JP6750081B2 - Eyepiece and imaging device - Google Patents

Description

The present invention relates to an eyepiece lens and an image pickup apparatus, and more particularly to an eyepiece lens suitable for magnifying observation of an image displayed on an image display element, and an image pickup apparatus equipped with this eyepiece lens.

2. Description of the Related Art Conventionally, in a viewfinder of an image pickup device such as a digital camera, an eyepiece lens for enlarging an image displayed on an image display device such as a liquid crystal display device and observing it with the naked eye is used. Such an eyepiece is required to have a small size and high image forming performance. In order to meet this demand, Patent Document 1 below proposes an eyepiece lens having a four-element structure in which a positive lens, a negative lens, a positive lens, and a positive lens are arranged in order from the observation object side. Further, as an eyepiece lens having a similar four-lens structure, one described in Patent Document 2 below is known.

JP, 2016-001209, A JP, 2005-075713, A

In order to make the viewfinder easy to observe, it is desired that the distance from the eyepiece to the position of the observer's pupil is long, that is, the so-called high eye point. It is also required that the eyepiece has a wide field of view. However, it was not easy to expand the field of view with the high eye point. The eyepiece described in Patent Document 1 is desired to further expand the apparent field of view. The eyepiece lens described in Patent Document 2 is desired to have a higher eye point.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an eyepiece having a wide apparent field of view and a good optical performance even at a high eye point, and an imaging device including the eyepiece. It is a thing.

A first eyepiece lens of the present invention comprises, in order from an observation object side to an eyepoint side, a first lens group having a positive refractive power, a second lens group having a positive or negative refractive power, and a positive refractive power. And a third lens group having, and a first lens group including one lens having a positive refractive power with a convex surface facing the eyepoint side, and a second lens group including three or less lenses. A meniscus lens having a negative refractive power with a convex surface facing the eyepoint side is disposed on the most object side of the second lens group, and includes at least one negative lens and at least one positive lens. The lens group is composed of one lens having a positive refractive power with the convex surface facing the eyepoint side, and is characterized by satisfying the following conditional expression (1-a).
0.8<f/TL≦0.962 (1-a)
However,
f: Focal length of entire system TL: Distance on the optical axis from the observation object side surface of the lens of the first lens group to the eye point side surface of the lens of the third lens group.

The second eyepiece lens of the present invention comprises, in order from the observation object side to the eyepoint side, a first lens group having a positive refractive power, a second lens group having a positive or negative refractive power, and a positive refractive power. And a third lens group having, and a first lens group including one lens having a positive refractive power with a convex surface facing the eyepoint side, and a second lens group including three or less lenses. , And at least one negative lens and at least one positive lens, and the third lens group is composed of one meniscus lens having a positive refracting power with a convex surface facing the eyepoint side. -A) and (4) are satisfied.
0.8<f/TL≦0.962 (1-a)
0.01<(R3f-R3r)/(R3f+R3r)<0.3 (4)
However,
f: focal length of the entire system TL: distance on the optical axis from the observation object side surface of the lens of the first lens group to the eyepoint side surface of the meniscus lens of the third lens group R3f: meniscus of the third lens group Paraxial radius of curvature R3r of the observation object side surface of the lens: a paraxial curvature radius of the eyepoint side surface of the meniscus lens of the third lens group.

The third eyepiece lens of the present invention comprises, in order from the observation object side to the eyepoint side, a first lens group having a positive refractive power, a second lens group having a positive or negative refractive power, and a positive refractive power. And a third lens group having, and a first lens group including one lens having a positive refractive power with a convex surface facing the eyepoint side, and a second lens group including three or less lenses. , At least one negative lens and at least one positive lens, and the third lens group is composed of one lens having a positive refractive power with the convex surface facing the eyepoint side, and the following conditional expression (1- a) and (6-a) are satisfied.
0.8<f/TL≦0.962 (1-a)
0.10883≦Nmax−Nmin<0.3 (6-a)
However,
f: focal length of the entire system TL: distance on the optical axis from the observation object side surface of the lens of the first lens group to the eyepoint side surface of the lens of the third lens group Nmax: d line of the lens of the entire system Maximum value Nmin of the refractive index at: The minimum value of the refractive index at the d-line of the lens of the entire system.

An image pickup apparatus of the present invention includes the eyepiece lens of the present invention.

Note that the above-mentioned "consisting of" means a substantial thing, and in addition to those listed as the constituent elements, a lens, a diaphragm, a cover glass, a filter, or the like having substantially no power is used. Optical elements other than lenses, lens flanges, and/or lens barrels, etc. may be included.

