JPH03294833A - Finder optical system - Google Patents

Abstract

PURPOSE:To obtain the finder optical system which is compact and low in cost by moving a photographic lens and the lens of the finder optical system simultaneously. CONSTITUTION:The lens barrel of the photographic lens consists of a fixed barrel 30 and a cam barrel 20, which is provided with not only a cam groove 21 for 1st lens group movement and a cam groove 23 for 2nd lens group movement, but also a cam projection 22 for finder lens movement. This optical system is equipped with a means which enlarges an image corresponding to a range, predetermined according to respective zooming positions of the photographic lens among images formed on a photographic medium through the photographic lens capable of zooming, fully to a visual field frame at the respective zooming positions of the photographic lens. This means is driven by a driving system simultaneously with the power varying drive of the photographic lens. In this case, the photographic lens and the lens of the finder optical system I are moved simultaneously. Consequently, the optical system can be made compact and low in cost.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a finder optical system used in a camera, and more specifically to a finder optical system useful in a camera constituting a trimming system. Regarding.

The Shikatachi Kaibrie Trimming System uses the film shown in Figure 4 (a) (
By imprinting information specifying a predetermined range in the image forming area B of 50), that is, a part of the area A including the center, onto a predetermined portion (51) of the emulsion surface of the film (50), the print This is a system in which area A is enlarged so that printing can be performed on area A' of photographic paper (52) shown in the figure (opening). Specifically, when shooting in trimming mode, trimming information in the form of a code signal is recorded on a predetermined portion (51) of the film by a code imprinting unit, and when printing, this information is read by a reading device. , the printing device performs enlargement zooming according to that information. As shown in Figure 4 (c), the trimming information is obtained by transmitting the light from the light emitting diodes LEDI to LED3, which are turned on based on the code signal, to the film via optical fibers (53), (54), and (55) when the shirt is released. (50) and is imprinted onto the film (50) by exposing the predetermined portion (51) to light. This will be referred to as "electronic zoom."

By the way, it is more convenient for the finder of a camera compatible with such a system to be able to view the trimming area (the area A) in a larger size than in a smaller size during the trimming shooting mode. Therefore, it is desirable to make the image of the cropping area visible over the entire field frame of the finder.

On the other hand, if the photographic lens has a variable magnification function, the finder optical system must also perform optical magnification corresponding to the variable magnification of the photographic lens.

This variable magnification of the photographic lens is called "real zoom."

As a finder optical system that performs zooming compatible with real zoom and electronic zoom, for example, Japanese Patent Laid-Open No. 61-2
What is proposed in Publication No. 85432 and JP-A-1-1
There are some proposals in Japanese Patent No. 29224 and Japanese Patent No. 1-129225.

In the camera proposed in Japanese Unexamined Patent Publication No. 61-285432, which allows for this, electronic zoom is performed after the photographing lens is in the telephoto state. The lenses that make up the finder optical system are
It is connected to the photographic lens through a common gear, and during real zoom, it moves together with the photographic lens to change the magnification. Non-slanted parallel cam grooves are provided in the cam barrel of the photographic lens so that only the finder optical system changes magnification while the photographic lens remains in the telephoto state during electronic zooming. However, this finder optical system has the problem that if the cam groove is made longer, the strength of the lens barrel becomes weaker, and if the strength is maintained at an appropriate level, the size of the finder optical system increases.

Also, JP-A-1-129224 and JP-A-1-129
In the finder optical system proposed in Publication No. 225,
Zooming equivalent to real zooming is performed using an objective lens, and zooming equivalent to electronic zooming is performed using an eyepiece lens. Since zooming, which corresponds to real zooming, is performed at the same time as changing the magnification of the photographic lens, the driving force of the photographic lens can be used to drive the objective lens. but,
During electronic zooming, the photographing lens does not change the magnification, so to drive the eyepiece lens, it is necessary to provide a separate actuator dedicated to the finder or to use it by switching with another actuator. As a result, there are problems in that the configuration of the finder optical system becomes complicated and the cost increases.

It is an object of the present invention to solve such problems and provide a finder optical system that has a simple configuration that does not require an actuator dedicated to the finder, and that can be made compact and low in cost.

