JP2017068129A - Ocular lens, optical device, and method of manufacturing ocular lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an eyepiece with high magnification and capable of correcting various aberrations satisfactorily. A first lens L1 having a positive refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, arranged in order from the observation object side, and a positive An ocular lens is configured with the fourth lens L4 having refractive power. This eyepiece satisfies the following conditional expression. 0.80 <f4 / fe <2.20 where f4 is the focal length of the fourth lens, and fe is the focal length when the diopter of the eyepiece is −1 [1 / m]. [Selection] Figure 1

Description

  The present invention relates to an eyepiece, an optical apparatus using the eyepiece, and a method for manufacturing the eyepiece.

  Conventionally, an eyepiece used for an electronic viewfinder has been proposed (see, for example, Patent Document 1). However, the conventional eyepieces as described above have a problem that it is difficult to achieve good optical performance when high magnification is required.

JP 2007-225835 A

The eyepiece according to the present invention includes a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, arranged in order from the observation object side, and a positive lens. A fourth lens having a refractive power of 1 and satisfies the following conditional expression.
0.80 <f4 / fe <2.20
Where f4: focal length of the fourth lens,
fe: Focal length when the eyepiece diopter is -1 [1 / m].

  An optical apparatus according to the present invention is configured by mounting the above eyepiece.

  A manufacturing method according to the present invention is a method of manufacturing an eyepiece for observing an observation object. The eyepiece is arranged in order from the observation object side, a first lens having a positive refractive power, and a negative refraction. A second lens having a positive power, a third lens having a positive refractive power, and a fourth lens having a positive refractive power, and each lens is disposed so as to satisfy the following conditional expression: Manufactured.

0.80 <f4 / fe <2.20
Where f4: focal length of the fourth lens,
fe: Focal length when the eyepiece diopter is -1 [1 / m].

It is sectional drawing which shows the lens structure of the eyepiece which concerns on 1st Example. 2 (a), 2 (b) and 2 (c) respectively show -4 [1 / m] when the diopter of the eyepiece according to the first example is -1 [1 / m]. FIG. 4 is various aberration diagrams at the time of +4 [1 / m]. It is sectional drawing which shows the lens structure of the eyepiece which concerns on 2nd Example. 4 (a), 4 (b), and 4 (c) are respectively -4 [1 / m] when the diopter of the eyepiece according to the second example is -1 [1 / m]. FIG. 4 is various aberration diagrams at the time of +4 [1 / m]. It is sectional drawing which shows the lens structure of the eyepiece which concerns on 3rd Example. 6 (a), 6 (b) and 6 (c) respectively show -4 [1 / m] when the diopter of the eyepiece according to the third example is -1 [1 / m]. FIG. 4 is various aberration diagrams at the time of +4 [1 / m]. It is sectional drawing which shows the lens structure of the eyepiece which concerns on 4th Example. 8 (a), 8 (b) and 8 (c) respectively show -4 [1 / m] when the diopter of the eyepiece according to the fourth example is -1 [1 / m]. FIG. 4 is various aberration diagrams at the time of +4 [1 / m]. It is sectional drawing which shows the lens structure of the eyepiece which concerns on 5th Example. 10 (a), 10 (b) and 10 (c) respectively show -4 [1 / m] when the diopter of the eyepiece according to the fifth example is -1 [1 / m]. FIG. 4 is various aberration diagrams at the time of +4 [1 / m]. It is sectional drawing which shows the lens structure of the eyepiece which concerns on 6th Example. 12 (a), 12 (b), and 12 (c) are respectively -4 [1 / m] when the diopter of the eyepiece according to the sixth example is -1 [1 / m]. FIG. 4 is various aberration diagrams at the time of +4 [1 / m]. It is sectional drawing which shows the lens structure of the eyepiece which concerns on 7th Example. 14 (a), 14 (b) and 14 (c) respectively show -4 [1 / m] when the diopter of the eyepiece according to the seventh example is -1 [1 / m]. FIG. 4 is various aberration diagrams at the time of +4 [1 / m]. It is sectional drawing which shows the lens structure of the eyepiece which concerns on 8th Example. 16 (a), 16 (b) and 16 (c) are respectively -3 [1 / m] when the diopter of the eyepiece according to the eighth example is -1 [1 / m]. FIG. 6 is various aberration diagrams at the time of +3 [1 / m]. It is sectional drawing which shows the lens structure of the eyepiece which concerns on 9th Example. 18 (a), 18 (b), and 18 (c) are respectively -3 [1 / m] when the diopter of the eyepiece according to the ninth example is -1 [1 / m]. FIG. 6 is various aberration diagrams at the time of +3 [1 / m]. It is a figure which shows the structure of the camera provided with the eyepiece of this embodiment. It is a flowchart which shows the outline of the manufacturing method of the eyepiece of this embodiment.

  Hereinafter, an eyepiece lens, an optical apparatus, and a method for manufacturing the eyepiece lens according to the present embodiment will be described with reference to the drawings. First, the eyepiece according to the embodiment will be described.

The eyepiece according to the present embodiment is an eyepiece for enlarging and observing an observation object. Here, the observation object is an intermediate image by an objective lens, or a display surface of an image display element such as a liquid crystal display element or an organic EL (Electroluminescence) display, and is particularly preferably a display surface of the liquid crystal display element. Therefore, the eyepiece according to this embodiment is suitable for use in an electronic viewfinder for observing an image displayed on the display surface of the image display element. In the following description, an observation object is also referred to as an “observation object plane”.

  In the following description of the embodiments and examples, [1 / m] is used as the diopter that is a unit of diopter. For example, the diopter X [1 / m] indicates a state in which an image by the eyepiece lens can be located at a position of 1 / X [m (meter)] on the optical axis from the eye point. Note that the sign is positive when the image is formed on the eye point side of the eyepiece.

  For example, as shown in FIG. 1, the eyepiece LE according to this embodiment includes a first lens L1 having a positive refractive power and a first lens L1 having a negative refractive power, which are arranged in order from the object (observation object Ob) side. An eyepiece lens LE (1) having two lenses L2, a third lens L3 having a positive refractive power, and a fourth lens L4 having a positive refractive power is applicable. The eyepiece lens LE according to the present embodiment includes an eyepiece lens LE (2) shown in FIG. 3, an eyepiece lens LE (3) shown in FIG. 5, an eyepiece lens LE (4) shown in FIG. 7, and an eyepiece lens LE shown in FIG. (5), an eyepiece lens LE (6) shown in FIG. 11, an eyepiece lens LE (7) shown in FIG. 13, an eyepiece lens LE (8) shown in FIG. 15, and an eyepiece lens LE (9) shown in FIG.

  As described above, the eyepiece LE according to the present embodiment includes the first lens L1 having a positive refractive power in order to enlarge and observe the observation object. In this eyepiece lens LE, a second lens L2 having a negative refractive power is disposed in order to correct chromatic aberration, curvature of field and astigmatism generated in the first lens L1 having a positive refractive power. Further, the eyepiece lens LE includes a third lens L3 having a positive refractive power and a fourth lens L4 having a positive refractive power in order to satisfactorily correct coma and distortion.

  The eyepiece lens LE according to the present embodiment can correct various aberrations and achieve high magnification by adopting such a configuration. For example, in order to enlarge and observe an observation object having a diagonal length of around 10 mm, it is possible to achieve a high magnification with an apparent viewing angle of 30 ° or more.

  Under the above configuration, the eyepiece lens LE {LE (1) to LE (9)} according to the present embodiment satisfies the following conditional expression (1).

0.80 <f4 / fe <2.20 (1)
Where f4: focal length of the fourth lens,
fe: Focal length when the eyepiece diopter is -1 [1 / m].

  Conditional expression (1) is for making the refractive power of the fourth lens L4 within an appropriate range. By satisfying (1) with this conditional expression, the refractive power of the fourth lens L4 is made appropriate. Good aberration correction (coma aberration, distortion aberration correction, etc.) can be performed.

  If the lower limit of conditional expression (1) is not reached, the refractive power of the fourth lens L4 increases, the Petzval sum increases, and it becomes difficult to simultaneously correct curvature of field and astigmatism. In addition, it becomes difficult to correct coma. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.95. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 1.10. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 1.20.

  When the upper limit of conditional expression (1) is exceeded, the refractive power of the fourth lens L4 becomes small, and it becomes difficult to correct various aberrations, particularly coma. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 2.05. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 1.92. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 1.60.

It is also desirable for the eyepiece lens LE according to the present embodiment to satisfy the following conditional expression (2).
-1.73 <(R4b + R4a) / (R4b-R4a) <-0.35 (2)
Where R4b: radius of curvature of the fourth lens on the eye point side,
R4a: radius of curvature of the fourth lens on the observation object side.

  Conditional expression (2) is a condition for making the shape of the fourth lens L4 appropriate. By satisfying this conditional expression (2), the shape of the fourth lens L4 is made appropriate. Good aberration correction can be performed.

If the lower limit value of conditional expression (2) is not reached, the shape of the fourth lens L4 deviates from an appropriate range, and it becomes difficult to correct various aberrations, particularly spherical aberration and coma aberration. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to −1.67. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (2) to −1.63. In order to further secure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (2) to -1.30.

  Even if the upper limit of conditional expression (2) is exceeded, the shape of the fourth lens L4 deviates from an appropriate range, and it becomes difficult to correct various aberrations, particularly spherical aberration and coma. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to −0.70. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of conditional expression (2) to −0.80. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to −0.90.

It is also desirable for the eyepiece lens LE according to the present embodiment to satisfy the following conditional expression (3).
−4.00 <(R3b + R3a) / (R3b−R3a) <− 0.95 (3)
Where R3b: radius of curvature of the third lens on the eye point side,
R3a: radius of curvature of the third lens on the observation object side.

  Conditional expression (3) is a condition for making the shape of the third lens L3 appropriate. By satisfying this conditional expression (3), the shape of the third lens L3 is made appropriate. Good aberration correction can be performed.

  If the lower limit value of conditional expression (3) is not reached, the shape of the third lens L3 deviates from an appropriate range, and it becomes difficult to correct various aberrations, particularly coma aberration and field curvature. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to −3.70. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to −3.40. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to −3.20.

  Even if the upper limit value of conditional expression (3) is exceeded, the shape of the third lens L3 deviates from an appropriate range, and it becomes difficult to correct various aberrations, particularly coma aberration and field curvature. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to −1.05. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to −1.15. In order to further secure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (3) to -1.30.

It is also desirable for the eyepiece lens LE according to the present embodiment to satisfy the following conditional expression (4).
1.40 <f3 / fe <4.80 (4)
Where f3: focal length of the third lens,
fe: Focal length when the eyepiece diopter is -1 [1 / m].

  Conditional expression (4) is a condition for defining the refractive power of the third lens L3 within an appropriate range. By satisfying (4) with this conditional expression, the refractive power of the third lens L3 is set appropriately. As a result, good aberration correction can be performed.

  If the lower limit of conditional expression (4) is not reached, the refractive power of the third lens L3 deviates from an appropriate range, and it becomes difficult to correct spherical aberration, coma aberration, and field curvature. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 1.58. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 1.73. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 1.90.

Even if the upper limit of conditional expression (4) is exceeded, the refractive power of the third lens L3 deviates from an appropriate range, and it becomes difficult to correct spherical aberration, coma aberration, and field curvature. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 4.60. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 4.40. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 4.20.

It is also desirable for the eyepiece lens LE according to the present embodiment to satisfy the following conditional expression (5).
0.22 <Y0 / fe <0.40 (5)
Where Y0 is the height of the observation object,
fe: Focal length when the eyepiece diopter is -1 [1 / m].

  Conditional expression (5) defines a condition for defining an appropriate range with respect to the ratio of the diagonal length of the observation object and the focal length of the eyepiece lens LE. By satisfying (5), the conditional expression (5) It is possible to reduce the size of the eyepiece while securing the magnification and to perform good aberration correction.

  If the lower limit value of conditional expression (5) is not reached, the magnification of the eyepiece lens LE becomes small and a high magnification cannot be secured. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.24. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.26. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.28.

  If the upper limit of conditional expression (5) is exceeded, it will be difficult to correct field curvature, astigmatism and coma. Further, the outer diameter of the eyepiece lens LE is increased. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.36. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.33. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.31.

It is also desirable for the eyepiece lens LE according to the present embodiment to satisfy the following conditional expression (6).
0.45 <(− f2) / fe <1.10 (6)
Where f2: focal length of the second lens,
fe: Focal length when the eyepiece diopter is -1 [1 / m].

  Conditional expression (6) defines a condition for setting the refractive power of the second lens L2 within an appropriate range. By satisfying the conditional expression (6), the refractive power of the second lens L2 is made appropriate. Therefore, good aberration correction can be performed.

  If the lower limit value of conditional expression (6) is not reached, the refractive power of the second lens L2 becomes large and it becomes difficult to correct coma. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.55. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.65. In order to further secure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.75.

  If the upper limit of conditional expression (6) is exceeded, the Petzval sum increases, making it difficult to correct curvature of field and astigmatism simultaneously. In addition, it is difficult to correct coma. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (6) to 1.00. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (6) to 0.95. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (6) to 0.87.

It is also desirable for the eyepiece lens LE according to the present embodiment to satisfy the following conditional expression (7).
1.20 <f4 / (− f2) <2.80 (7)
Where f2: focal length of the second lens,
f4: focal length of the fourth lens.

  Conditional expression (7) defines a condition for setting the ratio of the refractive power of the fourth lens L4 and the refractive power of the second lens L2 to an appropriate range. By satisfying the conditional expression (7), Good aberration correction can be performed.

  If the lower limit of conditional expression (7) is not reached, the refractive power of the fourth lens with respect to the second lens will increase, the Petzval sum will increase, and it will be difficult to correct curvature of field and astigmatism simultaneously. In addition, it is difficult to correct coma. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (7) to 1.35. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (7) to 1.45. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (7) to 1.52.

  If the upper limit of conditional expression (7) is exceeded, it will be difficult to correct coma and distortion. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (7) to 2.77. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (7) to 2.72. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (7) to 2.30.

It is also desirable for the eyepiece lens LE according to the present embodiment to satisfy the following conditional expression (8).
0.40 <ΣD12 / fe <0.60 (8)
However, ΣD12: distance on the optical axis from the lens surface on the observation object side of the first lens to the lens surface on the eye point side of the second lens
fe: Focal length when the eyepiece diopter is -1 [1 / m].

  Conditional expression (8) defines a condition for setting the distance on the optical axis from the lens surface on the observation object side of the first lens L1 to the lens surface on the eye point side of the second lens L2 within an appropriate range, Satisfying the conditional expression (8) makes it possible to correct aberrations satisfactorily while reducing the thickness of the eyepiece on the optical axis.

  If the lower limit of conditional expression (8) is not reached, it will be difficult to correct field curvature and coma. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.43. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.45. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.48.

  Exceeding the upper limit of conditional expression (8) makes it difficult to correct field curvature and coma. Further, the thickness of the eyepiece lens LE in the optical axis direction is increased. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (8) to 0.58. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (8) to 0.55. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (8) to 0.52.

It is also desirable for the eyepiece lens LE according to the present embodiment to satisfy the following conditional expression (9).
0.05 <D2 / fe <0.20 (9)
Where D2: the thickness of the second lens on the optical axis,
fe: Focal length when the eyepiece diopter is -1 [1 / m].

Conditional expression (9) defines a condition for setting the thickness of the second lens L2 on the optical axis within an appropriate range. By satisfying (9), this conditional expression satisfies the condition on the optical axis of the eyepiece lens. Good aberration correction can be performed while reducing the thickness.

  If the lower limit of conditional expression (9) is not reached, it will be difficult to correct field curvature and coma. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (9) to 0.07. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (9) to 0.08. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (9) to 0.09.

  Exceeding the upper limit of conditional expression (9) makes it difficult to correct field curvature and coma. Further, the thickness of the eyepiece lens LE in the optical axis direction is increased. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (9) to 0.17. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (9) to 0.14. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (9) to 0.10.

  In the eyepiece lens LE according to the present embodiment, it is preferable that at least one surface of the first lens L1 is an aspherical surface. Thereby, curvature of field, astigmatism, and coma can be favorably corrected.

  In the eyepiece lens LE according to the present embodiment, it is preferable that all of the first to fourth lenses constituting the eyepiece lens LE each have an aspheric surface on at least one surface. Thereby, curvature of field, astigmatism, and coma can be favorably corrected.

  In the eyepiece lens LE according to the present embodiment, it is preferable that at least one of the first to fourth lenses is a plastic lens. Thereby, the weight reduction and cost reduction of an eyepiece lens can be achieved. In addition, since an aspherical shape can be easily formed, spherical aberration, curvature of field, astigmatism, coma aberration, and distortion can be corrected well.

  In the eyepiece lens LE according to the present embodiment, the diopter adjustment is preferably performed by moving the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 along the optical axis. . As a result, various aberrations during diopter adjustment, in particular, variations in curvature of field, coma, and distortion can be reduced.

  In the eyepiece lens LE according to this embodiment, the diopter adjustment may be performed by integrally moving all the lenses constituting the eyepiece lens LE. As a result, various aberrations during diopter adjustment, in particular, variations in field curvature, coma aberration, and distortion can be reduced.

  The optical apparatus according to this embodiment includes the eyepiece lens having the above-described configuration. As a specific example, a camera 1 (optical apparatus) provided with the eyepiece lens LE will be described with reference to FIG. The camera 1 is a digital camera including an objective lens OL, an image sensor C such as a CCD or a CMOS, and an electronic viewfinder EVF. The electronic viewfinder EVF includes an image display element such as a liquid crystal display element, which is an observation object Ob, and an eyepiece optical system EL for magnifying and observing an image displayed on the image display element. The camera 1 is equipped with the eyepiece according to the first embodiment (or the second to ninth embodiments) as the eyepiece optical system EL.

  In the camera 1 having such a configuration, light from an object (subject) (not shown) is collected by the objective lens OL and formed on the image sensor C to form an image of the subject. The image of the subject imaged on the image sensor C is captured by the image sensor C, and the image of the subject imaged by the image sensor C is displayed on the image display element that is the observation object Ob. The photographer can enlarge and observe the image of the object (subject) formed by the objective lens OL via the eyepiece optical system EL by positioning the eye at the eye point EP.

  When a release button (not shown) is pressed by the photographer, an image corresponding to the image captured by the image sensor C at this time, that is, the image displayed on the image display element observed through the eyepiece optical system EL is displayed. The image of the object (subject) is stored in a memory (not shown). In this way, the photographer can shoot an object (subject) with the camera 1.

  According to the camera 1 as described above, by providing the eyepiece lens according to the first embodiment (or the second to ninth embodiments) as the eyepiece optical system EL, it has a high magnification, a small size and high optical performance. A camera having an eyepiece optical system can be realized. Even when the zoom optical system according to each of the above embodiments is mounted on a camera having a quick return mirror, the same effect as the camera 1 can be obtained. Moreover, you may mount the eyepiece which concerns on the said 1st-9th Example as eyepiece optical system EL of the finder apparatus which can be attached or detached to a camera main body. A camera equipped with such a viewfinder device can also achieve the same effects as the camera 1 described above.

  Next, a method for manufacturing the eyepiece according to this embodiment will be described. FIG. 20 is a diagram showing an outline of a method for manufacturing an eyepiece according to this embodiment.

The eyepiece lens manufacturing method according to the present embodiment is an eyepiece lens manufacturing method for observing an observation object, and includes the following steps ST1 and ST2 as shown in FIG.
Step S1: From the observation object side, a first lens L1 having a positive refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, and a fourth lens having a positive refractive power Arranged in the order of L4.
Step S2: The first to fourth lenses L1 to L4 are configured to satisfy at least the conditional expression (1).

  According to the eyepiece manufacturing method of the present embodiment, an eyepiece having a high magnification, a small size, and high optical performance can be realized. In particular, an eyepiece lens suitable for use in an electronic viewfinder for observing an image displayed on the image display element can be realized.

  Hereinafter, the configuration and aberration of the eyepiece according to examples (first to ninth examples) of the present embodiment will be described with reference to lens cross-sectional views and aberration diagrams shown in FIGS. In the lens cross-sectional view, each lens is represented by a combination of a symbol L and a number. In the surface number, the display surface of the observation object Ob is the first surface, the surface on the observation object side of the first lens L1 is the second surface, and the surface numbers are given in order toward the eye point side. In this case, in order to prevent complications due to an increase in types and numbers of codes and numbers, lenses and the like are represented using combinations of codes and numbers independently for each embodiment. For this reason, the combination of the same code | symbol and number is used between Examples, but each of each Example is independent and does not mean that it is the same structure.

  Tables 1 to 9 are shown below, and these are tables showing each specification data in the first to ninth examples.

  In [Overall specifications], Y0 is the height of the observation object, TL is the optical axis from the observation object surface to the lens surface closest to the eye point EP of the eyepiece when the diopter is -1 [1 / m]. Each distance above is shown.

In [Lens Specifications], the surface number is the order of the optical surfaces counted from the observation object side, and R is the radius of curvature (
The surface where the center of curvature is located on the image side is a positive value), D is the surface interval (interval from the relevant surface to the next), nd is the refractive index with respect to the d-line (wavelength 587.6 nm), and νd is d The Abbe numbers for the lines (wavelength 587.6 nm) are shown. The first surface shows an observation object surface, that is, a display surface of the liquid crystal display element that is the observation object Ob. EP indicates an eye point EP. A radius of curvature R = ∞ represents a plane. The description of the refractive index of air nd = 1.000 is omitted. When the lens surface is an aspherical surface, the surface number is marked with * and the radius of curvature R column indicates the paraxial radius of curvature.

In the table of [Aspherical data], the shape of the aspherical surface (optical surface with a symbol * after the surface number) shown in [Lens Specification] is shown by the following equation (a). X (y) is the distance along the optical axis direction from the tangential plane at the apex of the aspheric surface to the position on the aspheric surface at height y (zag amount), and R is the radius of curvature of the reference sphere (paraxial curvature radius) , Κ is the conic constant, and Ai is the i-th aspherical coefficient. “E-n” indicates “× 10 ⁻ⁿ ”. For example, 1.234E-05 = 1.234 × 10 ⁻⁵ . The secondary aspheric coefficient A2 is 0, and the description thereof is omitted.

X (y) = (y ² / r) / [1+ {1-κ (y ² / r ² )} ^1/2 ] + A4y ⁴ + A6y ⁶ +
A8y ⁸ + A10y ¹⁰ (a)

In [variable interval data], fe indicates the focal length of the eyepiece at each diopter, and indicates the surface interval for each diopter with the surface number at which the surface interval is “variable”. For example, in the first embodiment, the first lens L1 that is the next surface from the display surface (first surface) of the liquid crystal display element that is the observation object Ob.
A surface distance D1 to the surface (second surface) on the observation object side and a surface distance D9 from the eye point side surface (9th surface) of the fourth lens L4 indicated by surface number 9 to the eye point EP are shown.

  [Conditional Expression Corresponding Value] indicates the corresponding value of each conditional expression.

  Hereinafter, in all the specification values, “mm” is generally used for the focal length f, curvature radius R, surface distance D, and other lengths, etc. unless otherwise specified, but the optical system is proportionally enlarged. Alternatively, the same optical performance can be obtained even by proportional reduction, and the present invention is not limited to this.

  The description of the table so far is common to all the embodiments, and the description below is omitted.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 and 2 and Table 1. FIG. As shown in FIG. 1, the eyepiece according to the present example, in order from the observation object Ob side, is a first lens L1 that is a positive lens and a second lens that is a negative meniscus lens having a convex surface facing the eyepoint EP side. L2, a third lens L3 that is a positive meniscus lens having a convex surface facing the eye point EP, and a fourth lens L4 that is a positive meniscus lens having a convex surface facing the eye point EP.

  In the eyepiece according to the present example, the lens surfaces on the observation object Ob side and the lens surfaces on the eye point EP side of all the first to fourth lenses L1 to L4 are aspherical lenses. In this eyepiece lens, diopter adjustment is performed by moving the first to fourth lenses L1 to L4 integrally along the optical axis.

  Table 1 below lists values of specifications of the optical system according to the first example.

(Table 1) First Example [Overall Specifications]
Y0 = 5
TL = 22.86170
[Lens specifications]
Surface number RD nd νd
1) ∞ (variable) 1.0000
2) * 72.5788 4.7000 1.5439 55.9
3) * -8.0000 1.9500 1.0000
4) * -6.3662 1.6000 1.6425 22.47
5) * -24.6853 0.3000 1.0000
6) * -40.0000 2.9000 1.5439 55.9
7) * -19.5000 0.3000 1.0000
8) * -2273.2089 4.5000 1.5439 55.9
9) * -11.4425 (variable) 1.0000
EP

[Aspherical data]
κ A4 A6 A8 A10
2nd surface 1.0000 -1.03862E-04 7.15276E-07 -1.27444E-08 0.00000E + 00
3rd surface 0.2300 2.34280E-04 -6.93507E-06 1.23236E-07 -1.14925E-09
4th surface 0.2000 -1.07794E-05 -7.79605E-06 1.41682E-07 -1.29523E-09
5th surface 2.4384 -4.99050E-05 1.67054E-07 5.46646E-09 -3.67819E-11
6th surface 1.0000 3.54231E-05 -2.74085E-07 -1.00000E-09 -5.00000E-11
7th surface 0.9929 -4.96717E-05 3.49183E-07 1.38361E-10 -7.74058E-11
8th surface 1.0000 2.90420E-05 3.43404E-08 -3.19969E-09 4.30546E-11
9th surface -1.3000 -4.88522E-05 3.57297E-07 -2.59749E-09 3.79684E-11

[Variable interval data]
Diopter -1 -4 +4
fe 16.71168 16.71168 16.71168
D1 6.61170 5.73830 7.98440
D9 20.00000 20.88304 18.63568

[Conditional expression values]
-F2 = 13.82429
f3 = 66.63213
f4 = 21.12878
fe = 16.71168
D2 = 1.60000
ΣD12 = 8.25000
Conditional expression (1) f4 / fe = 1.26431
Conditional expression (2) (R4b + R4a) / (R4b−R4a) = − 1.01012
Conditional expression (3) (R3b + R3a) / (R3b-R3a) = − 2.90244
Conditional expression (4) f3 / fe = 3.98716
Conditional expression (5) Y0 / fe = 0.29919
Conditional expression (6) (−f2) /fe=0.82722
Conditional expression (7) f4 / (− f2) = 1.52838
Conditional expression (8) ΣD12 / fe = 0.49367
Conditional expression (9) D2 / fe = 0.09574

2 (a), 2 (b), and 2 (c) respectively show the eyepiece according to the first example when the diopter is -1 [1 / m], -4 [1 / m], FIG. 6 is a diagram showing various aberrations at +4 [1 / m].

  In each aberration diagram, Y1 represents the height at which light emitted from the center of the optical axis of the observation object is incident on the tangential plane of the first lens L1 on the observation object side, and Y0 represents the height of the observation object. In the figure, d indicates an aberration curve at the d-line (wavelength λ = 587.6 nm), g is the g-line (wavelength λ = 435.8 nm), C is the C-line (wavelength λ = 656.3 nm), and F is An aberration curve at F line (wavelength λ = 486.1 nm) is shown. In the aberration diagram showing astigmatism, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. The unit D on the horizontal axis of the spherical aberration diagram and the astigmatism diagram is [1 / m] (diopter). The coma aberration indicates the coma aberration at each height position of the observation object, and shows the entire coma aberration at the bottom and the coma aberration at the optical axis position (Y0 = RAND) from the bottom. In the various aberration diagrams of the following examples, the same reference numerals as those of the present example are used.

  From each aberration diagram, it can be seen that the eyepiece according to the first example has excellent optical performance with various aberrations corrected well within the diopter adjustment range.

(Second embodiment)
A second embodiment will be described with reference to FIGS. 3 and 4 and Table 2. FIG. As shown in FIG. 3, the eyepiece according to the present example, in order from the observation object Ob side, is a first lens L1 that is a positive lens, and a second lens that is a negative meniscus lens having a convex surface facing the eye point EP side. L2, a third lens L3 that is a positive meniscus lens having a convex surface facing the eye point EP, and a fourth lens L4 that is a positive meniscus lens having a convex surface facing the eye point EP.

  In the eyepiece according to the present example, the lens surfaces on the observation object Ob side and the lens surfaces on the eye point EP side of all the first to fourth lenses L1 to L4 are aspherical lenses. In this eyepiece lens, diopter adjustment is performed by moving the first to fourth lenses L1 to L4 integrally along the optical axis.

  Table 2 below lists values of specifications of the optical system according to the second example.

(Table 2) Second Example [Overall Specifications]
Y0 = 5
TL = 22.96150

[Lens specifications]
Surface number RD nd νd
1) ∞ (variable) 1.0000
2) * 50.9909 4.8500 1.5311 55.91
3) * -7.7231 1.9000 1.0000
4) * -6.2569 1.6000 1.6425 22.47
5) * -25.0131 0.4000 1.0000
6) * -39.1557 3.6000 1.5311 55.91
7) * -14.5000 0.3000 1.0000
8) * -78.0498 3.8000 1.5311 55.91
9) * -11.9929 (variable) 1.0000
EP

[Aspherical data]
κ A4 A6 A8 A10
2nd surface 1.0000 -1.34059E-04 1.05744E-06 -3.57602E-08 0.00000E + 00
3rd surface 0.2300 2.05463E-04 -5.19492E-06 6.90409E-08 -7.37039E-10
4th surface 0.2000 -2.00817E-05 -5.70535E-06 1.05087E-07 -5.69098E-10
5th surface 3.4603 -4.73751E-05 2.17737E-07 8.09416E-09 -3.19170E-12
6th surface 1.0000 2.31418E-05 -8.93642E-07 8.06580E-09 -1.05880E-10
7th surface 0.4857 -2.68197E-05 1.98747E-07 4.18935E-09 -9.95479E-11
8th surface 1.0000 3.82708E-05 -1.07489E-07 -2.76436E-09 2.64196E-11
9th surface -1.3000 -5.09803E-05 -4.32938E-08 -7.46402E-10 7.37303E-12

[Variable interval data]
Diopter -1 -4 +4
fe 16.70488 16.70488 16.70488
D1 6.51150 5.63700 7.88150
D9 20.00000 20.88417 18.63837

[Conditional expression values]
-F2 = 13.43535
f3 = 41.26789
f4 = 26.15910
fe = 16.70488
D2 = 1.60000
ΣD12 = 8.35000
Conditional expression (1) f4 / fe = 1.56596
Conditional expression (2) (R4b + R4a) / (R4b-R4a) =-1.36311
Conditional expression (3) (R3b + R3a) / (R3b−R3a) = − 2.17620
Conditional expression (4) f3 / fe = 2.47041
Conditional expression (5) Y0 / fe = 0.29931
Conditional expression (6) (−f2) /fe=0.80428
Conditional expression (7) f4 / (− f2) = 1.94704
Conditional expression (8) ΣD12 / fe = 0.49985
Conditional expression (9) D2 / fe = 0.09578

  4 (a), 4 (b) and 4 (c) respectively show the eyepiece according to the second example when the diopter is -1 [1 / m], -4 [1 / m], and FIG. 6 is a diagram showing various aberrations at +4 [1 / m]. From the respective aberration diagrams, it can be seen that the eyepiece according to the second example has excellent optical performance with various aberrations corrected well within the diopter adjustment range.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 5 and 6 and Table 3. FIG. As shown in FIG. 5, the eyepiece according to the present example, in order from the observation object Ob side, is a first lens L1 that is a positive lens and a second lens that is a negative meniscus lens having a convex surface facing the eyepoint EP side. L2, a third lens L3 that is a positive meniscus lens having a convex surface facing the eye point EP, and a fourth lens L4 that is a positive lens.

  In the eyepiece according to the present example, the lens surfaces on the observation object Ob side and the lens surfaces on the eye point EP side of all the first to fourth lenses L1 to L4 are aspherical lenses. In this eyepiece lens, diopter adjustment is performed by moving the first to fourth lenses L1 to L4 integrally along the optical axis.

  Table 3 below lists values of specifications of the optical system according to the third example.

(Table 3) Third Example [Overall Specifications]
Y0 = 5
TL = 22.92140

[Lens specifications]
Surface number RD nd νd
1) ∞ (variable) 1.0000
2) * 130.3119 4.5000 1.5311 55.91
3) * -7.0993 2.0500 1.0000
4) * -5.9000 1.6000 1.6425 22.47
5) * -22.7817 0.3000 1.0000
6) *-36.2116 2.9000 1.5311 55.91
7) *-18.8432 0.3000 1.0000
8) * 1906.6621 4.6000 1.5311 55.91
9) * -11.1767 (variable) 1.0000
EP

[Aspherical data]
κ A4 A6 A8 A10
2nd surface 69.553 -1.43627E-05 8.15718E-07 -1.93365E-08 0.00000E + 00
3rd surface 0.2334 3.78587E-04 -5.03354E-06 7.45344E-08 -7.07283E-10
4th surface 0.2037 1.54146E-04 -8.27379E-06 1.80205E-07 -1.84017E-09
5th surface 2.4677 -5.20373E-05 2.55941E-07 1.36037E-08 -7.47437E-11
6th surface 2.0026 3.88308E-05 -5.16255E-07 -1.00000E-09 -5.00000E-11
7th surface 0.4177 -3.92241E-05 4.56819E-07 2.91734E-09 -1.66809E-10
8th surface 1.0000 3.01174E-05 2.05239E-07 -5.92202E-09 8.49274E-11
9th surface -1.0000 -2.87648E-05 3.43384E-07 -1.05752E-08 1.38094E-10

[Variable interval data]
Diopter -1 -4 +4
fe 16.86887 16.86887 16.86887
D1 6.67140 5.78190 8.07060
D9 20.00000 20.89932 18.60936

[Conditional expression values]
-F2 = 12.86934
f3 = 69.92228
f4 = 20.93921
fe = 16.86887
D2 = 1.60000
ΣD12 = 8.15000
Conditional expression (1) f4 / fe = 1.24129
Conditional expression (2) (R4b + R4a) / (R4b−R4a) = − 0.98834
Conditional expression (3) (R3b + R3a) / (R3b-R3a) = − 3.16983
Conditional expression (4) f3 / fe = 4.14505
Conditional expression (5) Y0 / fe = 0.29640
Conditional expression (6) (−f2) /fe=0.76290
Conditional expression (7) f4 / (-f2) = 1.62706
Conditional expression (8) ΣD12 / fe = 0.48314
Conditional expression (9) D2 / fe = 0.09485

  6 (a), 6 (b) and 6 (c) respectively show the eyepiece according to the third example when the diopter is -1 [1 / m], -4 [1 / m], and FIG. 6 is a diagram showing various aberrations at +4 [1 / m]. From the aberration diagrams, it can be seen that the eyepiece according to the third example has excellent optical performance with various aberrations corrected well within the diopter adjustment range.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. 7 and 8 and Table 4. FIG. As shown in FIG. 7, the eyepiece according to the present example, in order from the observation object Ob side, is a first lens L1 that is a positive lens, and a second lens that is a negative meniscus lens having a convex surface facing the eye point EP side. L2, a third lens L3 that is a positive meniscus lens having a convex surface facing the eye point EP, and a fourth lens L4 that is a positive meniscus lens having a convex surface facing the eye point EP.

  In the eyepiece according to the present example, the lens surfaces on the observation object Ob side and the lens surfaces on the eye point EP side of all the first to fourth lenses L1 to L4 are aspherical lenses. In this eyepiece lens, diopter adjustment is performed by moving the first to fourth lenses L1 to L4 integrally along the optical axis.

  Table 4 below provides values of specifications of the optical system according to the fourth example.

(Table 4) Fourth Example [Overall Specifications]
Y0 = 5
TL = 22.93580

[Lens specifications]
Surface number RD nd νd
1) ∞ (variable) 1.0000
2) * 42.9252 4.8500 1.5439 55.9
3) * -7.9198 1.9500 1.0000
4) * -6.4618 1.6000 1.6425 22.47
5) * -24.9149 0.3000 1.0000
6) * -37.0000 2.9000 1.5439 55.9
7) * -19.0054 0.3000 1.0000
8) * -1000.0000 4.5000 1.5439 55.9
9) * -11.7647 (variable) 1.0000
EP

[Aspherical data]
κ A4 A6 A8 A10
2nd surface 1.0000 -1.06231E-04 2.70521E-07 -2.20809E-08 0.00000E + 00
3rd surface 0.1537 2.31014E-04 -5.96662E-06 7.52290E-08 -6.60354E-10
4th surface 0.1855 2.66642E-05 -6.91471E-06 1.27635E-07 -9.97292E-10
5th surface 1.9555 -4.14761E-05 2.75619E-07 3.34151E-09 -3.08804E-11
6th surface 1.0000 4.42886E-05 -1.74945E-07 -1.00000E-09 -5.00000E-11
7th surface 1.1704 -5.45558E-05 3.45853E-07 1.04344E-09 -7.47479E-11
8th surface 1.0000 3.06121E-05 -3.99346E-08 -4.51761E-09 5.50660E-11
9th surface -1.3047 -2.81417E-05 2.69855E-07 -3.87566E-09 4.41879E-11

[Variable interval data]
Diopter -1 -4 +4
fe 16.22154 16.22154 16.22154
d1 6.53580 5.69370 7.81230
d2 23.00000 23.83829 21.72035

[Conditional expression values]
−f2 = 14.05589
f3 = 67.98575
f4 = 21.85196
fe = 16.222154
D2 = 1.60000
ΣD12 = 8.40000
Conditional expression (1) f4 / fe = 1.34710
Conditional expression (2) (R4b + R4a) / (R4b-R4a) =-1.02381
Conditional expression (3) (R3b + R3a) / (R3b-R3a) = − 3.11234
Conditional expression (4) f3 / fe = 4.119108
Conditional expression (5) Y0 / fe = 0.30823
Conditional expression (6) (−f2) /fe=0.86650
Conditional expression (7) f4 / (− f2) = 1.55465
Conditional expression (8) ΣD12 / fe = 0.51783
Conditional expression (9) D2 / fe = 0.09863

  8 (a), 8 (b) and 8 (c) respectively show the eyepiece according to the fourth example when the diopter is -1 [1 / m], -4 [1 / m], and FIG. 6 is a diagram showing various aberrations at +4 [1 / m]. From the respective aberration diagrams, it can be seen that the eyepiece according to the fourth example has excellent optical performance with various aberrations corrected well within the diopter adjustment range.

(5th Example)
The fifth embodiment will be described with reference to FIGS. 9 and 10 and Table 5. FIG. As shown in FIG. 9, the eyepiece according to the present example, in order from the observation object Ob side, is a first lens L1 that is a positive lens, and a second lens that is a negative meniscus lens having a convex surface facing the eye point EP side. L2, a third lens L3 that is a positive meniscus lens having a convex surface facing the eye point EP, and a fourth lens L4 that is a positive meniscus lens having a convex surface facing the eye point EP.

  In the eyepiece according to the present example, the lens surfaces on the observation object Ob side and the lens surfaces on the eye point EP side of all the first to fourth lenses L1 to L4 are aspherical lenses. In this eyepiece lens, diopter adjustment is performed by moving the first to fourth lenses L1 to L4 integrally along the optical axis.

  Table 5 below lists values of specifications of the optical system according to the fifth example.

(Table 5) Fifth Example [Overall specification]
Y0 = 5
TL = 22.95980

[Lens specifications]
Surface number RD nd νd
1) ∞ (variable) 1.0000
2) * 90.7521 4.7000 1.5439 55.9
3) * -7.8134 2.0000 1.0000
4) * -6.2792 1.6000 1.6425 22.47
5) * -22.9554 0.3000 1.0000
6) * -43.0195 3.0000 1.5439 55.9
7) * -20.0000 0.3000 1.0000
8) * -1216.2247 4.5000 1.5311 55.91
9) * -11.3542 (variable) 1.0000
EP

[Aspherical data]
κ A4 A6 A8 A10
2nd surface 1.0000 -1.31439E-04 1.54993E-06 -1.57988E-08 0.00000E + 00
3rd surface 0.2367 2.44623E-04 -7.17905E-06 1.29725E-07 -1.08282E-09
4th surface 0.2040 1.29284E-05 -8.91948E-06 1.80972E-07 -1.39480E-09
5th surface 2.5340 -5.54232E-05 2.61869E-07 7.73601E-09 -2.64719E-11
6th surface 1.0000 3.70622E-05 -4.02300E-07 -1.00000E-09 -5.00000E-11
7th surface 0.9225 -4.91899E-05 4.06470E-07 4.59359E-10 -8.87353E-11
8th surface 1.0000 3.26107E-05 7.45239E-08 -3.70471E-09 5.60699E-11
9th surface -1.2996 -4.29675E-05 3.50865E-07 -4.05773E-09 5.79402E-11

[Variable interval data]
Diopter -1 -4 +4
fe 16.70989 16.70989 16.70989
D1 6.55980 5.67390 7.91890
D9 23.00000 23.58187 21.90101

[Conditional expression values]
-F2 = 13.97744
f3 = 65.70050
f4 = 21.55216
fe = 16.70989
D2 = 1.60000
ΣD12 = 8.30000
Conditional expression (1) f4 / fe = 1.28978
Conditional expression (2) (R4b + R4a) / (R4b−R4a) = − 1.01885
Conditional expression (3) (R3b + R3a) / (R3b-R3a) = − 2.73766
Conditional expression (4) f3 / fe = 3.93183
Conditional expression (5) Y0 / fe = 0.29922
Conditional expression (6) (−f2) /fe=0.83648
Conditional expression (7) f4 / (− f2) = 1.54192
Conditional expression (8) ΣD12 / fe = 0.49671
Conditional expression (9) D2 / fe = 0.09575

  10 (a), 10 (b), and 10 (c) respectively show the eyepiece according to the fifth example when the diopter is -1 [1 / m], -4 [1 / m], and FIG. 6 is a diagram showing various aberrations at +4 [1 / m]. From the respective aberration diagrams, it can be seen that the eyepiece according to the fifth example has excellent optical performance with various aberrations corrected well within the diopter adjustment range.

(Sixth embodiment)
A sixth embodiment will be described with reference to FIGS. 11 and 12 and Table 6. FIG. As shown in FIG. 11, the eyepiece according to the present example, in order from the observation object Ob side, is a first lens L1 that is a positive lens, and a second lens that is a negative meniscus lens having a convex surface facing the eye point EP side. L2, a third lens L3 that is a positive meniscus lens having a convex surface facing the eye point EP, and a fourth lens L4 that is a positive meniscus lens having a convex surface facing the eye point EP.

  In the eyepiece according to the present example, the lens surfaces on the observation object Ob side and the lens surfaces on the eye point EP side of all the first to fourth lenses L1 to L4 are aspherical lenses. In this eyepiece lens, diopter adjustment is performed by moving the first to fourth lenses L1 to L4 integrally along the optical axis.

  Table 6 below provides values of specifications of the optical system according to the sixth example.

(Table 6) Sixth Example [Overall specification]
Y0 = 5
TL = 22.86070
[Lens specifications]
Surface number RD nd νd
1) ∞ (variable) 1.0000
2) * 88.0367 4.7000 1.5439 55.9
3) * -8.1291 1.9500 1.0000
4) * -6.2866 1.6000 1.6425 22.47
5) * -26.0324 0.3000 1.0000
6) * -126.8462 3.3000 1.5311 55.91
7) *-19.1573 0.3000 1.0000
8) * -231.7503 4.1000 1.5311 55.91
9) * -11.7234 (variable) 1.0000
EP

[Aspherical data]
κ A4 A6 A8 A10
2nd surface 1.0000 -8.78463E-05 -3.51490E-06 -9.41403E-09 0.00000E + 00
3rd surface 0.1916 1.86349E-04 -1.13314E-05 1.82562E-07 -1.61658E-09
4th surface 0.1939 -4.74973E-05 -1.07142E-05 2.44188E-07 -1.87401E-09
Fifth surface 2.4965 -7.85180E-05 1.29556E-07 4.93542E-09 -1.96957E-11
6th surface 54.5488 -2.28563E-06 -3.07886E-07 -1.00000E-09 -5.00000E-11
7th surface 1.1838 -5.16769E-05 2.89593E-07 8.73810E-10 -8.13180E-11
8th surface 1.0000 2.21932E-05 4.12601E-08 -3.71817E-09 7.03478E-11
9th surface -1.4472 -4.00499E-05 3.51401E-07 -2.80142E-09 5.42279E-11

[Variable interval data]
Diopter -1 -4 +4
fe 16.71395 16.71395 16.71395
D1 6.61070 5.72550 7.97140
D9 23.00000 23.58157 21.89997

[Conditional expression values]
-F2 = 13.32202
f3 = 42.04107
f4 = 23.10068
fe = 16.71395
D2 = 1.60000
ΣD12 = 8.25000
Conditional expression (1) f4 / fe = 1.38212
Conditional expression (2) (R4b + R4a) / (R4b-R4a) =-1.10656
Conditional expression (3) (R3b + R3a) / (R3b-R3a) =-1.35579
Conditional expression (4) f3 / fe = 2.51533
Conditional expression (5) Y0 / fe = 0.29915
Conditional expression (6) (−f2) /fe=0.79706
Conditional expression (7) f4 / (− f2) = 1.73402
Conditional expression (8) ΣD12 / fe = 0.49360
Conditional expression (9) D2 / fe = 0.09573

  FIGS. 12 (a), 12 (b) and 12 (c) respectively show the eyepiece according to the sixth example when the diopter is -1 [1 / m], -4 [1 / m], and FIG. 6 is a diagram showing various aberrations at +4 [1 / m]. From each aberration diagram, it can be seen that the eyepiece according to Example 6 has excellent optical performance with various aberrations corrected well within the diopter adjustment range.

(Seventh embodiment)
The seventh embodiment will be described with reference to FIGS. 13 and 14 and Table 7. FIG. As shown in FIG. 13, the eyepiece according to the present example has a first lens L1 that is a positive meniscus lens having a convex surface facing the eye point EP and a convex surface facing the eye point EP in order from the observation object Ob side. A second lens L2 that is a negative meniscus lens directed toward, a third lens L3 that is a positive meniscus lens having a convex surface directed toward the eye point EP, and a fourth lens that is a positive meniscus lens directed toward the eye point EP. L4.

  In the eyepiece according to the present example, the lens surfaces on the observation object Ob side and the lens surfaces on the eye point EP side of all the first to fourth lenses L1 to L4 are aspherical lenses. In this eyepiece lens, diopter adjustment is performed by moving the first to fourth lenses L1 to L4 integrally along the optical axis.

  Table 7 below provides values of specifications of the optical system according to the seventh example.

(Table 7) Seventh Example [Overall specification]
Y0 = 5
TL = 22.97000

[Lens specifications]
Surface number RD nd νd
1) ∞ (variable) 1.0000
2) * -1000.0000 4.6000 1.5311 55.91
3) * -6.7632 1.9500 1.0000
4) * -5.8927 1.6000 1.6349 23.96
5) * -27.9860 0.4000 1.0000
6) * -167.7913 4.0000 1.5311 55.91
7) *-14.4276 0.3000 1.0000
8) * -73.2393 3.5000 1.5311 55.91
9) * -13.2128 (variable) 1.0000
EP

[Aspherical data]
κ A4 A6 A8 A10
2nd surface 1.3442 -1.07830E-04 3.90090E-07 -8.84450E-09 -6.05531E-11
3rd surface -0.5510 1.18864E-04 -7.09448E-06 9.93632E-08 -8.93501E-10
4th surface -0.0517 7.31009E-05 -1.13896E-05 1.67308E-07 -1.44549E-09
5th surface 9.2441 -1.64571E-05 1.25145E-06 5.45983E-09 -3.19170E-12
6th surface -50.0000 8.89386E-05 -3.82715E-07 8.06580E-09 -1.05880E-10
7th surface 1.1542 -4.64168E-05 5.44070E-07 9.86855E-09 -1.20551E-10
8th surface -10.0000 8.66618E-06 3.43166E-07 -9.23807E-10 1.08233E-10
9th surface -1.3559 3.19815E-05 -5.38622E-08 -4.50667E-09 1.67511E-10

[Variable interval data]
Diopter -1 -4 +4
fe 16.71382 16.71382 16.71382
D1 6.62000 5.73360 7.98200
D9 23.00000 23.88233 21.63453

[Conditional expression values]
-F2 = 12.09635
f3 = 29.45461
f4 = 29.75240
fe = 16.71382
D2 = 1.60000
ΣD12 = 8.15000
Conditional expression (1) f4 / fe = 1.78011
Conditional expression (2) (R4b + R4a) / (R4b-R4a) =-1.44023
Conditional expression (3) (R3b + R3a) / (R3b-R3a) =-1.18815
Conditional expression (4) f3 / fe = 1.76229
Conditional expression (5) Y0 / fe = 0.29915
Conditional expression (6) (-f2) /fe=0.72373
Conditional expression (7) f4 / (− f2) = 2.45962
Conditional expression (8) ΣD12 / fe = 0.48762
Conditional expression (9) D2 / fe = 0.09573

14 (a), 14 (b), and 14 (c) respectively show the eyepiece according to the seventh example when the diopter is -1 [1 / m], -4 [1 / m], and FIG. 6 is a diagram showing various aberrations at +4 [1 / m]. From each aberration diagram, it can be seen that the eyepiece according to the seventh example has excellent optical performance with various aberrations corrected well within the diopter adjustment range.

(Eighth embodiment)
The eighth embodiment will be described with reference to FIGS. 15 and 16 and Table 8. FIG. As shown in FIG. 15, the eyepiece according to the present example has a first lens L1 that is a positive meniscus lens having a convex surface directed toward the eye point EP and a convex surface toward the eye point EP in order from the observation object Ob side. A second lens L2 that is a negative meniscus lens directed toward, a third lens L3 that is a positive meniscus lens having a convex surface directed toward the eye point EP, and a fourth lens that is a positive meniscus lens directed toward the eye point EP. L4.

  In the eyepiece according to the present example, the lens surfaces on the observation object Ob side and the lens surfaces on the eye point EP side of all the first to fourth lenses L1 to L4 are aspherical lenses. In this eyepiece lens, diopter adjustment is performed by moving the first to fourth lenses L1 to L4 integrally along the optical axis.

  Table 8 below provides values of specifications of the optical system according to the eighth example.

(Table 8) Eighth Example [Overall Specifications]
Y0 = 5
TL = 22.36316

[Lens specifications]
Surface number RD nd νd
1) ∞ (variable) 1.0000
2) * -1000.0000 4.3000 1.5311 55.91
3) * -6.5303 1.6810 1.0000
4) * -5.6162 1.6000 1.6349 23.96
5) * -25.2056 0.4000 1.0000
6) * -85.9315 4.2000 1.5311 55.91
7) *-13.2626 0.3000 1.0000
8) * -60.0000 2.8000 1.5311 55.91
9) *-13.4414 (variable) 1.0000
EP

[Aspherical data]
κ A4 A6 A8 A10
2nd surface 1.3442 -1.03947E-04 1.99797E-07 -8.84450E-09 2.49435E-10
3rd surface -0.6793 9.59735E-05 -5.32187E-06 5.51814E-08 -4.31015E-10
4th surface 0.0276 2.10923E-04 -9.95184E-06 5.18624E-08 -3.32847E-10
5th surface 5.0000 -8.56728E-06 1.02735E-06 6.33926E-10 -3.19170E-12
6th surface -5.0000 8.58318E-05 -2.89454E-07 8.06580E-09 -1.05880E-10
7th surface 1.6785 -1.01457E-05 4.00765E-07 1.20705E-08 -5.41393E-11
8th surface -5.0000 -8.83448E-06 3.82173E-07 -1.00000E-10 8.76418E-11
9th surface -1.1611 3.57114E-05 -5.94639E-09 -5.07206E-09 1.47617E-10

[Variable interval data]
Diopter -1 -3 +3
fe 16.72439 16.72439 16.72439
d1 7.08220 6.49980 8.18360
d2 23.00000 23.58064 21.89711

[Conditional expression values]
-F2 = 11.75386
f3 = 28.94925
f4 = 31.94863
fe = 16.72439
D2 = 1.60000
ΣD12 = 7.58100
Conditional expression (1) f4 / fe = 1.91030
Conditional expression (2) (R4b + R4a) / (R4b-R4a) =-1.57740
Conditional expression (3) (R3b + R3a) / (R3b−R3a) = − 1.36501
Conditional expression (4) f3 / fe = 1.73096
Conditional expression (5) Y0 / fe = 0.29896
Conditional expression (6) (−f2) /fe=0.70280
Conditional expression (7) f4 / (− f2) = 2.71814
Conditional expression (8) ΣD12 / fe = 0.45329
Conditional expression (9) D2 / fe = 0.09567

  16 (a), 16 (b) and 16 (c) respectively show the eyepiece according to the eighth example when the diopter is -1 [1 / m], -3 [1 / m], and FIG. 5 is a diagram showing various aberrations at +3 [1 / m]. From the respective aberration diagrams, it can be seen that the eyepiece according to the eighth example has excellent optical performance with various aberrations corrected well within the diopter adjustment range.

(Ninth embodiment)
The ninth embodiment will be described with reference to FIGS. 17 and 18 and Table 9. FIG. As shown in FIG. 17, the eyepiece according to the present example has a first lens L1 that is a positive meniscus lens having a convex surface facing the eye point EP and a convex surface facing the eye point EP in order from the observation object Ob side. A second lens L2 that is a negative meniscus lens directed toward, a third lens L3 that is a positive meniscus lens having a convex surface directed toward the eye point EP, and a fourth lens that is a positive meniscus lens directed toward the eye point EP. L4.

  In the eyepiece according to the present example, the lens surfaces on the observation object Ob side and the lens surfaces on the eye point EP side of all the first to fourth lenses L1 to L4 are aspherical lenses. In this eyepiece lens, diopter adjustment is performed by moving the first to fourth lenses L1 to L4 integrally along the optical axis.

  Table 9 below provides values of specifications of the optical system according to the ninth example.

(Table 9) Ninth Example [Overall Specifications]
Y0 = 5
TL = 22.98810

[Lens specifications]
Surface number RD nd νd
1) ∞ (variable) 1.0000
2) * -800.0000 4.4000 1.5311 55.91
3) * -6.0413 1.7000 1.0000
4) * -5.9440 1.6000 1.6349 23.96
5) * -29.7733 0.4000 1.0000
6) * -58.4875 4.0000 1.5311 55.91
7) * -16.0000 0.3000 1.0000
8) * -50.0000 3.5000 1.5311 55.91
9) * -11.9000 (variable) 1.0000
EP

[Aspherical data]
κ A4 A6 A8 A10
2nd surface 1.3442 -1.07830E-04 3.90090E-07 -8.84450E-09 2.76999E-10
3rd surface -1.4233 -1.19262E-04 -3.26981E-06 4.82976E-08 -2.35381E-10
4th surface -1.4931 -3.74916E-04 -7.14648E-06 1.12503E-07 -1.09459E-09
5th surface 10.5775 2.97922E-06 9.82438E-07 9.81572E-09 -3.19170E-12
6th surface -5.0000 1.23107E-04 -2.49720E-07 8.06580E-09 -1.05880E-10
7th surface 1.6143 -6.62136E-05 2.73100E-07 9.92362E-09 -9.42978E-11
8th surface -5.0000 -1.69714E-05 6.45037E-07 -8.00000E-09 1.38820E-10
9th surface -0.6385 3.90253E-05 -2.75111E-09 -8.81598E-09 1.75243E-10

[Variable interval data]
Diopter -1 -3 +3
fe 16.71198 16.71198 16.71198
d1 7.08810 6.50440 8.18580
d2 23.00000 23.58153 21.90032

[Conditional expression values]
-F2 = 12.00991
f3 = 40.15961
f4 = 28.49658
fe = 16.71198
D2 = 1.60000
ΣD12 = 7.70000
Conditional expression (1) f4 / fe = 1.70516
Conditional expression (2) (R4b + R4a) / (R4b−R4a) = − 1.62467
Conditional expression (3) (R3b + R3a) / (R3b-R3a) =-1.75316
Conditional expression (4) f3 / fe = 2.40304
Conditional expression (5) Y0 / fe = 0.29919
Conditional expression (6) (-f2) / fe = 0.71864
Conditional expression (7) f4 / (− f2) = 2.37276
Conditional expression (8) ΣD12 / fe = 0.46075
Conditional expression (9) D2 / fe = 0.09574

  FIGS. 18 (a), 18 (b) and 18 (c) respectively show the eyepiece according to the ninth example when the diopter is -1 [1 / m], -3 [1 / m], and FIG. 5 is a diagram showing various aberrations at +3 [1 / m]. From each aberration diagram, it can be seen that the eyepiece according to the ninth example has excellent optical performance with various aberrations corrected well within the diopter adjustment range.

Here, each said Example has shown one specific example of this invention, and this invention is not limited to these. For example, the following contents can be appropriately adopted within a range that does not impair the optical performance of the eyepiece of the present embodiment.

  Although a four-lens configuration is shown as a numerical example of the eyepiece lens of the present embodiment, the present invention can also be applied to other lens configurations such as five. Further, a configuration in which a lens is added to the most observation object side or a configuration in which a lens is added to the most eyepoint side may be used.

  The lens surface of the lens constituting the eyepiece of this embodiment may be a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, it is preferable because lens processing and assembly adjustment are easy, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented. Even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is aspherical, any of aspherical surface by grinding, glass mold aspherical surface in which glass is molded into an aspherical shape, or composite aspherical surface in which resin provided on the glass surface is formed in an aspherical shape Good. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  In order to reduce flare and ghost and achieve high optical performance with high contrast, an antireflection film having high transmittance in a wide wavelength range is applied to the lens surface of the lens constituting the eyepiece of this embodiment. Also good.

  The eyepiece of this embodiment has a configuration in which the first to fourth lenses L1 to L4 are integrated or the whole eyepiece is moved to adjust diopter, but the most eyepoint side lens is fixed. The entire lens closer to the observation object than the lens may be moved integrally, or at least some of the first to fourth lenses L1 to L4 may be moved.

L1 1st lens L2 2nd lens L3 3rd lens L4 4th lens
Op Observation object EP Eye point 1 Camera OL Objective lens C Image sensor EVF Electronic viewfinder EL Eyepiece optical system

Claims (16)

A first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a fourth lens having a positive refractive power, which are arranged in order from the observation object side. And
An eyepiece that satisfies the following conditional expression:
0.80 <f4 / fe <2.20
Where f4: focal length of the fourth lens,
fe: Focal length when the eyepiece diopter is -1 [1 / m]. The eyepiece according to claim 1, wherein the following conditional expression is satisfied.
-1.73 <(R4b + R4a) / (R4b-R4a) <-0.35
Where R4b: radius of curvature of the fourth lens on the eye point side,
R4a: radius of curvature of the fourth lens on the observation object side. The eyepiece according to claim 1, wherein the following conditional expression is satisfied.
−4.00 <(R3b + R3a) / (R3b−R3a) <− 0.95
Where R3b: radius of curvature of the third lens on the eye point side,
R3a: radius of curvature of the third lens on the observation object side. The eyepiece according to claim 1, wherein the following conditional expression is satisfied.
1.40 <f3 / fe <4.80
Where f3: focal length of the third lens,
fe: Focal length when the eyepiece diopter is -1 [1 / m]. The eyepiece according to claim 1, wherein the following conditional expression is satisfied.
0.22 <Y0 / fe <0.40
Y0: height of the observation object.
fe: Focal length when the eyepiece diopter is -1 [1 / m]. The eyepiece according to claim 1, wherein the following conditional expression is satisfied.
0.45 <(− f2) / fe <1.10
Where f2: focal length of the second lens,
fe: Focal length when the eyepiece diopter is -1 [1 / m]. The eyepiece according to claim 1, wherein the following conditional expression is satisfied.
1.20 <f4 / (− f2) <2.80
Where f2: focal length of the second lens,
f4: focal length of the fourth lens. The eyepiece according to claim 1, wherein the following conditional expression is satisfied.
0.40 <ΣD12 / fe <0.60
However, ΣD12: distance on the optical axis from the lens surface on the observation object side of the first lens to the lens surface on the eye point side of the second lens
fe: Focal length when the eyepiece diopter is -1 [1 / m]. The eyepiece according to claim 1, wherein the following conditional expression is satisfied.
0.05 <D2 / fe <0.20
Where D2: the thickness of the second lens on the optical axis,
fe: Focal length when the eyepiece diopter is -1 [1 / m].   The eyepiece according to claim 1, wherein at least one surface of the first lens is an aspherical surface.   The eyepiece according to claim 1, wherein all of the first to fourth lenses constituting the eyepiece have at least one aspheric surface.   The eyepiece according to claim 1, wherein at least one of the first to fourth lenses is a plastic lens.   The diopter adjustment is performed by moving the first lens, the second lens, the third lens, and the fourth lens along an optical axis. Eyepiece.   The eyepiece lens according to any one of claims 1 to 13, wherein the diopter adjustment is performed by integrally moving all the lenses constituting the eyepiece lens.   An optical apparatus configured by mounting the eyepiece lens according to claim 1. A method of manufacturing an eyepiece for observing an observation object,
A first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a positive refractive power, in which the eyepiece lenses are arranged in order from the observation object side. And a fourth lens having
A method for manufacturing an eyepiece characterized by being configured to satisfy the following conditional expression:
0.80 <f4 / fe <2.20
Where f4: focal length of the fourth lens,
fe: Focal length when the eyepiece diopter is -1 [1 / m].

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