JPH04191829A - Finder and photographing optical system - Google Patents

Abstract

PURPOSE:To eliminate parallax at the observing time of an object by observing the object by extracting a finder luminous flux from a photographing optical system at the observing time of the object on a long focal distance side. CONSTITUTION:Variable power is executed by a photographing system A by mutually changing an interval between a first lens group 1, and a second lens group 2. Besides, the photographing system A has a property that back focus on the short focal distance side thereof is short and the back focus on the long focal distance side is long on the contrary. That means, by arranging a reflecting member 3 such as a plane mirror at the part of the back focus side at the observing time of a finder in the case that the photographing of the long focal distance is executed, a photographing luminous flux from the photographing system A can be guided to the real image surface 9 of a finder system. Thus, the parallax whose tendency becomes remarkable on the long focal distance side of a compact camera where in variable power can be executed is reduced or eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a finder/photographing optical system integrated with a photographing system in a silver halide camera, an electronic video camera, or the like.

(Prior Art) Conventionally, methods for extracting the finder light flux from the photographing system include, for example, placing a beam splitter in the middle of the photographing system, as in the case of an 8 mm camera or video camera, or using a normal beam splitter. A known method is to place a quick return mirror behind the optical system, as in the case of a single-lens reflex camera.

Furthermore, in the past, various methods have been proposed in which a reflecting member is used to divide the photographing optical path and the finder optical path in order to eliminate finder parallax when extracting the finder light beam from the photographing system.

The main example is:

(2) As described in US Pat. No. 4,838,668, a method of extracting the finder light beam by providing a space for a reflective member within the zoom lens group.

(2) As described in Japanese Unexamined Patent Publication No. 2-59735, a method of moving a part of the photographing system and inserting a reflecting member therein to take out the finder light flux.

(2) As described in Japanese Patent Application Laid-open No. 2-16532, a method in which two reflecting members are provided in a part of the finder system to guide the finder light beam to the photographing system.

etc. are known.

(Problem to be Solved by the Invention) By the way, many conventional compact cameras (generally many cameras with a single lens/shutter type) have a finder optical system separate from the photographic optical system, and each of these optical systems Since the optical axes are offset from each other, the closer the subject is, the more the shooting range and the viewfinder's field of view become misaligned, making accurate framing impossible.

The 29mm is called vararax, and has traditionally been a major drawback in compact cameras.

This tendency is particularly noticeable on the long focal length side of recent cameras with variable magnification.

Because of this, this vararax is reduced or.

Solving this problem has traditionally been a major challenge in this type of optical system.

Conventionally, a so-called -eye reflex camera is an example of a camera that has been able to eliminate this variation.

However, as is well known, this eye reflex camera
A quick return mirror is disposed between the photographing lens system and the film surface to take out the finder light beam.

For this reason, in conventional single-lens reflex cameras, it is necessary to secure enough space near the film surface for the quick return mirror to be able to move at all times, and because the quick return mirror itself is large, There was a problem that made it unsuitable for cameras that require compactness.

Also, like optical systems for cameras and video cameras,
There is a method in which a beam splitter is placed in the optical system to collect the finder light flux, but this method requires space to place the beam splitter in the optical system. The disadvantage is that the lens length of the optical system becomes longer, making the entire camera larger.

On the other hand, as described in Japanese Patent Application Laid-Open No. 2-59735, there is a conventional method in which a part of the photographing system is moved and a reflecting member (optical path splitting member) is inserted therein to take out the finder light beam. can be applied to a photographing lens with a single focal length, but cannot be applied to a variable magnification lens.

