JPH0750289B2 - Eye level / waist level combined finder - Google Patents

Description

The present invention relates to an eye level / waist level combined finder using a reflective optical system.

[Prior art]

Conventionally, the eye level and waist level combined finder is well known. For example, Japanese Examined Patent Publication No. 59-11089 discloses a technique in which an erect image can be seen in both finder systems. The technique disclosed in this publication is shown in FIG. The eye level finder system is basically composed of an objective lens 1 and a convex eye level eyepiece. In the waist level finder system, the semi-transparent mirror 4 is arranged in the optical path of the eye level finder, and the semi-transmissive light from the semi-transparent mirror 4 is received by the total reflection mirror 5 and the eyepiece 3 for the waist level to reach the waist level. It is configured to guide the light flux.

However, since the light beam is divided into the eye level and the waist level by using the semi-transparent mirror 4, there is a problem when both the finder systems become dark.

[Object of the Invention]

An object of the present invention is to solve the above problems and provide a finder that can see a bright erect image when used at the waist level and at the eye level.

In order to achieve the above-mentioned object, a first entrance portion that guides a subject light flux to an eye level, a second entrance portion between waist levels different from the first entrance portion, and a second entrance portion from the second entrance portion are provided. It is provided with a prism having a roof surface that guides light to a waist level and an erect image can be observed.

〔Example〕

FIG. 1 shows a first embodiment of the present invention. FIG. 1 (a) is a perspective view, FIG. 1 (b) is a sectional view, and FIG. 1 (c).
Is a view seen from the eye level direction. 6 is an objective lens,
Reference numeral 7 is a roof prism that guides the light flux to the waist level.
The roof prism has reflecting surfaces 7c and 7d, a plane 7a which is a plane perpendicular to the optical axis of the objective lens 6, and a surface 7b which is parallel to this plane. The Dach ridge line 7e forms an angle of 45 ° with the optical axis of the objective lens. Reference numeral 8 is a condenser lens. The condenser lens is arranged near the image forming point of the objective lens and also serves as an eyepiece lens.

According to such a structure, in the waist level finder system, first, the field ray passing through the objective lens 6 is switched left and right by the double reflection on the roof surfaces 7c and 7d of the roof prism 7. At the same time, they are propagated upward by 90 ° to form an erect normal image in the vicinity of the condenser lens 8 and are efficiently collected by the condenser lens 8 in the eyepoint direction at a relatively distant position. That is, a bright field image of an erect image can be seen at a sufficiently long eyepoint position. Further, as an eye level finder system, a part 7a of the plane 7a of the roof prism 7 is used.
₁ is an entrance portion for the eye level, and a part 7b ₁ of a plane 7b on the optical axis of the eye level and parallel to the entrance surface 7a is configured as the exit surface of the eye level finder. That is, the field ray can be observed as a bright image of an erect image.

As described above, the light fluxes of both the viewfinders before entering the prism are substantially parallel, and the prism receives light from a distant subject, so that the same image is observed in both viewfinders.

Next, an embodiment obtained by developing the above embodiment will be described.

FIG. 2 shows the eye level entrance 7a _{1 in the} roof prism 7.
Is a concave surface on the object side, and the eye-level emitting portion 7b ₁ is a convex surface on the eye-point side, thereby expanding the degree of freedom in selecting the field of view and image magnification as an eye-level finder. Further, the waist level finder objective lens 6 is integrally formed with the roof prism 7.

In other words, regarding the eye level finder system, if the eye level entrance portion 7a ₁ and the eye level exit surface 7b ₁ are such curved surfaces, they become lens surfaces having negative and positive refracting power, respectively, and become a reverse rheotype finder. The field of view is obtained. Further, regarding the waist level finder system, integrating the objective lens 6 and the roof prism 7 has an advantage that a lens barrel member for holding the objective lens is not necessary and the assembling process can be simplified. Here, the condenser lens 8 may be a Fresnel lens. If a Fresnel lens is used, the thickness of the condenser lens can be reduced, and the finder as a whole can be made smaller accordingly. Of course, the condenser lens 8 may be integrated with the roof prism 7.

FIG. 3 is a sectional view of the finder system showing the numerical embodiment 1. A concave lens 10 is arranged in the eye level finder system on the object side of the eye level entrance portion 7a ₁ of the roof prism 7 to provide a wider field of view. Thus, as the eye level finder system, a concave lens is provided on the object side of the roof prism 7,
It is also possible to arrange a convex lens or the like on the eyepoint side to change the visual field range and visual field magnification.