In order to achieve the above-mentioned object, the finder optical system of the present invention has a viewfinder optical system that corresponds to a predetermined range according to each zooming position of the photographic lens among the images formed on the photographic medium through the zoomable photographic lens. The camera is characterized in that it includes means for enlarging the image to the full field frame at each zooming position of the photographic lens, and that the means is driven by a drive system simultaneously with the zooming drive of the photographic lens.

Furthermore, the finder optical system of the present invention includes an objective lens, an inversion optical system that inverts the image formed by the objective lens vertically and horizontally, and an eyepiece that guides the image to the pupil, and the objective lens It may be configured to be driven by means.

As described above, the finder optical system is used to photograph images that correspond to predetermined ranges according to each zooming position of the photographic lens among the images formed on the photographic medium through the zoomable photographic lens. If the lens is provided with a means for enlarging the field of view to the full extent at each zooming position, and the means is configured to be driven by a drive system at the same time as the zooming of the photographic lens is driven, the movement of the photographic lens and The lens of the finder optical system is moved simultaneously, and an image corresponding to a predetermined range of the image formed on the photographic medium through the photographic lens is enlarged to fill the field frame at each zooming position of the photographic lens.

Further, the object lens comprises an objective lens, an inversion optical system that inverts the image formed by the objective lens vertically and horizontally, and an eyepiece that guides the image to the pupil, and the objective lens is configured to be driven by the means. Then, the finder optical system is easily linked with the photographic lens.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a state in which an embodiment of the present invention is applied to a photographic lens, in which a finder section (I) and a photographic lens section (n
) can be broadly divided into Finder section (I)
and the photographing lens section (n) are drawn as being on the same plane to make it easier to understand their interlocking relationship, but in reality the finder section (I) is drawn in a horizontal cross-sectional view, whereas The photographing lens section (n) is shown in a vertical cross-sectional view.

The photographing lens consists of, in order from the subject side, a lens group (41) having a concave-convex structure and having positive power, an aperture (43), and a second lens group (42) having a concave-convex structure and having negative power. . FIG. 1 shows the photographic lens in a wide-angle state. When transitioning to the telephoto state, the 1st lens group (41) and the 2nd lens group (42) each move toward the subject with an arrow (M).
It is extended as shown in (1) and (M2), but at this time, the amount of movement of the second lens group (42) is greater.

The lens barrel of the photographic lens consists of a fixed barrel (30) and a cam barrel (20).
). As shown in Figure 2,
The cam cylinder (20) has a cam groove (21) for moving the 1171st group.
In addition to the cam groove (23) for moving the second lens group, a cam protrusion (22) for moving the finder lens is also provided. The gear (19) provided on the cam barrel (20) is the first
Since it meshes with a gear (9) provided on the lens barrel rotation motor (10) shown in the figure, the cam barrel (20) rotates as the motor (10) rotates. The cam groove for moving the 1171st lens group (21) and the cam groove for moving the second lens group (23) include the second lens group fixing part (31) that fixes the second lens group (41), and the second lens group ( 42) are engaged with the second lens group fixing portions (32). Therefore, each lens group moves as the cam cylinder (20) rotates.

The finder optical system consists of a concave lens (G1) in order from the subject side.
) and an objective lens (1) consisting of a convex lens (G2).

It consists of a roof mirror (3), a condenser lens (4), a prism (5), and an eyepiece (6). This embodiment is a real image finder, and the convex lens (G2
) is moved to change the magnification and guide the light beam from the subject to the oblique surface (7). The convex lens (G2) is the G2 fixed part (2)
The G2 fixing portion (2) is pressed against the finder lens moving cam protrusion (22) by a spring or the like. Therefore, the magnification of the finder is changed as described above by rotating the cam cylinder (20) and moving the convex lens (G2) by being pushed by the cam projection (22). In FIG. 1, the movement of the convex lens (G2) at the time of transition from the wide-angle side to the telephoto side is indicated by an arrow (m).

When the cam cylinder (20) rotates in this manner, information on the trimming rate according to the focal length of the photographing lens according to the movement of each lens is given to the film (44).

In this embodiment, the movement of the convex lens (G2) is controlled by the cam cylinder (20).
The convex lens (G2) may be moved directly from the motor (10) through a speed reduction system without using the cam cylinder. Further, the magnification of the finder optical system can be changed by moving not only the objective lens (1) but also the eyepiece lens (6) and the like.

Next, the relationship between the finder magnification and the corresponding composite focal length will be explained. Here, the composite focal length refers to the composite focal length of the real zoom focal length and the electronic zoom focal length.

