JPH04245233A - Ttl finder system - Google Patents

Abstract

PURPOSE:To provide a TTL finder system, which enables designing the whole camera construction in small size and with small wall thickness using a plurality of mirrors wherein the light flux having passed through a photographing lens is set properly. CONSTITUTION:The light flux having passed through a photographing lens 2 is reflected in the direction perpendicular to the optical axis by No.1 mirror 3 rotatable, reflected in the direction parallel with the optical axis by No.2 mirror 7, reflected in the direction perpendicular to the optical axis by a No.3 mirror 9 upon allowing it to pass behind a photo-sensitive part 13 on which an object image is formed by the photographing lens, and reflected in the direction parallel with the optical axis by a No.4 mirror 11, and then it is led to an eyepiece lens 12. Through this lens 12, it is possible to observe the object image formed by the photographing lens.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a TTL finder system, and is particularly suitable for reducing the vertical thickness of a camera such as a photographic camera or a video camera, thereby reducing the overall size of the camera. It is related to.

0002

2. Description of the Related Art Conventionally, in a TTL finder system in a single-lens reflex camera such as a photographic camera or a video camera, for example, in a TTL finder system having a secondary imaging system, a photographing lens (zoom lens) 2 is used as shown in FIG. A rotating mirror 3a is arranged behind the photographing lens so that the light flux that has passed through the
The focus plate 6a is reflected upward from the camera body 1a.
An object image (finder image) is formed on the surface. The finder image on the focusing plate 6a is then converted into an erect image via the mirror 7a and the erector system 8, and the finder image at this time is transferred via the field lens 10 to the eyepiece 1.
2, I try to observe from eye point 15. Reference numeral 13 denotes a photosensitive portion (film surface), which is pressed against a pressure plate 14.

In addition, in a single-lens reflex camera for 35 mm film, a rotating mirror reflects the viewfinder light flux above the camera body, and a pentaprism placed above the photographic lens is used to obtain an erect viewfinder image. . This finder image is then observed through an eyepiece.

0004

In the optical system shown in FIG. 2, the light beam from the photographing lens 2 is reflected above the camera body 1a by a rotating mirror 3a and guided to a finder system at the top of the camera. For this reason, there was a tendency for the upper part of the camera to become thicker. In addition, in a single-lens reflex camera for 35 mm film, a pentaprism, which is part of the components of the finder system, protrudes above the camera body. For this reason, when a conventional photographic lens is attached to a camera body, the entire camera tends to become relatively large. In particular, in the conventional configuration using a pentaprism, a portion of the camera has a protruding shape, making it extremely difficult to reduce the thickness of the entire camera in the vertical direction.

The present invention provides a TTL finder system that efficiently stores the entire finder system in a thin space by appropriately arranging a plurality of mirrors near the photosensitive section, thereby making the entire camera thin and compact. The purpose is to provide.

[0006]

[Means for Solving the Problems] In the TTL finder system of the present invention, a light beam passing through a photographing lens is sequentially reflected in a direction approximately perpendicular to the optical axis by a rotatable first mirror, and a second mirror is used to reflect a light beam approximately perpendicular to the optical axis. It is reflected in a parallel direction, passes behind the photosensitive section that forms an object image by the photographing lens by a third mirror, is reflected in a direction substantially perpendicular to the optical axis, and is reflected in a direction substantially parallel to the optical axis by a fourth mirror. After that, the light is guided to an eyepiece lens, and the object image formed by the photographic lens is observed through the eyepiece lens.

In addition, in the present invention, a focusing plate is disposed between the first mirror and the second mirror, an object image is formed on the focusing plate surface by the taking lens, and an object image on the focusing plate surface is formed. The object is re-imaged by an erector system, and the re-imaged object image is observed through an eyepiece.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram of essential parts of an optical system according to an embodiment of the present invention.

In the figure, 1 is the camera body, 2 is the photographing lens, which includes a focusing lens group F for focusing, a variable magnification lens group V for zooming, an aperture SP, and a lens that corrects the image plane that changes with zooming. It consists of a zoom lens consisting of a correction lens group C for the purpose of Reference numeral 3 denotes a rotatable first mirror, which is rotated in the direction of arrow 3a about a fulcrum 3b by a known quick return mechanism (not shown). The first mirror 3 reflects the light beam from the photographic lens system 2 in a direction substantially perpendicular to the optical axis L of the photographic lens system 2. A part of the first mirror 3 on the optical axis is a semi-transparent part, and the light beam passing through the semi-transparent part is reflected by the sub-mirror 4 fixed to the first mirror 3 and enters the automatic focus detection device 5. ing. The automatic focus detection device 5 is constructed using a known detection method and detects the focal position (focus position) of the photographic lens 2.

Reference numeral 13 denotes a photosensitive section, which is made up of an imaging device such as a film or CCD, and is pressed against a pressure plate 14. A slit-traveling type shutter means (not shown) is provided in front of the photosensitive section 13 to limit the amount of light passing therethrough.

Reference numeral 6 denotes a focusing plate, on whose surface a first object image formed by the photographing lens 2 is formed after being reflected by the first mirror 3.

A second mirror 7 reflects the light beam based on the first object image formed on the surface of the focusing plate 6 in a direction substantially parallel to the optical axis L, and guides it to the erector system 8. 9 is the third
It is a mirror that directs the light beam from the erector system 8 to the photosensitive section 13.
The light is reflected behind the optical axis L in a direction substantially orthogonal to the optical axis L. The erector system 8 forms a second object image near the field lens 10 via the third mirror 9 from the first object image on the focusing plate 6 surface.

A fourth mirror 11 reflects the light beam from the second object image formed near the field lens 10 in a direction substantially parallel to the optical axis and guides it to the eyepiece lens 12. A second object image formed near the field lens 10 by the eyepiece 12 is observed from the eyepoint 15.

In this embodiment, as described above, the light beam from the photographing lens 2 is reflected by the first mirror 3 to form a first object image on the surface of the focusing plate 6. and the first one on the 6th surface of the focusing plate.
The object image is reflected by a second mirror 7 and guided to an erector system 8. Then, the third mirror 9 is set by the erector system 8.
A second object image (aerial image) is formed near the field lens 10 via the field lens 10. Then, the second object image near the field lens 10 is transmitted to the eyepiece lens 12 via the fourth mirror 11.
I am observing it.

At this time, in this embodiment, the first to fourth mirrors,
The focusing plate 6, the erector system 8, the field lens 10, and other elements are arranged so as to surround the photosensitive section 13 as described above, thereby reducing the length in the optical axis direction by LL2 compared to the conventional optical system shown in FIG. The length is shortened to LL1, and the length in the direction perpendicular to the optical axis is also shortened to effectively make the entire photographing system, that is, the entire camera, thin and compact.

In this embodiment, the first mirror 3 reflects the light beam above the camera instead of below the camera.
Each element from the first mirror to the eyepiece may be arranged symmetrically with respect to the optical axis L.

In this embodiment, the reflection of the light beam in a substantially vertical direction does not necessarily have to be strictly vertical, and may mean, for example, within ±20 degrees with respect to the vertical direction. The same applies to the substantially parallel direction.

[0018]

According to the present invention, the thickness of the finder system as a whole can be reduced by appropriately arranging each element such as a plurality of mirrors, a focus plate, an erector system, and a field lens near the photosensitive area as described above. It is possible to achieve a TTL finder system that can be efficiently housed in a thin space, and the entire camera can be made thinner and smaller.

[Brief explanation of the drawing]

FIG. 1: Schematic diagram of main parts of an embodiment of the present invention

[Fig. 2] Schematic diagram of main parts of a conventional imaging system with a secondary imaging system

[Explanation of symbols]

1 Camera body 2 Photographic lens system 3 First mirror 4 Sub mirror 5 Automatic focus detection device 6 Focus board 7 Second mirror 8 Erecta type 9 Third mirror 10 Field lens 11 4th mirror 12 Eyepiece lens

Claims (2)

[Claims] Claim 1: A light beam passing through a photographic lens is reflected in a direction approximately perpendicular to the optical axis by a first rotatable mirror, and a second mirror is rotated.
A mirror reflects the light in a direction substantially parallel to the optical axis, a third mirror passes behind the photosensitive section that forms an object image using the photographing lens, the light is reflected in a direction substantially perpendicular to the optical axis, and a fourth mirror reflects the light in a direction substantially parallel to the optical axis. A TTL finder system characterized in that the light is reflected in a direction substantially parallel to the , and then guided to an eyepiece, and an object image formed by the photographic lens is observed through the eyepiece. 2. A focusing plate is disposed between the first mirror and the second mirror, an object image is formed on the focusing plate surface by the photographing lens, and the object image on the focusing plate surface is transferred to an erector system. 2. The TTL finder system according to claim 1, wherein the object image is re-imaged by the eyepiece lens.