Next, FIG. 4 is a sectional view of the finder system of the present invention shown in Numerical Embodiment 2. The eye level finder system is a reversal leo-style albada hua wonder. In this example the eye-level injection unit 7b ₁ R ₄ of the roof prism 7 and the concave half mirror surface, allowing observation of the field of view frame arranged frame reflector R ₅ -R ₆ between this surface and the eyepiece. Further, in the waist level finder system, the objective lens is composed of two lenses to obtain a good visual field image, and it is possible to make the front surface of the objective lens small. Although one Fresnel lens is used as the condenser lens, the condenser lens may be composed of a plurality of lenses.

In the above embodiment, the angle between the ridge line 7e of the roof and the optical axis of the objective lens is set to 45 °, and the optical axis of the objective lens is bent upward by 90 °, but it is not necessarily 90 ° and other angles are not necessary. But good. Generally, when the angle is smaller than 45 °, the angle at which the finder is seen is between the waist level and the eye level, which is preferable on the angle, but since the roof prism is enlarged, the inclination of the roof edge of the roof to the optical axis of the objective lens is 10 °.
It is desirable to make it above. Also, it is desirable to place the condenser lens near the image formation point of the objective lens in order to downsize the condenser lens, but by changing the relative position of the image formation point and the condenser lens, the field of view at the waist level, The field of view magnification can be changed.

Numerical examples will be shown below.

Numerical Example 1 Eye level finder system 2ω = 51.9 R1 = −38.39 D1 = 1.5 N1 = 1.49171 V1 = 57.4 R2 = 10.30 D2 = general formula 0 R3 = −98.77 D3 = 20.5 N2 = 1.49171 V2 = 57.4 R4 = −16.48 waist Level finder system 2ω = 51.9 r1 = 13.0 d1 = 31.5 n1 = 1.49171 ν1 = 57.4 r2 = ∞ d2 = 1 n2 = 1.62299 ν2 = 58.2 r3 = 40.0 d3 = 5.8 r4 = −30.0 Numerical Example 2 Eye level finder system 2ω = 49.5 ° R1 = ∞ D1 = 1.0 N1 = 1.50137 νd = 56.4 R2 = 13.50 D2 = 2.5 R3 = ∞ D3 = 14.8 N2 = 1.50137 νd = 56.4 R4 = 33.06 D4 = 9.8 R5 = ∞ D5 = 1.0 N3 = 1.523 νd = 58.6 R6 ＝ ∞ D6 ＝ 1.0 R7 ＝ 37.94 D7 ＝ 2.0 N4 ＝ 1.50137 νd ＝ 56.4 R8 ＝ －37.94 Waist level finder system 2ω ＝ 49.5 ° r1 ＝ －26.68 d1 ＝ 8.0 n1 ＝ 1.5927 νd ＝ 56.4 r2 ＝ 019.53 d2 ＝ 0.15 r3 = 15.05 d3 = 32.5 n2 = 1.50137 νd = 56.4 r4 = ∞ d4 = 1.4 r5 = Fresnel surface d5 = 1.5 n3 = 1.49171 νd = 5
7.4 r6 = ∞ The shape of the Fresnel surface is a Fresnel convex lens surface, and the spherical lens equivalent focal length f is f = 22.7 Ri, ri is the radius of curvature Di, di is the lens surface vertex spacing or air spacing Ni, ni, Vi, νi are optical elements Refractive index and Abbe's number [Effect] As described above, the objective lens and the roof prism serve as a waist finder, and by constructing the roof prism as the optical path of the eye level finder, an eye level / waist level combined finder can be achieved. You can also see a bright upright image at both eye level and waist level. Also, by using a condenser lens, it is possible to make a finder with a long eye point at the waist level.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic embodiment of the present invention (a),
(B) and (c) are a perspective view, a cross-sectional view, and a view seen from the eye level eyepoint side, respectively. FIG. 2 shows the objective and exit surfaces of the eye level portion of the roof prism as concave and convex surfaces, respectively. FIG. 3 is a cross-sectional view of an embodiment in which a lens is integrated with a roof prism, FIGS.
The figures are cross-sectional views of Numerical Example 1 and Numerical Example 2, respectively. Fig. 5 is a perspective view showing a conventional eye level / waist level combined finder 6 is an objective lens 7 is a roof prism 8 is a condenser lens

Claims (4)

[Claims] 1. A roof surface for guiding light incident on a waist level objective lens twice to guide it to a waist level eyepiece lens, and an eye level eyepiece lens for advancing light incident on an eye level objective lens. An eye-level / waist-level combined finder comprising a prism having a light guide portion for guiding to. 2. The eye level / waist level combined finder according to claim 1, wherein the waist level objective lens and the prism are integrally formed. 3. The eye level / waist level combined finder according to claim 1, wherein the waist level eyepiece lens is a condenser lens. 4. The eye level / waist level combined finder according to claim 3, wherein the condenser lens and the prism are integrally formed.