JPH02184831A - Finder device for camera - Google Patents

Abstract

PURPOSE:To easily obtain high visual field rate by controlling the installation position of a focusing screen by means of a part of a visual field mask and observing a finder image formed on the focusing screen. CONSTITUTION:The device possesses an opening part 7a which controls the finder visual field of the visual field mask 7 and a bending parts 7b which control the installation position of the focusing screen G1, and the device is sandwiched between a projecting part 3a of a holder 3 and a condenser lens G2. The bending parts 7b are provided for the focusing screen G1 at several points around four sides, and when the focusing screen G1 is installed, the flat position is relatively controlled. Therefore, the phenomenon which causes the deviation of the finder visual field controlled by the finder eye position is prevented. Thus, the visual field rate easily reaches 100%.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a finder device for a camera, and in particular to regulating the mounting position of a focusing screen where a finder image is formed through a part of a field mask forming a viewfinder field of view. This invention relates to a high-quality camera finder device suitable for the finder optical system of an eye reflex camera. be.

(Prior Art) Conventionally, as a finder device for a single-lens reflex camera, one having a configuration as shown in FIG. 5, for example, has been widely known.

This figure shows a case in which the focusing screen is configured to be replaceable from the lens mount side (not shown).

In the figure, reference numeral 1 denotes a case of a focusing screen G1, which is rotatably supported around a shaft 2 supported by a holder 3.

Further, it is held in the holder 3 in the state shown in the figure by an engaging means (not shown).

When replacing the focusing screen G1, the engaging means (not shown) is removed and the case 1 is rotated and lowered.

The holder 3 houses and holds a condenser lens G2, a spacer 4, a mask 6 for regulating the viewfinder field of view, and a pentaprism G3, as shown in the figure, and furthermore, a display prism G5 is fixed to a part of the holder 3. There is.

The mask 6 has an opening 6 that regulates the viewfinder field of view.
a and an opening 6b that restricts the display range when information is displayed within the finder.

Reference numeral 5 denotes an information display device, which is composed of an LED, an LCD, and the like. G4 is an eyepiece lens held in the holder 3 or the camera body (not shown). Reference numeral 9 denotes a focusing surface of the focusing screamo, which is composed of a diffusing surface, and a finder image is formed on the focusing surface.

As shown in Figure 5, the basic configuration of the finder device of a conventional single-lens reflex camera is roughly as shown in the same figure, although there are some differences in the presence or absence of a condenser lens, display method, and whether or not the focusing screen can be replaced. It is configured.

The finder device shown in the figure has the following problems.

That is, in FIG. 5, the position of the mask 6 that regulates the viewfinder field of view and the position of the focus plane 9 (a plane optically equivalent to the film exposure plane) are separated by a certain distance (denoted as d). For this reason, the viewfinder field of view, which is regulated by the position of the eye looking into the finder, shifts.

FIG. 3 is a schematic diagram of an optical system conceptually showing the phenomenon at this time.

In the figure, P is a reference position (nominal position) when observing the finder, and is a so-called eye point. 6 is a mask,
Reference numeral 9 denotes a focusing surface of a focusing screen, which is arranged at a position optically substantially equivalent to the film exposure surface.

If, for example, the nominal position P is swung to the position P' and observed, the viewfinder field of view will be shifted by Δ due to the influence of the distance d between the mask 6 and the focus plane 9. The magnitude of the deviation amount Δ depends on the value of the distance 1i1d.

This shift amount Δ of the finder field of view occurs in optical principle, and since it can be corrected by the field of view ratio when observing the finder field of view, it does not usually pose a problem in photographing.

Note that the coverage ratio here is the ratio of the size of the viewfinder field of view when observing the finder image to the actual screen (the area that is actually exposed on the film), and generally the coverage ratio is 100.
% or less.

That is, the viewfinder field of view is usually set to be slightly smaller than the real screen, and the field of view is set so that objects beyond the range of the real screen cannot be seen from the finder system.

FIG. 4 is a schematic diagram showing the relationship at this time.

The right side of the figure shows the relationship between the viewfinder field of view (the nominal position and the position when the eye is swung in a certain direction) and the actual screen. In the figure, the two-dot chain line is the actual screen photographed on the film surface, the solid line is the nominal position of the finder field of view, and the broken line is the area of the finder field of view observed when the eye is swung in a certain direction, for example.

As is clear from the figure, the smaller the field of view ratio is, the more the field of view shifts (
Δ) can be tolerated.

However, in relatively high-end eye reflex cameras, the field of view ratio is set to a large value, and in this case, the shift in the viewfinder field of view cannot be ignored when photographing.

In particular, in order to achieve a finder optical system with a field of view of approximately 100%, it is necessary to almost eliminate the amount of deviation (Δ) in the viewfinder's field of view.

Therefore, in the finder device having the structure shown in FIG. 5, it is very difficult to achieve a field of view of 100%. Further, the above-mentioned problems have an adverse effect not only on the field of view but also on the following points.

For example, a mark indicating the side light range is generally formed on the focusing screen 01, and the AF left camera also has a mark indicating its distance measurement range (second
(see figure). This facilitates the WL shape of the photographer.

However, in the finder device shown in FIG. 5, if the mask 6 and the focusing screen G1 are held in a plane direction with respect to the holder 3, for example, relative positional displacement or inclination will occur.

As a result, the mark that should normally be displayed in the center of the viewfinder field of view may appear biased in one direction, or the ranging range mark shown in Figure 2 may appear tilted, which is undesirable for photography. .

Moreover, this phenomenon is further aggravated by the field of view deviation, and becomes a cause of a significant deterioration in the quality of the finder optical system. Furthermore, this tendency is undesirable in cameras capable of wide-range AF (autofocus), such as multi-point distance measurement or wide-field distance measurement, because the distance measurement range mark naturally becomes large.

(Problems to be Solved by the Invention) When observing a finder image formed on the surface of the focusing screen, the present invention has a method in which the mounting position of the focusing screen is regulated by a part of the field mask that forms the viewfinder field of view. By configuring 10
A high-quality camera that can easily achieve a high field of view close to 0%, and can also be configured so that the information display of the photometry range mark and distance measurement range mark is placed right in the viewfinder's field of view to avoid bias or tilt. The purpose is to provide a finder device for cameras.

(Means for Solving the Problem) The mounting position of the focusing screen is regulated through a part of the field mask that forms the viewfinder field, and the finder image formed on the focusing screen is observed.

In particular, the present invention is characterized in that the focusing surface of the focusing screen comes into contact with the surface of the field mask.

(Embodiment) FIG. 1 is a schematic diagram of a finder device of a camera according to an embodiment of the present invention, and FIG. 1(B) is an enlarged explanatory diagram of section A shown in FIG. 1(A). In FIGS. 5A and 5B, the same elements as those shown in FIG. 5 are given the same reference numerals.

Reference numeral 7 denotes a field mask, which has an opening 7a that regulates the viewfinder field of view and a bent part 7b that regulates the mounting position of the focusing screen G1, and is held between the holder 3, the convex part 3a, and the condenser lens G2. There is.

The bent portions 7b are provided at several locations around all four sides of the focusing screen G1, and relatively restrict the planar position of the focusing screen G1 when it is mounted.

As shown in FIG. 7B, a notch is formed in the focusing screen G1 corresponding to the bent part 7b on the side of the field mask 7, and a part of the focusing screen G1 is formed using the notch. It is configured to fit into the bent portion 7b.

The surface of the focusing screen G1 on the field mask 7 side is a diffused focusing surface 9 on which a finder image is formed, and the focusing surface 9 is brought into contact with the field mask 7 due to the elasticity of the spring member of the case 1. and regulates the height position of the focusing screen G1.

As a result, the distance (d) between the mask 6 and the focus surface 9 shown in FIG. 5 is eliminated, and the shift in the viewfinder field caused by this distance is eliminated.

8 is a display mask, which is arranged between the pentaprism G3 and the spacer 4. The display mask 8 has an opening 8a that secondarily regulates a wider viewing range than the viewfinder viewing range formed by the opening 7a that regulates the finder field of view,
Furthermore, it has an opening 8b that restricts the information display range.

In addition, the display mask 8 regulates the information display range and prevents reflected light generated on the inner peripheral surface of the spacer 4 and the display prism G5.
This is to prevent reflected light generated at the edges of the eyepiece G4 and harmful light flux (ghost light flux) generated between the field mask 7 and the display mask 8 from reaching the eyepiece G4.

In this embodiment, the mounting position of the focusing screen G1 is regulated as described above through a part of the field mask 7 that forms the viewfinder field, so that the viewfinder field of view is regulated by the position of the eye looking into the finder, which was conventionally regulated. This prevents the phenomenon of shifting.

This eliminates any shift in the viewfinder field of view, making it possible to easily bring the field of view close to 100%, making it possible to always observe the finder image formed on the focusing screen G1 well through the eyepiece G4.

FIG. 2 is an explanatory diagram of the finder field of view when a photometry range mark and a distance measurement range mark are formed on the focusing screen G1 surface shown in FIG. 1(A).

In this figure, the same elements as those shown in FIG. 1(A) are given the same reference numerals.

As shown in the figure, by regulating the mounting position of the focusing screen G1 by the field mask 7 as described above, it is possible to effectively prevent deviations and inclinations of the photometry range mark and the distance measurement range mark.

This makes it easy to provide a good viewfinder field of view that allows the photographer to accurately perform distance measurement, photometry, etc. and take pictures.

In this embodiment, the shape of the bent portion 7b of the field mask 7 is such that a part of the focusing screen G1 is fitted into it.
It may be shaped like a dovetail as long as it has a shape that allows positioning.

(Effects of the Invention) According to the present invention, by regulating the mounting position of the focusing screen by a part of the field mask that regulates the viewfinder field of view, the relative positional deviation in the plane direction of both the focusing screen and the field mask is reduced. It is possible to achieve a camera finder device that can minimize the deviation and tilt of the photometry range mark and the distance measurement range mark that result from this.

Furthermore, according to the present invention, since the heightwise position of the focusing screen is also regulated by the field mask, the field of view deviation (Δ) caused by the distance (d) between the focusing surface of the focusing screen and the mask does not occur at all. As a result, it is possible to achieve a high-quality camera finder device which is particularly suitable for a finder optical system of an eye reflex camera and the like, in which the field of view can easily approach 100%.

[Brief explanation of the drawing]

FIG. 1(A) is a schematic diagram of a finder device of a camera according to an embodiment of the present invention, and FIG.
Figure 2 is an explanatory diagram of the viewfinder field of view showing how the photometry range mark and distance measurement range mark are formed on the focusing screen shown in Figure 1, and Figure 3 is an illustration of the viewfinder field of view. A schematic diagram of the optical system showing the phenomenon that the viewfinder field of view shifts depending on the position. Figure 4 is an explanatory diagram showing the relationship between the viewfinder field of view (nominal position and when shaking the eye) and the actual screen. Figure 5 is a conventional single-lens camera. FIG. 2 is a schematic diagram of a finder device of a reflex camera. In the figure, G1 is a focusing screen, G2 is a condenser lens, G3 is a pentaprism, G4 is an eyepiece, G5 is a display prism, 1 is a focusing screen case, 2 is a shaft, 3 is a holder, 4 is a spacer, and 5 is information A display device, 6 is a mask, 6a and 7a are openings each regulating the viewfinder field of view, 6b and 8b are openings each regulating the information display range in the finder, 7
8 is a field mask, 8 is a display mask, 8a is an aperture that two-dimensionally regulates the viewfinder field of view, and 9 is a focusing surface.

Claims (2)

[Claims] (1) Regulating the mounting position of the focusing screen through a part of the field mask that forms the viewfinder field,
A finder device for a camera, characterized in that a finder image formed on the focusing screen is observed. (2) The finder device for a camera according to claim 1, wherein the focusing surface of the focusing screen is configured to come into contact with the surface of the field mask.