FIG. 3 shows the relationship between the electronic zoom (EZ) variable magnification ratio (vertical axis) and the composite focal length f(x) (horizontal axis).

Zooming in this embodiment is indicated by a - dotted chain line (at→0). This means that the magnification is varied from the wide side to the telephoto side while mixing real zoom and electronic zoom.

Other zooming methods include those shown by solid lines (01→02→0) and broken lines (0,→03→0). The former performs real zoom and then performs electronic zoom in the 51 state.
The latter is zooming in which electronic zoom is performed in a wide-angle state, and then real zoom is performed at the maximum electronic zoom.

J2 Here, if the magnification ratio of the electronic zoom is BEx, the magnification ratio of realism is Y311x, the focal length in the wide state during real zoom is f, and the 9 composite focal length is f (X), then f(
×) moves in conjunction with the magnification change of the real zoom, and is expressed by the following formula (%)) However, Xl, :1lo-1 indicates that the photographic lens is not moving. Note that the maximum variation from the wide state is normalized to 1. Further, (], +(Bt+1)X) in the formula indicates the outside of the real zoom magnification, and (1→(BE-1)X) indicates the outside of the electronic zoom. , Therefore, the cam protrusion (22) for moving the finder 1 nons
) is set so that the magnification is changed according to the above formula: % formula %)).

As described above, in this embodiment, the photographic lens is attached to the film (44) to be actually exposed, for example, from f-35mm to
While zooming to 105mm, the viewfinder is at f.35.
It is machined from mm to 210mm. Therefore, the photo equivalent to 105mm printed in the lab is taken by
The image was not exposed at the 105 mm lens, but was actually exposed at about 60 mm. This is different from the conventional example.

As explained above, the finder optical system corresponds to a predetermined range according to each zooming position of the photographing lens among the images formed on the photographing medium through the zoomable photographing lens. If the photographic lens is provided with means for enlarging the image to the full field frame at each zooming position of the photographic lens, and the means is configured to be driven by a drive system at the same time as the magnification change drive of the photographic lens. The movement of the lens and the movement of the lens of the finder optical system are performed at the same time, and the image corresponding to the predetermined range of the image formed on the photographic medium through the lens is expanded to the same extent as the field of view at each zooming position of the photographic lens. Because it is done,
With a simple configuration that does not require a dedicated actuator for the finder, it is possible to realize a finder optical system that can be made compact and at low cost.

Furthermore, it comprises an objective lens, an inversion optical system that inverts the image formed by the objective lens vertically and horizontally, and an eyepiece lens that guides the image described in 11j to the pupil, and the objective lens is driven by the means. With this configuration, the finder optical system can be easily linked with the photographic lens, making it possible to further reduce the size and cost.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a state in which a finder optical system and a photographic lens are connected according to the present invention, and FIG. 2 is a schematic diagram showing a cam barrel of the photographic lens. FIG. 3 is a graph showing the relationship between the magnification ratio and the composite focal length of the electronic zoom in the embodiment of the present invention, and FIG. 4 is a diagram for explaining the trimming system. (I)...finder section. (n)...Photographing lens section. (1)...Objective lens. (2)...G2 fixed part. (3)...Dach mirror (4)...Condenser L nons. (5)...prism. (6)...eyepieces. (7)...Pupillary surface. (9)...Gear. (10)...Motor. (19)...Gear. (20)...Cam barrel. (21)...Cam groove for moving the first lens group. (22)...-Cam protrusion for moving the finder lens. (23)...Cam groove for moving the 21st non-group. (30)...Fixed trunk. (31) . . . 1st Luns group fixing part. (32)...Second lens group fixing part. (41)...Luns group. (42)...Second lens group. (43)...Aperture. (44) (50)...Film. (A)...Trimming area.

Claims (2)

[Claims] (1) Among the images formed on the photographic medium through a zoomable photographic lens, the image corresponding to a predetermined range according to each zooming position of the photographic lens is expanded to fill the field of view at each zooming position of the photographic lens. 1. A finder optical system characterized in that said means is driven by a drive system at the same time as the magnification changing drive of said photographing lens. (2) It consists of an objective lens, an inversion optical system that inverts the image formed by the objective lens vertically and horizontally, and an eyepiece that guides the image to the pupil, and the objective lens is driven by the means. The finder optical system according to claim 1, characterized in that: