 is an optical sectional view showing an embodiment of the present invention. FIG. 2A is a sectional view of the finder field frame, and FIG. 2B is a plan view. FIG. 3 is an optical sectional view showing another embodiment. In the figure, 4 is a finder field frame, and 6 is an eyepiece.

Claims (2)

[Claims] 1. In a photographing apparatus capable of designating a trimming range narrower than a normal range, a finder has a variable finder field frame of variable size and a observable field frame and a variable focal length. Has an eyepiece,
An image pickup apparatus characterized by changing a focal length of an eyepiece lens according to a size change of a finder field frame when a trimming is designated. 2. The photographing apparatus according to claim 1, wherein the eyepiece has a magnification increased as the finder field frame decreases.