Furthermore, as described in US Pat. No. 4,838,668, in the method of extracting the finder light flux by providing a space for a reflective member within the zoom lens group, the finder light flux is always extracted from the same position in the photographing system. , the conditions for creating that space are imposed on the photographing system, which poses the problem of complicating the lens configuration of this photographing system.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide a compact camera that has a variable magnification function, but that does not take away the finder light flux from its photographic optical system. The object of the present invention is to provide a finder/photographing optical system that can eliminate parallax while preventing the camera from increasing in size.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention performs zooming by moving a plurality of lens groups along the optical axis and changing the intervals between these lens groups. A photographing system, a real image zoom finder system having an erect regular image reflection system between the objective lens system and the eyepiece system, and a real image zoom finder system which is arranged to be movable forward and backward with respect to the photographing optical path in the space on the imaging plane side of the photographing system. a first reflective member;
A reduction lens that reduces the photographing light flux from the photographing system reflected by the first reflecting member, and a reduction lens arranged to be able to move forward and backward with respect to the finder optical path between the reduction lens and the real image plane of the erecting normal image reflection system. When photographing and observing on the short focal length side, the first reflecting member is retracted from the photographing optical path on the imaging plane side of the photographing system, and the second reflecting member is removed from the photographing system. The camera takes pictures of the subject by guiding the photographing light beam to the imaging plane.

A second reflecting member is advanced into the finder optical path between the reducing lens and the real image plane of the erecting normal image reflecting system, and the second reflecting member allows the light incident from the objective lens system of the real image zoom finder system to be reflected. By guiding the finder light flux to the real image plane of the erect regular image reflection system, the object is observed using the real image zoom finder system that is independent from this photographing system, and when shooting at a long focal length, the photographing is performed as described above. A first reflecting member is advanced into the photographing optical path on the imaging plane side of the system, and a second reflecting member is retracted from the finder optical path between the reduction lens and the real image plane of the erecting normal image reflecting system, The photographing light beam from the photographing system in which the lens group is located on the short focal length side is reflected by the first reflecting member and reduced by the reduction lens, and then this photographing light beam is converted into a real image of the erecting normal image reflecting system. The object is observed by guiding the object to the long focal length side, and when photographing at the long focal length side, the plurality of lens groups of the photographing system are positioned on the original long focal length side when observing at the long focal length side. 5. The object is photographed by retracting the first reflecting member from the photographing optical path on the imaging plane side of the photographing system and guiding the photographing light beam from the photographing system to the imaging plane.

(Function) According to the present invention, during photographing and observation on the short focal length side, the first reflecting member is retracted from the photographing optical path on the imaging plane side of the photographing system, and the photographing light beam from the photographing system is is guided to the imaging plane to photograph the subject, and a second reflecting member is advanced into the dark finder optical path between the reduction lens and the real image plane of the erecting normal image reflection system, and the second reflecting member By guiding the finder light flux incident from the objective lens system of the real image zoom finder system to the real image plane of the erect normal image reflecting system by the reflecting member, the real image zoom finder system independent from this imaging system Observation of the subject is performed.

According to one aspect of the present invention, Il! on the long focal length side! At the time of observation, a first reflecting member is advanced into the photographing optical path on the imaging plane side of the photographing system, and a second reflective member is advanced from the finder optical path between the reduction lens and the real image plane of the erecting normal image reflecting system. After the member is retracted and the photographing light beam from the photographing system in which the plurality of lens groups are positioned on the short focal length side is reflected by the first reflecting member and reduced by the reduction lens, this photographing light beam is The object is observed by being guided to the real image plane of the erected image reflection system.

Furthermore, according to the present invention, when photographing on the long focal length side, the plurality of lens groups of the photographing system during flR observation on the long focal length side are located on the original long focal length side, and The first reflecting member is retracted from the photographing optical path on the imaging surface side of the photographing system.

The subject is photographed by guiding the photographing light beam from the photographing system to the imaging plane.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

However, in order to avoid complicating the explanation, illustrations and disclosures thereof will be omitted to avoid complicating the explanation, as well as the configuration and operation within the range that can be clearly recalled from the description of this specification, as well as the above-mentioned and other objects and novel features of the present invention. , or simplify it.

The viewfinder/photographing optical system according to the present invention focuses on the fact that the influence of balarax is generally greater on the long focal length side of the photographic optical system. It is characterized by extracting a luminous flux and eliminating the variation while smoothly combining it with the movement of the photographing optical system.

The finder/photographing optical system according to the present invention, as shown in FIG. , an erect regular image reflection system is provided between the objective lens system B and the eyepiece system C, and is arranged so as to be able to move forward and backward with respect to the photographing optical path in the space on the imaging plane side of the real image zoom finder system E and the photographing system A. A first reflecting member 3 provided, a reducing lens 12 that reduces the photographing light beam from the photographing system A reflected by the first reflecting member 3, and a real image of the reducing lens 12 and the erect normal image reflecting system. A second reflecting member 8 is disposed so as to be movable forward and backward with respect to the finder optical path between it and the surface 9.

As shown in FIG. 2, the photographing system A is composed of two positive and negative zoom lens groups each having an aperture 13 disposed between a first lens group 1 and a second lens group 2. Often used in lens-shutter compact cameras.

On the other hand, objective lens system B of real image zoom finder system E
is composed of objective lens groups 5 and 6 of a real image zoom finder system.

Also, the eyepiece system C of the real image zoom finder system E
is composed of an eyepiece lens group 11.

Further, the erecting regular image reflection system of the real image zoom finder system E focuses the finder light beam from the objective lens system B, which is refracted by the second reflection member 8 made of a plane mirror, on the real image plane 9 of the finder system. It consists of a condenser lens 10 and a prism 7 that guides the object image formed on the real image plane 9 of the finder system to the eyepiece system C as an erect image.

By the way, in this type of imaging system A, as is well known, the first
The magnification is changed by changing the distance between the lens group 1 and the second lens group 2.

In this type of photographing system A, as shown in Fig. 2(,), the back focus on the short focal length side is short, but on the other hand, as shown in Fig. 2(b), the back focus on the long focal length side is short. It has the property of having a long back focus on the sides.

Therefore, when observing IR on the long focal length side of the photographing system A, it is possible to secure a sufficient space for arranging a reflective member such as a plane mirror on the back focus side.

That is, when observing through the finder when photographing at a long focal length, this photographing system A is
It is possible to guide the photographing light beam from the camera to the real image plane 9 of the finder system.

As a result, it is possible to reduce or eliminate the variation that tends to become more pronounced on the long focal length side of recent compact cameras capable of variable magnification.

On the other hand, if the incident angles are the same, the corresponding image height will naturally be smaller at a short focal length than at a long focal length.

Taking advantage of this, when observing through the finder when photographing with a long focal length, each lens group 1 and 2 of photographing system A is arranged so that the focal length is shorter than the actual photographing focal length. As a result, the photographing light beam from the photographing system A that is guided to the real image plane 9 of the finder system becomes a small image.

As a result, the image formed on the real image plane 9 of the finder system becomes a small image, so that the finder system can be configured compactly.

Therefore, according to this embodiment, it is a compact camera,
In addition, even though the camera has a variable magnification function, it is possible to remove the finder light flux from the photographing optical system and eliminate the variation while preventing the camera from increasing in size.

That is, when photographing and observing on the short focal length side of the finder/photographing optical system in this embodiment, as shown in FIGS. 1 and 4, the photographing optical path 0 on the imaging plane 4 side of the photographing system A
1 to the first reflecting member 3 is retracted, and the photographing light beam from the photographing system A is guided to the imaging plane 4 to photograph the subject, and the real image of the reduction lens 12 and the erect normal image reflection system is A second reflecting member 8 is advanced into the finder optical path 02 between the surface 9 and the finder light beam 02 incident from the objective lens system B of the real image zoom finder system E, and the finder light beam 02 incident from the objective lens system B of the real image zoom finder system E is reflected by the second reflecting member 8. The subject (
(not shown) are observed.

In addition, when observing on the long focal length side of the finder/photographing optical system in this embodiment, as shown in FIGS. 3 and 5, a first As the reflection member 3 is advanced, the finder optical path 02 between the reduction lens 12 and the real image plane 9 of the erecting normal image reflection system
The second reflecting member 8 is retracted from the first. After the photographing light beam from the photographing system A in which the second plurality of lens groups 1 and 2 are located on the short focal length side is reflected by the first reflecting member 3 and further reduced by the reduction lens 12, this photographing light beam is The object is observed by guiding the ○□ to the real image plane 9 of the erect normal image reflection system.

Furthermore, when photographing on the long focal length side of the finder/photographing optical system in this embodiment, as shown in FIG.
．． The second plurality of lens groups 1゜2 are positioned on the original long focal length side, and the first reflecting member 3 is retracted from the photographing optical path O□ on the imaging plane 4 side of this photographing system A. Photography system A
The subject is photographed by guiding the photographing light beam from the camera to the imaging plane 4.