The “lens group” described above is not limited to one including a plurality of lenses and one including only one lens. The above "having positive refractive power-lens group" means that the entire lens group has positive refractive power. The same applies to the above-mentioned "having negative refractive power-lens group". Regarding the sign of the refracting power of the lens group, the sign of the refracting power of the lens, and the shape of the lens, those including an aspherical surface are considered in the paraxial region. The sign of the paraxial radius of curvature is positive when the surface shape with the convex surface facing the object side is positive, and negative when the surface shape with the convex surface facing the eyepoint side is negative.

The number of lenses described above is the number of constituent lenses. For example, the number of lenses in a cemented lens in which a plurality of single lenses made of different materials are cemented is the number of single lenses constituting this cemented lens. Will be expressed as. However, a compound aspherical lens (a lens in which a spherical lens and an aspherical film formed on the spherical lens are integrally configured to function as one aspherical lens as a whole) is a cemented lens. Is not considered and is treated as one lens. Further, all the above conditional expressions are based on the d-line (wavelength 587.6 nm).

According to the present invention, in the lens system of the three-group configuration of positive positive positive or positive negative negative in order from the observation object side, the configuration of each lens group is suitably set in detail so as to satisfy the predetermined conditional expression. Therefore, it is possible to provide an eyepiece having a wide apparent field of view and a good optical performance even at a high eye point, and an imaging device including the eyepiece.

It is sectional drawing which shows the structure and optical path of the eyepiece of Example 1 of this invention. It is sectional drawing which shows the structure and optical path of the eyepiece of Example 2 of this invention. It is sectional drawing which shows the structure and optical path of the eyepiece of Example 3 of this invention. FIG. 3 is a diagram of aberrations of the eyepiece lens of Example 1 of the invention. FIG. 8 is a diagram of aberrations of the eyepiece lens of Example 2 of the invention. It is each aberration figure of the eyepiece of Example 3 of this invention. It is a perspective view of the back side of the imaging device concerning one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing the configuration of an eyepiece lens according to an embodiment of the present invention, which corresponds to Example 1 described later. Similarly, sectional views of configuration examples corresponding to the eyepieces of Examples 2 and 3 described later are shown in FIGS. 2 and 3, respectively. 1 to 3 have the same drawing method and the same basic configuration, the following description will be given mainly with reference to FIG.

In the example shown in FIG. 1, the image display element 1 is used as an observation object, and a point on the optical axis on the image display element 1 and a light flux traveling from the highest point to the eye point EP are also shown. The eye point EP shown in FIG. 1 does not indicate the size or shape, but indicates the position in the optical axis direction. In FIG. 1, the left side is shown as the observation object side, and the right side is shown as the eyepoint side. In the following description, the observation object side is also referred to as the object side.

The eyepiece lens 3 can be used when enlarging and observing an image displayed on the image display surface of the image display element 1. Examples of the image display element 1 include a liquid crystal display element and the like. FIG. 1 shows an example in which parallel plate optical members 2 and 4 are arranged between the image display element 1 and the eyepiece lens 3 and between the eyepiece lens 3 and the eyepoint EP, respectively. The optical members 2 and 4 are assumed to be protective cover glasses, various filters, and the like, and the present invention can be configured without them.

The eyepiece 3 includes a first lens group G1 having a positive refractive power and a second lens group G2 having a positive or negative refractive power, which are arranged in order from the object side to the eyepoint side along the optical axis Z. And a third lens group G3 having a positive refractive power.

The first lens group G1 is composed of one meniscus lens having a positive refractive power with a convex surface facing the eyepoint side. The meniscus shape of this lens is advantageous for correcting distortion. Further, by forming this lens into a meniscus shape, it is advantageous to shorten the distance on the optical axis (hereinafter referred to as the total length) from the image display surface of the image display element 1 to the lens surface of the eyepiece 3 on the most eyepoint side. , It can also contribute to the high eye point.

The first lens group G1 preferably has at least one aspherical surface. By making at least one surface an aspherical surface, it is possible to easily correct high-order astigmatism, spherical aberration, and distortion.

The second lens group G2 is composed of three or less lenses, and is configured to include at least one negative lens and at least one positive lens. By using a small number of lenses, the effect of shortening the total length can be obtained. In addition, chromatic aberration can be corrected by using a configuration including a positive lens and a negative lens.

The third lens group G3 is composed of one meniscus lens having a positive refractive power with a convex surface facing the eyepoint side. By making this lens a meniscus shape, it is possible to suppress the occurrence of spherical aberration.

