JP2004226725A - Eyepiece and single lens reflex camera equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an eyepiece which can be used for a camera having the size of both surfaces of the extent of half size of a silver salt 35mm film, sets a distance between the surface to be observed and the incident surface of the first lens component of the eyepiece to be the extent of 1.4f when the focal distance is (f), has a high finder magnification, has a high eyepoint and is good in appearance, and to provide a single lens reflex camera equipped with the eyepiece. <P>SOLUTION: The eyepiece comprises a positive first lens component 8a, a positive second lens component 8b and a negative third lens component 8c in the order from a projector side and satisfies the following relation: 2.5<fb/Y<4.0, -1.0<f3/f< -0.2, 0.4<f1/f<0.95. Therein, fb is an air-equivalent length from the surface to be observed up to the incident surface of the first lens component, Y is a screen diagonal length (mm) on the surface to be observed, f3 is the focal distance of the third lens component, f1 is the focal distance of the first lens component and (f) is the focal distance of total system of the eyepiece in diopter of -0.5(m<SP>-1</SP>). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００４０】
第２実施例
図５は本発明による接眼レンズを備えた一眼レフカメラの第２実施例にかかる光学構成を示す光軸に沿う断面図であり、視度が−０．５ｍ^−１のときの状態を示している。なお、図５における平行平板状部材は説明の便宜上ペンタダハプリズムを転開して示したものである。図６は第２実施例における球面収差、像面湾曲、歪曲収差、倍率色収差を示す図であり、（ａ）は視度が＋１ｍ^−１のとき、（ｂ）は視度が−０．５ｍ^−１のとき、（ｃ）は視度が−３ｍ^−１のときの状態を示している。なお、図６の球面収差と像面湾曲における横軸は視度（ｍ^−１）であり、倍率色収差における横軸は角度（分）である。
第２実施例の接眼レンズを備えた一眼レフカメラは、ペンタダハプリズム７と、接眼レンズ８を備えている。
接眼レンズ８は、被写体側より順に、両凸正レンズからなる正の屈折力を持つ第１レンズ成分８ａと、被写体側に凸面を向けた１枚の正メニスカスレンズからなる正の屈折力を持つ第２レンズ成分８ｂと、両凸正レンズと両凹負レンズとの接合レンズからなり全体で負の屈折力を持つ第３レンズ成分８ｃ’とで構成されている。また、視度調整は第２レンズ成分８ｂを移動して行うようになっている。
【００４１】
次に、第２実施例の接眼レンズを構成する光学部材の数値データを示す。
数値データ２

【００４２】
第３実施例
図７は本発明による接眼レンズを備えた一眼レフカメラの第３実施例にかかる光学構成を示す光軸に沿う断面図であり、視度が−０．５ｍ^−１のときの状態を示している。なお、図７における平行平板状部材は説明の便宜上ペンタダハプリズムを転開して示したものである。図８は第３実施例における球面収差、像面湾曲、歪曲収差、倍率色収差を示す図であり、（ａ）は視度が＋１ｍ^−１のとき、（ｂ）は視度が−０．５ｍ^−１のとき、（ｃ）は視度が−３ｍ^−１のときの状態を示している。なお、図８の球面収差と像面湾曲における横軸は視度（ｍ^−１）であり、倍率色収差における横軸は角度（分）である。
第３実施例の接眼レンズを備えた一眼レフカメラは、ペンタダハプリズム７と、接眼レンズ８を備えている。
接眼レンズ８は、被写体側より順に、両凸正レンズからなる正の屈折力を持つ第１レンズ成分８ａと、被写体側に凸面を向けた１枚の正メニスカスレンズからなる正の屈折力を持つ第２レンズ成分８ｂと、両凸正レンズと両凹負レンズとの接合レンズからなり全体で負の屈折力を持つ第３レンズ成分８ｃ’とで構成されている。また、視度調整は第２レンズ成分８ｂを移動して行うようになっている。
【００４３】
次に、第３実施例の接眼レンズを構成する光学部材の数値データを示す。
数値データ３

【００４４】
第４実施例
図９は本発明による接眼レンズを備えた一眼レフカメラの第４実施例にかかる光学構成を示す光軸に沿う断面図であり、視度が−０．５ｍ^−１のときの状態を示している。なお、図９における平行平板状部材は説明の便宜上ペンタダハプリズムを転開して示したものである。図１０は第４実施例における球面収差、像面湾曲、歪曲収差、倍率色収差を示す図であり、（ａ）は視度が＋１ｍ^−１のとき、（ｂ）は視度が−０．５ｍ^−１のとき、（ｃ）は視度が−３ｍ^−１のときの状態を示している。なお、図１０の球面収差と像面湾曲における横軸は視度（ｍ^−１）であり、倍率色収差における横軸は角度（分）である。
第４実施例の接眼レンズを備えた一眼レフカメラは、ペンタダハプリズム７と、接眼レンズ８を備えている。
接眼レンズ８は、被写体側より順に、被写体側に凸面を向けた負メニスカスレンズと両凸正レンズとを接合してなり全体で正の屈折力を持つ第１レンズ成分８ａ’と、被写体側に凸面を向けた１枚の正メニスカスレンズからなる正の屈折力を持つ第２レンズ成分８ｂと、被写体側に凸面を向けた負メニスカスレンズからなる負の屈折力を持つ第３レンズ成分８ｃ”とで構成されている。また、視度調整は第２レンズ成分８ｂを移動して行うようになっている。
【００４５】
次に、第４実施例の接眼レンズを構成する光学部材の数値データを示す。
数値データ４

【００４６】
第５実施例
図１１は本発明による接眼レンズを備えた一眼レフカメラの第５実施例にかかる光学構成を示す光軸に沿う断面図であり、視度が−０．５ｍ^−１のときの状態を示している。なお、図１１における平行平板状部材は説明の便宜上ペンタダハプリズムを転開して示したものである。図１２は第５実施例における球面収差、像面湾曲、歪曲収差、倍率色収差を示す図であり、（ａ）は視度が＋１ｍ^−１のとき、（ｂ）は視度が−０．５ｍ^−１のとき、（ｃ）は視度が−３ｍ^−１のときの状態を示している。なお、図１２の球面収差と像面湾曲における横軸は視度（ｍ^−１）であり、倍率色収差における横軸は角度（分）である。
第５実施例の接眼レンズを備えた一眼レフカメラは、ペンタダハプリズム７と、接眼レンズ８を備えている。
接眼レンズ８は、被写体側より順に、両凸正レンズからなる正の屈折力を持つ第１レンズ成分８ａと、被写体側に凸面を向けた１枚の正メニスカスレンズからなる正の屈折力を持つ第２レンズ成分８ｂと、両凸正レンズと両凹負レンズとの接合レンズからなり全体で負の屈折力を持つ第３レンズ成分８ｃ’とで構成されている。また、視度調整は第２レンズ成分８ｂを移動して行うようになっている。
【００４７】
次に、第５実施例の接眼レンズを構成する光学部材の数値データを示す。
数値データ５

【００４８】
次に、各実施例における本発明の条件式の数値を次の表１に示す。
表１

【００４９】
また、各実施例における要素値を次の表２に示す。
表２

【００５０】
以上説明したように、本発明の接眼レンズ及びそれを備えた一眼レフカメラは、特許請求の範囲に記載された特徴の他に、次に示すような特徴も備えている。
【００５１】
（１）被写体側より順に、正の屈折力を持つ第１レンズ成分と、被写体側に凸面を向けた１枚のメニスカスレンズよりなる正の屈折力を持つ第２レンズ成分と、瞳側の面の屈折力が被写体側の面の屈折力よりも強い、全体で負の屈折力を持つ第３レンズ成分を有し、次の条件式を満足することを特徴とする接眼レンズ。
２．５ ＜ ｆｂ／Ｙ ＜ ４．０
０．４ ＜ ｆ１／ｆ ＜ ０．９５
ただし、ｆｂは被観察面から第１レンズ成分の入射面までの空気換算長、Ｙは被観察面における画面対角長（ｍｍ）、ｆ１は第１レンズ成分の焦点距離、ｆは視度−０．５（ｍ^−１）における接眼レンズ全系の焦点距離である。
【００５２】
（２）被写体側より順に、正の屈折力を持つ第１レンズ成分と、被写体側に凸面を向けた１枚のメニスカスレンズよりなる正の屈折力を持つ第２レンズ成分と、瞳側の面の屈折力が被写体側の面の屈折力よりも強い、全体で屈折力を持つ第３レンズ成分とを有し、次の条件式を満足することを特徴とする接眼レンズ。
−１．０ ＜ ｆ３／ｆ ＜ −０．２
０．４ ＜ ｆ１／ｆ ＜ ０．９５
ただし、ｆ３は第３レンズ成分の焦点距離、ｆ１は第１レンズ成分の焦点距離、ｆは視度−０．５（ｍ^−１）における接眼レンズ全系の焦点距離である。
【００５３】
（３）被写体側より順に、正の屈折力を持つ第１レンズ成分と、被写体側に凸面を向けた１枚のメニスカスレンズよりなる正の屈折力を持つ第２レンズ成分と、瞳側の面の屈折力が被写体側の面の屈折力よりも強い、全体で負の屈折力を持つ第３レンズ成分とを有し、次の条件式を満足することを特徴とする接眼レンズ。
０．４ ＜ ｆ１／ｆ ＜ ０．９５
ただし、ｆ１は第１レンズ成分の焦点距離、ｆは視度−０．５（ｍ^−１）における接眼レンズ全系の焦点距離である。
【００５４】
（４）次の条件式を満足することを特徴とする請求項１、２、上記（１）〜（３）のいずれかに記載の接眼レンズ。
１６．０ ＜ Ｙ ＜ ２８．０
ただし、Ｙは被観察面における画面対角長（ｍｍ）である。
【００５５】
（５）次の条件式を満足することを特徴とする請求項１、２、上記（１）〜（４）のいずれかに記載の接眼レンズ。
０．５ ＜ ｆ２／ｆ ＜ １．２
ただし、ｆ２は第２レンズ成分の焦点距離、ｆは視度−０．５（ｍ^−１）における接眼レンズ全系の焦点距離である。
【００５６】
（６）次の条件式を満足することを特徴とする請求項１、２、上記（１）〜（５）のいずれかに記載の接眼レンズ。
−１．３ ＜ ｆ１２／ｆ３ ＜ −０．９
ただし、ｆ１２は第１レンズ成分と第２レンズ成分との合成焦点距離、ｆ３は第３レンズ成分の焦点距離である。
【００５７】
（７）前記第１レンズ成分にアッベ数が８０以上である正レンズを用いたことを特徴とする請求項１、２、上記（１）〜（６）のいずれかに記載の接眼レンズ。
【００５８】
（８）前記第２レンズ成分を光軸方向に移動させることにより視度調整を行うようにしたことを特徴とする請求項１、２、上記（１）〜（５）のいずれかに記載の接眼レンズ。
【００５９】
（９）第レンズ成分又は第３レンズ成分が接合レンズで構成されていることを特徴とする請求項１、２、上記（１）〜（８）のいずれかに記載の接眼レンズ。
【００６０】
（１０）４枚のレンズで構成されていることを特徴とする請求項１、２、上記（１）〜（９）のいずれかに記載の接眼レンズ。
【００６１】
（１１）被写体の像が投影されるスクリーン面と、前記スクリーン面上の像を正立化させるための複数の反射面と、前記像を観察するための正の屈折力を持つ接眼レンズとを含む一眼レフカメラにおいて、上記（１）〜（１０）のいずれかに記載の接眼レンズを備えたことを特徴とする一眼レフカメラ。
【００６２】
【発明の効果】
本発明の接眼レンズ及びそれを備えた一眼レフカメラによれば、画面サイズが銀塩３５ｍｍフィルムの半分程度で、焦点距離をｆとしたときに被観察面から第１レンズ成分の入射面まで距離が１．４ｆ程度と長く、かつ、ファインダ倍率が高倍率でハイアイポイントな見えの良い接眼レンズ及びそれを備えた一眼レフカメラを得ることができる。
【図面の簡単な説明】
【図１】本発明の接眼レンズを備えた一眼レフカメラの一実施形態を示す各実施例に共通の概略構成図である。
【図２】本発明の各条件式における要素を説明するための図であり、砂ずり面等で構成されるスクリーン面を示したものである。
【図３】本発明による接眼レンズを備えた一眼レフカメラの第１実施例にかかる光学構成を示す光軸に沿う断面図であり、視度が−０．５ｍ^−１のときの状態を示している。
【図４】第１実施例における球面収差、像面湾曲、歪曲収差、倍率色収差を示す図であり、（ａ）は視度が＋１ｍ^−１のとき、（ｂ）は視度が−０．５ｍ^−１のとき、（ｃ）は視度が−３ｍ^−１のときの状態を示している。
【図５】本発明による接眼レンズを備えた一眼レフカメラの第２実施例にかかる光学構成を示す光軸に沿う断面図であり、視度が−０．５ｍ^−１のときの状態を示している。
【図６】第２実施例における球面収差、像面湾曲、歪曲収差、倍率色収差を示す図であり、（ａ）は視度が＋１ｍ^−１のとき、（ｂ）は視度が−０．５ｍ^−１のとき、（ｃ）は視度が−３ｍ^−１のときの状態を示している。
【図７】本発明による接眼レンズを備えた一眼レフカメラの第３実施例にかかる光学構成を示す光軸に沿う断面図であり、視度が−０．５ｍ^−１のときの状態を示している。
【図８】第３実施例における球面収差、像面湾曲、歪曲収差、倍率色収差を示す図であり、（ａ）は視度が＋１ｍ^−１のとき、（ｂ）は視度が−０．５ｍ^−１のとき、（ｃ）は視度が−３ｍ^−１のときの状態を示している。
【図９】本発明による接眼レンズを備えた一眼レフカメラの第４実施例にかかる光学構成を示す光軸に沿う断面図であり、視度が−０．５ｍ^−１のときの状態を示している。
【図１０】第４実施例における球面収差、像面湾曲、歪曲収差、倍率色収差を示す図であり、（ａ）は視度が＋１ｍ^−１のとき、（ｂ）は視度が−０．５ｍ^−１のとき、（ｃ）は視度が−３ｍ^−１のときの状態を示している。
【図１１】本発明による接眼レンズを備えた一眼レフカメラの第５実施例にかかる光学構成を示す光軸に沿う断面図であり、視度が−０．５ｍ^−１のときの状態を示している。
【図１２】第５実施例における球面収差、像面湾曲、歪曲収差、倍率色収差を示す図であり、（ａ）は視度が＋１ｍ^−１のとき、（ｂ）は視度が−０．５ｍ^−１のとき、（ｃ）は視度が−３ｍ^−１のときの状態を示している。
【符号の説明】
１ 一眼レフカメラ
２ 撮影レンズ
３ 光軸
４ ＣＣＤ
５ クイックリターンミラー
６ スクリーン面
７ ペンタダハプリズム
８ 接眼レンズ
８ａ，８ａ’ 正の屈折力を有する第１レンズ成分
８ｂ 正の屈折力を有する第２レンズ成分
８ｃ，８ｃ’，８ｃ” 負の屈折力を有する第３レンズ成分
９ 平行平面板（カバーガラス）
１０ 観察者の瞳（射出瞳）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an eyepiece of a viewfinder for a single-lens reflex camera, and more particularly to an eyepiece suitable for a camera having a screen size about half that of a silver halide 35 mm film, and a single-lens reflex camera provided with the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, digital cameras have been attracting attention as next-generation cameras that can replace silver halide 35 mm film cameras.
The size of a CCD or the like used as an image pickup device of this digital camera is about one-tenth to one-tenth in diagonal length as compared with a silver halide 35 mm film.
If the eyepiece of the conventional camera is used as it is for such a camera having a small screen size, the observation image becomes small, and thus the fatigue of the photographer during use increases.
For this reason, when a single-lens reflex system is introduced in this type of camera, it is necessary to increase the finder magnification in order to increase the image appearance.
[0003]
In order to increase the magnification of the viewfinder, the focal length of the infinity lens must be shortened. However, generally, when the focal length of the eyepiece is shortened, the distance from the observation surface to the entrance surface of the first lens component of the eyepiece tends to be short.
On the other hand, in order to secure a space for disposing various optical members such as a penta roof prism, the distance from the surface to be observed to the first lens component of the eyepiece must be sufficiently long.
[0004]
In order to make the viewfinder easy to see, it is necessary to ensure a long distance from the eyepiece to the pupil position of the observer, that is, a so-called eye relief, and to minimize kicking. It is necessary to make the distance from to the first lens component of the eyepiece sufficiently long.
This is because, generally, in order to secure a long eye relief (a high eye point), it is necessary to enlarge the aperture of the eyepiece and to enlarge the effective aperture on the exit surface of the penta roof prism. At this time, the size of the pentadahub rhythm itself increases with the enlargement of the effective aperture on the exit surface, and the optical path length developed in the prism increases.
[0005]
From the above, at the same time that the finder magnification is high, it is possible to secure a space where various optical members such as prisms can be arranged, and to realize an eyepiece with a high eye point, it is necessary to use a short focal length It is essential to satisfy the conflicting requirements of ensuring a sufficiently long distance from the surface to be observed to the entrance surface of the first lens component of the eyepiece.
[0006]
Conventionally, as eyepieces having a longer distance from the observation surface to the entrance surface of the first lens component of the eyepiece than the focal length, for example, those described in Patent Documents 1 and 2 are known.
[0007]
[Patent Document 1]
Japanese Patent Publication No. 07-1070581
[Patent Document 2]
Japanese Patent No. 2726261
[0008]
[Problems to be solved by the invention]
However, the limitable lenses described in Patent Documents 1 and 2 have a distance from the observed surface to the entrance surface of the first lens component of the eyepiece lens of about 1.1 f when the focal length of the entire eyepiece lens system is f. However, it could not be said that a sufficient length was secured.
[0009]
The present invention has been made in view of the above problems, and can be used for a camera having a screen size of about half of a silver halide 35 mm film, and the first lens of the eyepiece from the observation surface when the focal length is f. It is an object of the present invention to provide an eyepiece having a high finder magnification, a high eye point, and a high eye point, and a single-lens reflex camera equipped with the same, which can provide a distance of about 1.4f to the incident surface of the component. .
[0010]
[Means for Solving the Problems]
To achieve the above object, the eyepiece according to the first aspect of the present invention includes, in order from the object side, a first lens component having a positive refractive power, a second lens component having a positive refractive power, and a negative refractive power. And a third lens component satisfying the following conditional expressions (1), (2), and (3).
2.5 <fb / Y <4.0 (1)
−1.0 <f3 / f <−0.2 (2)
0.4 <f1 / f <0.95 (3)
Here, fb is the air-equivalent length from the observation surface to the entrance surface of the first lens component, Y is the screen diagonal length (mm) on the observation surface, f3 is the focal length of the third lens component, and f1 is the first lens. The focal length of the component, f, is diopter -0.5 (m^-1) Is the focal length of the whole eyepiece system.
[0011]
The eyepiece according to the second aspect of the present invention has a first lens component having a positive refractive power and a positive meniscus lens having a convex surface facing the subject in order from the subject side. It has two lens components and a third lens component having a negative refractive power as a whole, in which the refractive power of the surface on the pupil side is stronger than the refractive power of the surface on the subject side, and satisfies the following conditional expression: And
2.5 <fb / Y <4.0
−1.0 <f3 / f <−0.2
0.4 <f1 / f <0.95
Here, fb is the air-equivalent length from the observation surface to the entrance surface of the first lens component, Y is the screen diagonal length (mm) on the observation surface, f3 is the focal length of the third lens component, and f1 is the first lens. The focal length of the component, f, is diopter -0.5 (m^-1) Is the focal length of the whole eyepiece system.
[0012]
The single-lens reflex camera including the eyepiece according to the third aspect of the present invention includes a screen surface on which an image of a subject is projected, a plurality of reflecting surfaces for erecting an image on the screen surface, and A single-lens reflex camera including an eyepiece having a positive refractive power for observing the eyepiece, wherein the eyepiece of the first or second invention is provided.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Prior to the description of the embodiments, the operation of the present invention will be described.
Like the eyepiece of the present invention, a first lens component having a positive refractive power, a second lens component having a positive refractive power, and a third lens component having a negative refractive power are provided in order from the subject side. With this arrangement, the principal point position of the eyepiece can be shifted to the subject side by the arrangement having the refractive power in the order of positive and negative, and the position from the observation surface to the entrance surface of the first lens component of the eyepiece can be shifted. A sufficient distance can be secured.
[0014]
Further, when the second lens component is constituted by one meniscus lens having a convex surface facing the subject side as in the eyepiece of the second aspect of the present invention, the principal point position of the eyepiece can be further shifted to the subject side. It is more advantageous to secure a long distance from the observation surface to the entrance surface of the first lens component of the eyepiece.
[0015]
In the eyepiece of the present invention, the height of the off-axis principal ray passing through the third lens component is higher on the object side than on the pupil side.
For this reason, like the eyepiece of the second aspect, the third lens component is a lens component having a negative refractive power as a whole, in which the refractive power of the pupil-side surface is stronger than the refractive power of the subject-side surface. In this case, the amount of aberrations can be reduced as a whole.
[0016]
Next, the conditional expression will be described.
In the viewfinder of a single-lens reflex camera having an eyepiece, an erecting erect image optical member such as a pentadaha rhythm or a penta-Dach mirror is arranged in a space from a surface to be observed to an incident surface of a first lens component of the eyepiece. Is done. Therefore, a space is required for these members to be configured without any problem.
Therefore, in the eyepiece of the present invention, the distance from the surface to be observed to the entrance surface of the first lens component of the eyepiece preferably satisfies the following conditional expression (1).
2.5 <fb / Y <4.0 (1)
Here, fb is the air conversion length from the observation surface to the incident surface of the first lens component, and Y is the screen diagonal length (mm) on the observation surface.
If the lower limit of conditional expression (1) is not reached, the space from the surface to be observed to the entrance surface of the first lens component of the eyepiece will be insufficient, and an erect image system cannot be formed. On the other hand, when the value exceeds the upper limit of the conditional expression (1), sufficient aberration correction cannot be performed.
[0017]
It is more preferable to set the lower limit of conditional expression (1) to 2.8 or 3.0, and it is more preferable to set the upper limit of conditional expression (1) to 3.75 or 3.5.
For example, it is more desirable to satisfy the following conditional expressions (1-1) and (1-2).
2.8 <fb / Y <4.0 (1-1)
3.0 <fb / Y <3.75 (1-2)
[0018]
As described above, the eyepiece of the present invention is arranged such that the refractive power of each lens component is positive, positive, and negative, and the negative refractive power of the third lens component is increased to position the front principal point at the eyepiece. By shifting to the subject side, a sufficient distance from the observation surface to the incident surface of the first lens component of the eyepiece is secured without increasing the focal length.
At this time, it is preferable to satisfy the following conditional expression (2).
−1.0 <f3 / f <−0.2 (2)
Here, f3 is the focal length of the third lens component, and f is diopter -0.5 (m^-1) Is the focal length of the whole eyepiece system.
When the lower limit of conditional expression (2) is exceeded and the negative refractive power of the third lens component is weakened, the effect of shifting the front principal point position to the object side of the eyepiece is weakened, and the effect of shifting the position of the eyepiece from the observation surface to the eyepiece of the eyepiece is reduced. It becomes impossible to secure a sufficient distance to the entrance surface of one lens component.
On the other hand, when the value exceeds the upper limit of conditional expression (2) and the negative refractive power of the third lens component becomes strong, it becomes impossible to perform sufficient aberration correction.
[0019]
It is more preferable to set the lower limit of conditional expression (2) to -0.8 or -0.53, and it is more preferable to set the upper limit to -0.25 or -0.3.
For example, it is more desirable to satisfy the following conditional expressions (2-1) and (2-2).
−0.8 <f3 / f <−0.2 (2-1)
−0.53 <f3 / f <−0.25 (2-2)
[0020]
The eyepiece of the present invention preferably satisfies the following conditional expression (3) in order to give the first lens component an appropriate refractive power.
0.4 <f1 / f <0.95 (3)
Here, f1 is the focal length of the first lens component, and f is diopter -0.5 (m^-1) Is the focal length of the whole eyepiece system.
If the lower limit of conditional expression (3) is exceeded and the positive refractive power of the first lens component becomes strong, it will be difficult to sufficiently perform aberration correction.
On the other hand, if the refractive power of the first lens component is weaker than the upper limit value of the conditional expression (3), the ray height on the object side becomes higher than the first lens component. Is kicked by a prism or the like arranged in the lens, and the eye relief cannot be lengthened.
[0021]
It is more preferable to set the lower limit of conditional expression (3) to 0.45 or 0.5, and it is more preferable to set the upper limit to 0.87 or 0.85.
For example, it is more desirable to satisfy the following conditional expressions (3-1) or (3-2).
0.45 <f1 / f <0.87 (3-1)
0.5 <f1 / f <0.85 (3-2)
[0022]
Since the eyepiece of the present invention is configured to shorten the focal length and at the same time increase the negative refractive power to shift the front principal point to the subject side of the eyepiece, it is inevitably positive and negative. Each lens component having a refractive power has a high power. For this reason, it becomes difficult to correct axial chromatic aberration by balancing the refractive power of a lens component having a positive refractive power and a lens component having a negative refractive power.
In order to set the arrangement of the refractive power of each lens component to have an appropriate balance and to more effectively correct the axial chromatic aberration, the first lens component or the third lens component is constituted by a cemented lens, and It is desirable to minimize the occurrence of chromatic aberration in the lens component.
As will be described later, the second lens component is constituted by a positive meniscus lens composed of only one lens in consideration of moving the lens component for diopter adjustment, and the weight burden on the lens driving system is increased. Is desirable.
[0023]
Further, when the high eye point is realized by the arrangement of the refracting power like the eyepiece of the present invention, the height of the off-axis principal ray in the first lens component tends to increase. Then, since the difference in the height of the off-axis principal ray between the positive first lens component and the negative third lens component becomes large, the amount of chromatic aberration of magnification greatly differs between the two lens components, and it is difficult to correct it. And the chromatic aberration of magnification generated by the first lens component remains. In order to minimize the remaining amount of lateral chromatic aberration, it is effective to use a low-dispersion glass material for the first lens component. Specifically, it is preferable to use a glass material having an Abbe number of 80 or more for the first lens component. More preferably, it is desirable to use a glass material having an Abbe number of 80 or more and 100 or less, or 81 or more and 95 or less.
[0024]
The screen size of the single-lens reflex camera used for the eyepiece of the present invention is about half that of a silver halide film.
Therefore, the eyepiece of the present invention preferably satisfies the following conditional expression (4).
16.0 <Y <28.0 (4)
Here, Y is the screen diagonal length (mm) on the observation surface.
If the screen size is smaller than the lower limit of conditional expression (4), the finder magnification must be further increased, which is difficult to realize with the configuration of the present invention, and requires a more complicated optical system.
On the other hand, if the screen size becomes larger than the upper limit value of the conditional expression (4), the size of the whole camera becomes large, which is not preferable.
[0025]
It is more preferable to set the lower limit of conditional expression (4) to 18.0 or 20.0, and it is more preferable to set the upper limit to 27.0 or 26.0.
For example, it is more desirable to satisfy the following conditional expressions (4-1) or (4-2).
18.0 <Y <27.0 (4-1)
20.0 <Y <26.0 (4-2)
[0026]
In addition, it is desirable to move the second lens component alone for diopter adjustment. By doing so, the front and rear of the movable group are sealed with a fixed lens, so that dust can be prevented from entering the viewfinder. Further, since the first lens component can be fixed, a space around the first lens component can be used as a space for disposing other members, for example.
[0027]
Further, as described above, the eyepiece of the present invention comprises, in order from the subject side, a first lens component having a positive refractive power, a second lens component having a positive refractive power, and a third lens having a negative refractive power. With the three lens components, the distance from the surface to be observed to the entrance surface of the first lens component of the eyepiece is increased.
At this time, if the number of lenses constituting the eyepiece is set to four or less, and particularly to four, sufficient performance can be ensured and the cost can be reduced.
[0028]
Further, as described above, the eyepiece of the present invention increases the negative refractive power of the third lens component and shifts the front principal point to the subject side of the eyepiece, thereby increasing the focal length. The distance from the observation surface to the entrance surface of the first lens component of the eyepiece is sufficiently long.
At this time, the first lens component and the second lens component having a positive refractive power bear substantially the same level of refracting power in order to suppress the occurrence of aberration, and the following conditional expression (5): It is desirable to satisfy
0.5 <f2 / f <1.2 (5)
Here, f2 is the focal length of the second lens component, and f is diopter -0.5 (m^-1) Is the focal length of the whole eyepiece system.
When the value goes below the lower limit of conditional expression (5), the refractive power of the second lens component becomes strong, and the Petzval sum deteriorates. In addition, when the diopter is adjusted by moving the second lens component, the aberration changes in each diopter state, and in particular, the fluctuation of spherical aberration and astigmatism increases. For this reason, it becomes difficult to properly correct the aberration over the entire diopter adjustment range.
On the other hand, when the value exceeds the upper limit of conditional expression (5), the refractive power of the second lens component becomes weak, and the height of the off-axis principal ray at the first lens becomes high. For this reason, the off-axis aberration generated in the first lens component increases, and in particular, the chromatic aberration of magnification increases, which makes it difficult to correct. Further, since the height of the light beam is increased, the beam is kicked by a prism or the like, and it becomes impossible to secure a sufficient eye relief.
[0029]
It is more preferable to set the lower limit of conditional expression (5) to 0.55 or 0.6, and it is more preferable to set the upper limit to 1.0 or 1.2.
For example, it is more desirable to satisfy the following conditional expressions (5-1) or (5-2).
0.55 <f2 / f <1.0 (5-1)
0.6 <f2 / f <0.9 (5-2)
[0030]
In order to increase the negative refractive power of the third lens component and shift the front principal point toward the object side of the eyepiece, the eyepiece according to the present invention must satisfy the following conditional expression (6). preferable.
-1.3 <f12 / f3 <-0.9 (6)
Here, f12 is a combined focal length of the first lens component and the second lens component, and f3 is a focal length of the third lens component.
When the value goes below the lower limit of conditional expression (6), the negative refractive power of the third lens component becomes too strong, and it becomes difficult to perform aberration correction.
On the other hand, when the value exceeds the upper limit value of the conditional expression (6), the front principal point cannot be sufficiently shifted to the subject side of the eyepiece, and thus the distance from the observation surface to the entrance surface of the first lens component of the eyepiece. It is difficult to secure a sufficient length.
[0031]
It is more preferable that the lower limit of conditional expression (6) be -1.25 or -1.2, and it is more preferable that the upper limit be -0.95 or -1.0.
For example, it is more desirable to satisfy the following conditional expressions (6-1) or (6-2).
−1.25 <f12 / f3 <−0.95 (6-1)
−1.2 <f12 / f3 <−1.0 (6-2)
[0032]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram common to each example showing one embodiment of a single-lens reflex camera provided with an eyepiece of the present invention.
The single-lens reflex camera 1 of FIG. 1 is configured such that a photographing lens 2 is replaceable with respect to the camera by a mount unit (not shown). In the present invention, a single-lens reflex camera is defined as a single-lens reflex camera, even if the configuration does not include a photographic lens, if the photographic lens is configured to be attachable.
[0033]
In FIG. 1, reference numeral 4 denotes a CCD as an electronic image pickup device, which performs image processing by a processing circuit based on a signal from the CCD and stores image information in a memory. The stored image information can be image-displayed by a personal computer (not shown) or the like, or the information can be recorded and stored in various information storage media.
Reference numeral 5 denotes a quick return mirror disposed on the optical axis 3 of the photographing lens 2 between the photographing lens 2 and the CCD 4, and 6 denotes a finder screen disposed on an optical path reflected by the quick return mirror. The surface side is composed of a sand surface.
Reference numeral 7 denotes a penta roof prism. The penta roof prism 7 includes a plane incident surface 7a, a roof reflecting surface 7b, a plane reflecting surface 7c, and a plane emitting surface 7d in the order of optical paths.
Reference numeral 8 denotes an eyepiece, which is configured in any one of the embodiments described below.
A parallel flat plate 9 as a cover glass is provided on the exit side of the eyepiece 8.
Then, the emitted light flux is guided to the pupil 10 of the observer, and the image to be photographed is observed.
[0034]
Note that the single-lens reflex camera of the present invention may have a configuration in which the taking lens 2 is integrated with the single-lens reflex camera body and is not replaceable with the single-lens reflex camera.
Further, a configuration in which a photographic film is arranged instead of the CCD 4 may be used.
Further, a configuration using a half mirror or an optical path splitting prism instead of the quick return mirror 5 may be used.
Further, the screen surface 6 may be constituted by a surface on which minute prisms are gathered, a hologram surface, or the like, in addition to the sand surface.
Further, the surface facing the screen surface 6 may be constituted by an optical surface having a converging function such as a Fresnel lens surface or a convex surface so as to enhance the light condensing function around the screen.
[0035]
Further, in addition to the penta roof prism 7, a configuration including a roof mirror and a plane mirror, or a configuration having a plurality of reflection surfaces separately for erecting an image may be employed.
When a prism is used in the image erecting system, aberration correction and light collection can be performed by providing an optical refracting power on the entrance surface or the exit surface, or by disposing a field lens near the screen surface 6. It is possible to improve efficiency and the like.
In this case, the focal length f of the entire system is a value obtained by adding the refractive power of this prism. On the other hand, the air conversion length fb may be an air conversion length from the screen surface 6 to the entrance surface of the first lens component 8a of the eyepiece 8.
[0036]
FIG. 2 is a diagram for explaining each element in each conditional expression of the present invention.
FIG. 2 shows a screen surface 6 composed of a sand surface or the like. On the screen surface 6 or in the vicinity thereof, a configuration (for example, black painting, a field frame, or the like) for restricting the field of view is provided. Y is the screen diagonal length of the observable range on the screen surface 6.
[0037]
First embodiment
FIG. 3 is a sectional view along an optical axis showing an optical configuration according to a first embodiment of a single-lens reflex camera provided with an eyepiece according to the present invention.^-1The state at the time of is shown. Note that the parallel plate-like member in FIG. 3 is obtained by rolling a penta roof prism for convenience of explanation. FIG. 4 is a diagram showing spherical aberration, field curvature, distortion, and chromatic aberration of magnification in the first embodiment.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown. The horizontal axis of the spherical aberration and the field curvature of FIG.^-1), And the horizontal axis in the lateral chromatic aberration is the angle (minute).
The single-lens reflex camera having the eyepiece of the first embodiment includes a penta roof prism 7 and an eyepiece 8.
The eyepiece 8 has, in order from the subject side, a first lens component 8a having a positive refractive power composed of a biconvex positive lens and a positive refractive power composed of a single positive meniscus lens having a convex surface facing the subject side. It is composed of a second lens component 8b and a third lens component 8c having a negative refractive power and comprising a biconcave negative lens. The diopter adjustment is performed by moving the second lens component 8b.
[0038]
Next, numerical data of optical members constituting a single-lens reflex camera provided with the eyepiece according to the first embodiment will be shown.
In the numerical data of the first embodiment, r₁, R₂, ... are the radii of curvature of each lens surface or prism surface, d₁, D₂,... Indicate the thickness or air space of each lens or prism, n_d1, N_d2, ... are the refractive indices of each lens or prism at d-line, ν_d1, Ν_d2,... Represent the Abbe number of each lens or prism, and f represents the focal length of the entire system from the screen surface to the eyepiece exit surface.
These symbols are common to the numerical data of the embodiments described later.
[0039]
Numeric data 1

[0040]
Second embodiment
FIG. 5 is a sectional view along an optical axis showing an optical configuration according to a second embodiment of the single-lens reflex camera provided with the eyepiece according to the present invention.^-1The state at the time of is shown. In addition, the parallel plate-shaped member in FIG. 5 is obtained by rolling a penta roof prism for convenience of explanation. FIG. 6 is a diagram showing spherical aberration, field curvature, distortion, and chromatic aberration of magnification in the second embodiment.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown. The horizontal axis of the spherical aberration and the curvature of field in FIG.^-1), And the horizontal axis in the lateral chromatic aberration is the angle (minute).
The single-lens reflex camera provided with the eyepiece of the second embodiment includes a penta roof prism 7 and an eyepiece 8.
The eyepiece 8 has, in order from the subject side, a first lens component 8a having a positive refractive power composed of a biconvex positive lens and a positive refractive power composed of a single positive meniscus lens having a convex surface facing the subject side. It is composed of a second lens component 8b and a third lens component 8c 'composed of a cemented lens of a biconvex positive lens and a biconcave negative lens and having a negative refractive power as a whole. The diopter adjustment is performed by moving the second lens component 8b.
[0041]
Next, numerical data of optical members constituting the eyepiece of the second embodiment will be shown.
Numeric data 2

[0042]
Third embodiment
FIG. 7 is a sectional view along an optical axis showing an optical configuration according to a third embodiment of a single-lens reflex camera provided with an eyepiece according to the present invention, and has a diopter of -0.5 m.^-1The state at the time of is shown. Note that the parallel plate-like member in FIG. 7 is obtained by rolling a penta roof prism for convenience of explanation. FIG. 8 is a diagram showing spherical aberration, curvature of field, distortion, and chromatic aberration of magnification in the third embodiment.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown. The horizontal axis of the spherical aberration and the curvature of field in FIG.^-1), And the horizontal axis in the lateral chromatic aberration is the angle (minute).
The single-lens reflex camera provided with the eyepiece of the third embodiment includes a penta roof prism 7 and an eyepiece 8.
The eyepiece 8 has, in order from the object side, a first lens component 8a having a positive refractive power composed of a biconvex positive lens, and a positive refractive power composed of one positive meniscus lens having a convex surface facing the object side. It is composed of a second lens component 8b and a third lens component 8c 'which is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens and has a negative refractive power as a whole. The diopter adjustment is performed by moving the second lens component 8b.
[0043]
Next, numerical data of optical members constituting the eyepiece of the third embodiment will be shown.
Numeric data 3

[0044]
Fourth embodiment
FIG. 9 is a sectional view along an optical axis showing an optical configuration according to a fourth embodiment of a single-lens reflex camera provided with an eyepiece according to the present invention.^-1The state at the time of is shown. Note that the parallel plate-like member in FIG. 9 is obtained by rolling a penta roof prism for convenience of explanation. FIG. 10 is a diagram showing spherical aberration, field curvature, distortion, and chromatic aberration of magnification in the fourth embodiment.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown. Note that the horizontal axis of the spherical aberration and the field curvature of FIG.^-1), And the horizontal axis in the lateral chromatic aberration is the angle (minute).
The single-lens reflex camera having the eyepiece of the fourth embodiment includes a penta roof prism 7 and an eyepiece 8.
The eyepiece 8 is formed by joining a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens in order from the object side, and a first lens component 8a ′ having a positive refractive power as a whole, and A second lens component 8b having a positive refractive power composed of one positive meniscus lens having a convex surface, and a third lens component 8c ″ having a negative refractive power composed of a negative meniscus lens having a convex surface facing the subject. The diopter adjustment is performed by moving the second lens component 8b.
[0045]
Next, numerical data of optical members constituting the eyepiece of the fourth embodiment will be shown.
Numeric data 4

[0046]
Fifth embodiment
FIG. 11 is a sectional view along an optical axis showing an optical configuration according to a fifth embodiment of a single-lens reflex camera provided with an eyepiece according to the present invention.^-1The state at the time of is shown. In addition, the parallel plate-shaped member in FIG. 11 is obtained by rolling a penta roof prism for convenience of explanation. FIG. 12 is a diagram showing spherical aberration, field curvature, distortion, and chromatic aberration of magnification in the fifth embodiment.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown. Note that the horizontal axis of the spherical aberration and the field curvature of FIG.^-1), And the horizontal axis in the lateral chromatic aberration is the angle (minute).
The single-lens reflex camera provided with the eyepiece of the fifth embodiment includes a penta roof prism 7 and an eyepiece 8.
The eyepiece 8 has, in order from the object side, a first lens component 8a having a positive refractive power composed of a biconvex positive lens, and a positive refractive power composed of one positive meniscus lens having a convex surface facing the object side. It is composed of a second lens component 8b and a third lens component 8c 'which is composed of a cemented lens of a biconvex positive lens and a biconcave negative lens and has a negative refractive power as a whole. The diopter adjustment is performed by moving the second lens component 8b.
[0047]
Next, numerical data of optical members constituting the eyepiece of the fifth embodiment will be shown.
Numeric data 5

[0048]
Next, Table 1 below shows numerical values of the conditional expressions of the present invention in each embodiment.
Table 1

[0049]
Table 2 below shows element values in each embodiment.
Table 2

[0050]
As described above, the eyepiece of the present invention and the single-lens reflex camera equipped with the same have the following features in addition to the features described in the claims.
[0051]
(1) A first lens component having a positive refractive power, a second lens component having a positive refractive power composed of one meniscus lens having a convex surface facing the subject side, and a pupil-side surface in order from the subject side. An eyepiece having a third lens component having a negative refractive power as a whole, the refractive power of which is higher than the refractive power of the object-side surface, and satisfying the following conditional expression:
2.5 <fb / Y <4.0
0.4 <f1 / f <0.95
Here, fb is the air-equivalent length from the observation surface to the entrance surface of the first lens component, Y is the screen diagonal length (mm) on the observation surface, f1 is the focal length of the first lens component, and f is the diopter minus. 0.5 (m^-1) Is the focal length of the whole eyepiece system.
[0052]
(2) A first lens component having a positive refractive power, a second lens component having a positive refractive power composed of one meniscus lens having a convex surface facing the subject side, and a pupil-side surface in order from the subject side. An eyepiece having a third lens component whose refractive power is stronger than the refractive power of the surface on the object side and which has a refractive power as a whole, and which satisfies the following conditional expression:
−1.0 <f3 / f <−0.2
0.4 <f1 / f <0.95
Here, f3 is the focal length of the third lens component, f1 is the focal length of the first lens component, and f is diopter -0.5 (m^-1) Is the focal length of the whole eyepiece system.
[0053]
(3) A first lens component having a positive refractive power, a second lens component having a positive refractive power composed of one meniscus lens having a convex surface facing the subject side, and a pupil-side surface in order from the subject side. And a third lens component having a negative refractive power as a whole, the refractive power of which is greater than the refractive power of the surface on the subject side, and satisfying the following conditional expression.
0.4 <f1 / f <0.95
Here, f1 is the focal length of the first lens component, and f is diopter -0.5 (m^-1) Is the focal length of the whole eyepiece system.
[0054]
(4) The eyepiece according to any one of (1) to (3), wherein the following conditional expression is satisfied.
16.0 <Y <28.0
Here, Y is the screen diagonal length (mm) on the observation surface.
[0055]
(5) The eyepiece according to any one of (1) to (4), wherein the following conditional expression is satisfied.
0.5 <f2 / f <1.2
Here, f2 is the focal length of the second lens component, and f is diopter -0.5 (m^-1) Is the focal length of the whole eyepiece system.
[0056]
(6) The eyepiece according to any one of (1) to (5), wherein the following conditional expression is satisfied.
-1.3 <f12 / f3 <-0.9
Here, f12 is a combined focal length of the first lens component and the second lens component, and f3 is a focal length of the third lens component.
[0057]
(7) The eyepiece according to any one of (1) to (6), wherein a positive lens having an Abbe number of 80 or more is used as the first lens component.
[0058]
(8) The diopter adjustment is performed by moving the second lens component in the optical axis direction, wherein the diopter is adjusted. Eyepiece.
[0059]
(9) The eyepiece according to any one of (1) to (8), wherein the first lens component or the third lens component is formed of a cemented lens.
[0060]
(10) The eyepiece according to any one of (1) to (9), wherein the eyepiece is configured by four lenses.
[0061]
(11) A screen surface on which an image of a subject is projected, a plurality of reflecting surfaces for erecting the image on the screen surface, and an eyepiece having a positive refractive power for observing the image. A single-lens reflex camera including the eyepiece according to any one of (1) to (10).
[0062]
【The invention's effect】
According to the eyepiece of the present invention and the single-lens reflex camera provided with the same, the screen size is about half that of a 35 mm silver halide film, and the distance from the observed surface to the entrance surface of the first lens component when the focal length is f. , The eyepiece having a long finder magnification of about 1.4f, a high finder magnification, a high eye point and a good appearance, and a single-lens reflex camera having the same can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram common to each example showing an embodiment of a single-lens reflex camera provided with an eyepiece of the present invention.
FIG. 2 is a diagram for explaining elements in each conditional expression of the present invention, and shows a screen surface formed of a sand surface or the like.
FIG. 3 is a cross-sectional view along the optical axis showing an optical configuration according to a first embodiment of the single-lens reflex camera provided with the eyepiece according to the present invention, the diopter being -0.5 m;^-1The state at the time of is shown.
FIGS. 4A and 4B are diagrams showing spherical aberration, field curvature, distortion, and chromatic aberration of magnification in the first embodiment. FIG.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown.
FIG. 5 is a cross-sectional view along an optical axis showing an optical configuration according to a second embodiment of the single-lens reflex camera provided with the eyepiece according to the present invention.^-1The state at the time of is shown.
FIGS. 6A and 6B are diagrams showing spherical aberration, field curvature, distortion, and chromatic aberration of magnification in the second embodiment. FIG. 6A shows a diopter of +1 m.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown.
FIG. 7 is a cross-sectional view along an optical axis showing an optical configuration of a single-lens reflex camera including an eyepiece according to a third embodiment of the present invention, which has a diopter of -0.5 m.^-1The state at the time of is shown.
FIGS. 8A and 8B are diagrams showing spherical aberration, field curvature, distortion, and chromatic aberration of magnification in the third embodiment. FIG. 8A shows a diopter of +1 m.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown.
FIG. 9 is a cross-sectional view along an optical axis showing an optical configuration of a single-lens reflex camera including an eyepiece according to a fourth embodiment of the present invention, the diopter being -0.5 m;^-1The state at the time of is shown.
10A and 10B are diagrams showing spherical aberration, field curvature, distortion, and chromatic aberration of magnification in the fourth embodiment. FIG. 10A shows a diopter of +1 m.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown.
FIG. 11 is a cross-sectional view along an optical axis showing an optical configuration according to a fifth embodiment of the single-lens reflex camera provided with the eyepiece according to the present invention, the diopter being -0.5 m;^-1The state at the time of is shown.
12A and 12B are diagrams showing spherical aberration, field curvature, distortion, and chromatic aberration of magnification in the fifth embodiment, and FIG. 12A shows a diopter of +1 m.^-1In the case of (b), the diopter is -0.5 m^-1In (c), the diopter is -3 m^-1The state at the time of is shown.
[Explanation of symbols]
1 SLR camera
2 Shooting lens
3 Optical axis
4 CCD
5 Quick return mirror
6 Screen surface
7 penta roof prism
8 Eyepiece
8a, 8a 'First lens component having positive refractive power
8b Second lens component having positive refractive power
8c, 8c ', 8c "Third lens component having negative refractive power
9 Parallel flat plate (cover glass)
10 Observer's pupil (exit pupil)

Claims (3)

A first lens component having a positive refractive power, in order from the subject side;
A second lens component having a positive refractive power,
A third lens component having a negative refractive power,
An eyepiece lens characterized by satisfying the following conditional expression.
2.5 <fb / Y <4.0
−1.0 <f3 / f <−0.2
0.4 <f1 / f <0.95
Here, fb is the air-equivalent length from the observation surface to the entrance surface of the first lens component, Y is the screen diagonal length (mm) on the observation surface, f3 is the focal length of the third lens component, and f1 is the first lens. The focal length of the component, f, is the focal length of the whole eyepiece system at a diopter of -0.5 (m ^-1 ). A first lens component having a positive refractive power, in order from the subject side;
A second lens component having a positive refractive power and comprising one meniscus lens having a convex surface facing the subject side;
A third lens component having a negative refractive power as a whole, wherein the refractive power of the pupil-side surface is stronger than the refractive power of the subject-side surface;
An eyepiece lens characterized by satisfying the following conditional expression.
2.5 <fb / Y <4.0
−1.0 <f3 / f <−0.2
0.4 <f1 / f <0.95
Here, fb is the air-equivalent length from the observation surface to the entrance surface of the first lens component, Y is the screen diagonal length (mm) on the observation surface, f3 is the focal length of the third lens component, and f1 is the first lens. The focal length of the component, f, is the focal length of the whole eyepiece system at a diopter of -0.5 (m ^-1 ). A single-lens reflex including a screen surface on which an image of a subject is projected, a plurality of reflecting surfaces for erecting the image on the screen surface, and an eyepiece having a positive refractive power for observing the image. In the camera,
A single-lens reflex camera comprising the eyepiece according to claim 1.

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