(Effects of the Invention) According to the present invention, when observing a subject at the long focal length side where the influence of vararax is most noticeable, it is possible to take out the finder light flux from the photographing optical system and observe the subject. It is possible to eliminate the variation during wll waiting.

Furthermore, according to the present invention, the reflecting member for extracting the finder light beam from the photographing optical system is advanced into the space created by the movement of the zoom lens group of the photographing system, which reduces the design burden on the photographing system. It is possible to realize a compact camera that prevents the camera from increasing in size, even though it has a variable magnification function without increasing the size of the camera.

Furthermore, according to the present invention, when observing a subject by taking out the finder light flux from the photographing optical system, by arranging the photographing system so that the focal length is shorter than the actual photographing focal length, Since the photographing light beam from this photographing system guided to the real image plane of the finder system can be made into a small image, the eyepiece system used for observation at the short focal length side can be used as is, and at this time, The area of the reflecting member can be small, and
The retraction space for this reflective member can also be reduced.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view of the optical system when photographing at the short focal length side and observing through the finder in the embodiment of the present invention;
The figure is a schematic side view of the zoom lens group of the photographing system in the above embodiment, FIG. 3 is a schematic perspective view of the optical system during viewfinder observation on the long focal length side in the above embodiment, and FIG. 4 is a schematic side view of the zoom lens group of the photographing system in the above embodiment. A schematic side view of the optical system when photographing on the short focal length side and observing through the finder, FIG. 5 is a schematic side view of the optical system when observing through the finder on the long focal length side in the above embodiment, and FIG. 6 shows the above FIG. 3 is a schematic side view of the optical system during photographing on the long focal length side in the example. 1... First lens group, 2... Second lens group, 3
...first reflecting member, 4...imaging surface, 5.6...
Objective lens group, 7... Prism, 8... Second reflecting member, 9... Real image plane of finder system, 10... Condenser lens, 11... Eyepiece lens group, 12...
・Reduction lens, 13...Aperture, A...Photography system, B.
...Objective lens system, C...Eyepiece system, D...Erection normal image reflection system, E...Real image zoom finder system,
01...Photographing optical path, 02...Finder (and 1 more)
Name) Kan 2 figure r? i'?

Claims (1)

[Claims] An imaging system that changes magnification by moving a plurality of lens groups along an optical axis and changing the spacing between these lens groups, and an erect lens system between an objective lens system and an eyepiece lens system. a real-image zoom finder system having an image reflection system; a first reflection member disposed so as to be movable forward and backward with respect to the photographing optical path in the space on the imaging plane side of the photographing system; a reduction lens for reducing the photographing light beam from the photographing system; and a second reflection member disposed so as to be movable forward and backward with respect to the finder optical path between the reduction lens and the real image plane of the erecting normal image reflection system. When photographing and observing on the short focal length side, the first reflecting member is retracted from the photographing optical path on the imaging plane side of the photographing system, and the photographing light beam from the photographing system is directed to the imaging plane. At the same time, a second reflective member is advanced into the finder optical path between the reduction lens and the real image plane of the erecting regular image reflection system, and the second reflection member is used to capture the real image. By guiding the finder light flux incident from the objective lens system of the zoom finder system to the real image plane of the erecting regular image reflection system, the subject is observed by the real image zoom finder system, which is independent from this imaging system, and the object is observed at a long focal point. During observation on the distance side, the first reflecting member is advanced into the imaging optical path on the imaging plane side of the imaging system, and the first reflecting member is moved from the finder optical path between the reduction lens and the real image plane of the erecting regular image reflection system. After the second reflecting member is retracted and a plurality of lens groups are positioned on the short focal length side, the photographing light beam from the photographing system is reflected by the first reflecting member and reduced by the reduction lens. The object is observed by directing the image to the real image plane of the erect image reflection system, and when photographing at the long focal length side, the multiple lens groups of the photographing system at the time of observation at the long focal length side are At the same time, the first reflecting member is retracted from the imaging optical path on the imaging surface side of the imaging system to guide the imaging light flux from the imaging system to the imaging surface, thereby photographing the subject. A finder/photography optical system that is characterized by the ability to: