JPH0254225A - Optical system provided with optical path bending means - Google Patents

Abstract

PURPOSE:To effectively utilize the internal space of a camera and, simultaneously, to reduce the depth and size of the whole body of the camera by constituting a photographing system and finder system by providing a prism for elect normal images on the back of a 1st or 2nd reflecting mirror. CONSTITUTION:A photographing system is constituted of a photographing lens 11 and the 1st and 2nd reflecting mirrors M1 and M2. An objective lens 12 is provided in parallel with the photographing lens 11 and an object and the object lens 12, Porro prism 15, and eyepiece 14 constitute a part of a finder system. The Porro prism 15 used as a prism for elect normal images is provided on the back of the 1st reflecting mirror M1 so that one reflecting surface 15c inside the prism 15 can become almost parallel with the 1st reflecting mirror M1 of the photographing system. Therefore, the internal space of this camera can be utilized effectively and the whole body of the camera can be miniaturized.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an optical system having an optical path bending means, and particularly to a camera such as a photographic camera or a video camera, which has a finder system independent of the camera system. The present invention relates to an optical system having an optical path bending means suitable for reducing the vertical thickness of the camera and downsizing the camera as a whole.

(Prior Art) Conventionally, in the optical system of a single-lens reflex camera such as a photographic camera or a video camera, the photographing system is constructed by disposing a photosensitive surface 53 at the rear of the photographing lens 51 on the optical axis, as shown in FIG. are doing.

Further, the light beam passing through the photographing lens 51 is reflected upward of the camera body by a rotating mirror 52 disposed behind the photographing lens to form a finder image on the surface of the focusing plate 54. The finder system is configured such that the finder image on the surface of the focusing plate 54 is observed through the condenser lens 55 and the pentaprism 56 as an erect normal image with the eyepiece lens 57.

In this way, in some conventional reflex cameras, the viewfinder light beam is reflected to one side of the camera body by the rotating mirror 52,
A pentaprism placed above the photographic lens 51 is used to obtain an erect finer image. For this reason, the pentaprism, which is part of the components of the finder system, protrudes above the camera body, and when a photographic lens is attached to the camera body, the overall size of the camera tends to become relatively large. In particular, in a conventional configuration using a pentaprism, a portion of the camera protrudes, making it extremely difficult to reduce the thickness of the entire camera in the downward direction.

(Problems to be Solved by the Invention) The present invention does not use the conventional pentaprism, but by appropriately arranging a finder system having a plurality of reflecting mirrors as optical path bending means, the photographing system and the finder system can be combined as a whole. It is an object of the present invention to provide an optical system having an optical path bending means that can be efficiently housed in a thin space and can easily reduce the thickness and size of the entire camera.

(Means for solving the problem) Approximately 45 mm behind the photographic lens with respect to the optical axis of the photographic lens.
A first reflecting mirror arranged at approximately 45 degrees reflects the light beam passing through the photographic lens, and a second reflecting mirror arranged at approximately 45 degrees reflects the first reflected light beam reflected by the first reflecting mirror into the first reflected light beam.
A reflecting mirror substantially perpendicularly reflects the first plane formed by the optical axis of the photographic lens and the first reflected light beam, and the second reflected light beam reflected by the second reflecting mirror is directed onto a photosensitive surface. It has a photographing system configured to guide light, a finder system which is made up of an objective lens provided independently of the photographic lens, a prism for an erect image having a reflective surface, and an eyepiece, and is configured to observe a finder image of an erect image. However, the erecting normal image prism is arranged behind the first reflecting mirror or the second reflecting mirror.

(Embodiment) FIG. 1 is a plan view of a main part showing an optical path of a first embodiment of an optical system having an optical path bending means of the present invention. FIG. 2 is a front view of a portion of FIG. 1.

In the figure, reference numeral 11 denotes a photographing lens, and Ml denotes a first reflecting mirror, which is arranged at approximately 45 degrees with respect to the optical axis S1 of the photographic lens 11.
It is reflected in a direction perpendicular to the first reflected light beam Ll.

M2 is a second reflecting mirror, which is arranged at approximately 45 degrees with respect to the first reflected light beam L1, and converts the second reflected light beam L1 into a light beam on the optical axis of the photographing lens 11 and a first reflection of the light beam. The first reflected light beam L1 by the mirror M1 is reflected as a second reflected light beam L2 in a direction substantially perpendicular to the first plane formed by the first reflected light beam L1, and is guided to a photosensitive surface 13 of a film, CCD, or the like.

In this embodiment, the photographing lens 11 and the first and second reflecting mirrors M1.
The photographing system is composed of M2.

Reference numeral 12 denotes an objective lens, which is arranged parallel to the photographing lens 11 and the subject.

Reference numeral 15 designates a Porro prism as a prism for erecting an erect image, a part of which is formed with an inverted finder image by the objective lens 12, and the inverted finder image is converted into an erect image and emitted.

That is, the Porro prism 15 receives the light beam L3 from the objective lens 12.
The light is reflected above the camera by a reflective surface 15a, and then sequentially reflected by two reflective surfaces 15b and 15c disposed orthogonally to each other, and then emitted from the Porro prism 15.

Reference numeral 14 denotes an eyepiece lens through which an erect viewfinder image converted by a Porro prism 15 is observed.

Objective lens 12, Porro prism 15. The eyepiece lens 14 constitutes a part of the finder system.

In this embodiment, the Porro prism 15 is arranged behind the first reflecting mirror Ml so that one reflecting surface 15c within the Porro prism 15 is substantially parallel to the first reflecting surface 111MI of the photographing system.

This allows for effective use of the space inside the camera, thereby reducing the overall size of the camera.

FIG. 3 is a plan view of the main part showing the optical path of the second embodiment of the present invention;
FIG. 4 is a front view of a portion of FIG. 3; Elements that are the same as those shown in the first embodiment of FIG. 2 are given the same reference numerals.

This embodiment has the same configuration of the photographing system as the first embodiment shown in FIGS. 1 and 2, but differs from the first embodiment in a part of the configuration of the finder system.

In this embodiment, the light beam L3 from the objective lens 12 is sequentially reflected by two reflecting surfaces 15a and 15b disposed perpendicularly to each other and guided downward to the camera, and then guided to the lower part of the camera.
The light is reflected by the beam and emitted from the Porro prism 15.

This converts an inverted finder image formed by the objective lens 12 into an upright finder image. The light beam L3 is guided to the eyepiece 13, and an erect finder image is observed through the eyepiece 14.

In this embodiment, the Porro prism 15 is arranged such that the line lO connecting the point of incidence 15d of the light beam L3 on the optical axis of the finder system to the Porro prism 15a and the point of exit 15e is approximately parallel to the second reflecting surface M2 of the photographing system. is arranged behind the second reflecting mirror M2.

In this embodiment, there are first lenses on both sides of the imaging system. The finder systems shown in FIG. 3 may be arranged individually, and in this way a binocular finder with a simple configuration can be achieved.

In the finder system in this embodiment, each element is set so that the optical axis Sl of the photographing lens and the optical axis S2 of the finder system are approximately parallel to facilitate observation of the finder image, but they are configured to be tilted. In this embodiment, it is preferable to arrange a light shielding member, such as a focal brain shutter, on the photosensitive surface 13 to prevent undesirable light from entering the photosensitive surface 13 when observing the finder image.

Furthermore, in the present invention, when the reversely incident light from the eyepiece side of the finder system reaches the photosensitive surface 13 during photographing, a member 5 such as an eyepiece shutter for blocking the reversely incident light is provided in a part of the finder system. is good.

(Effects of the Invention) According to the present invention, by configuring the photographing system and finder system as described above, it is possible to effectively utilize the space inside the camera, and to create an optical system with a simple structure that makes the entire camera thin and compact. , has been achieved. Furthermore, if the finder system is placed on both sides of the photographing system, a binocular finder system can be easily achieved.

[Brief explanation of the drawing]

FIGS. 1 and 2 are plan views and front views of essential parts showing the optical path of the first embodiment of the present invention, and FIGS. 3 and 4 are plan views of essential parts showing the optical path of the second embodiment of the present invention. and a front view, and FIG. 5 is a schematic diagram of the optical system of a conventional single-lens reflex camera. In the figure, 11 is a photographing lens, Ml is a first reflecting mirror, M2 is a second reflecting mirror, 13 is a photosensitive surface, 12 is an objective lens, 15 is a Porro prism, 14 is an eyepiece, and 15a, 15b, and 15c are reflecting surfaces. be.

Claims (3)

[Claims] (1) A first reflecting mirror placed behind the taking lens at approximately 45 degrees with respect to the optical axis of the taking lens reflects the light flux that has passed through the taking lens, and the first reflection is reflected by the first reflecting mirror. The light beam is reflected in a direction substantially perpendicular to a first plane formed by the optical axis of the photographing lens and the first reflected light beam by a second reflecting mirror arranged at approximately 45 degrees with respect to the first reflected light beam. , a photographing system configured to guide a second reflected light beam reflected by the second reflecting mirror onto a photosensitive surface, an objective lens provided independently of the photographing lens, an erecting normal image prism having a reflective surface, and an eyepiece. and a finder system configured to observe a finder image of the erected normal image, and the prism for the erected normal image is arranged behind the first reflecting mirror or the second reflecting mirror. An optical system having an optical path bending means. (2) The optical path bending means according to claim 1, wherein the erecting normal image prism is configured such that one reflecting surface thereof is substantially parallel to the reflecting surface of the first reflecting mirror. An optical system with (3) A line connecting the point of incidence and the point of exit of the light beam on the optical axis of the finder system into the erecting image prism is
2. An optical system having an optical path bending means according to claim 1, wherein the optical system is configured to be substantially parallel to a reflecting surface of a reflecting mirror.