The third lens group G3 preferably has at least one aspherical surface. By making at least one surface an aspherical surface, it is possible to easily correct high-order astigmatism, spherical aberration, and distortion.

In the example shown in FIG. 1, the first lens group G1 includes a lens L11, the second lens group G2 includes three lenses L21 to L23 in order from the object side, and the third lens group G3 includes a lens L31. .. By configuring the second lens group G2 to include three lenses, the absolute value of the radius of curvature of each lens can be increased and spherical aberration can be reduced. The second lens group G2 may be composed of two lenses as in the example shown in FIG. 2, and in this case, the length of the eyepiece lens 3 in the optical axis direction, that is, It is possible to shorten the length in the optical axis direction from the lens surface of the eyepiece 3 closest to the object side to the lens surface closest to the eyepoint side.

The eyepiece lens 3 is configured to satisfy the following conditional expression (1).
0.8<f/TL<1.1 (1)
However,
f: focal length of the entire system TL: distance on the optical axis from the observation object side surface of the meniscus lens of the first lens group to the eyepoint side surface of the meniscus lens of the third lens group

TL of the conditional expression (1) is the length of the above-mentioned eyepiece lens 3 in the optical axis direction. If the lower limit of conditional expression (1) is not exceeded, it becomes easier to secure the distance from the eyepiece 3 to the image display element 1 and the space for adjusting the diopter. If the upper limit of conditional expression (1) is not exceeded, a distance for bending the principal ray of the off-axis light beam can be secured, which is advantageous for achieving a high eyepoint.

In order to enhance the effect of conditional expression (1), it is preferable to satisfy the following conditional expression (1-1).
0.9<f/TL<1 (1-1)

Further, it is preferable that the eyepiece lens 3 satisfies the following conditional expression (2).
0.78<TGL/TL<0.97 (2)
However,
TGL: Sum of center thicknesses of lenses of all systems TL: Distance on the optical axis from the observation object side surface of the meniscus lens of the first lens group to the eyepoint side surface of the meniscus lens of the third lens group

By not falling below the lower limit of the conditional expression (2), it is possible to reduce the air gap between the lenses and suppress the occurrence of high-order astigmatism, which is a problem in a wide angle of view. If the upper limit of conditional expression (2) is not exceeded, low-order astigmatism can be easily corrected.

In order to enhance the effect of conditional expression (2), it is more preferable to satisfy the following conditional expression (2-1).
0.8<TGL/TL<0.95 (2-1)

Further, it is preferable that the eyepiece lens 3 satisfies the following conditional expression (3).
0.65<(R1f-R1r)/(R1f+R1r)<1 (3)
However,
R1f: Paraxial radius of curvature of the observation object side surface of the meniscus lens of the first lens group R1r: Paraxial radius of curvature of the eyepoint side surface of the meniscus lens of the first lens group

Conditional expression (3) defines the shape factor of the meniscus lens of the first lens group G1. It is advantageous for the correction of astigmatism if the lower limit of conditional expression (3) is not exceeded. If the upper limit of conditional expression (3) is not exceeded, it is advantageous for shortening the overall length and achieving a high eye point.

In order to enhance the effect of conditional expression (3), it is more preferable to satisfy the following conditional expression (3-1).
0.7<(R1f-R1r)/(R1f+R1r)<0.95 (3-1)

Further, it is preferable that the eyepiece lens 3 satisfies the following conditional expression (4).
0.01<(R3f-R3r)/(R3f+R3r)<0.3 (4)
However,
R3f: Paraxial radius of curvature of the observation object side surface of the meniscus lens of the third lens group R3r: Paraxial radius of curvature of the eyepoint side surface of the meniscus lens of the third lens group

Conditional expression (4) defines the shape factor of the meniscus lens of the third lens group G3. If the value is not less than or equal to the lower limit of the conditional expression (4), it is advantageous for correction of astigmatism, and generation of spherical aberration can be suppressed. If the upper limit of conditional expression (4) is not exceeded, it is advantageous for shortening the overall length and achieving a high eye point.

In order to enhance the effect of conditional expression (4), it is more preferable to satisfy the following conditional expression (4-1).
0.05<(R3f-R3r)/(R3f+R3r)<0.25 (4-1)

Further, it is preferable that the eyepiece lens 3 satisfies the following conditional expression (5).
1.75<Npave<2 (5)
Npave: Average value of refractive index at d line of the positive lens of the entire system

By preventing the average value of the refractive index of the positive lens included in the eyepiece lens 3 from falling below the lower limit of the conditional expression (5), the Petzval sum can be set to a suitable value and the curvature of field can be suppressed. If the upper limit of conditional expression (5) is not exceeded, a material having an appropriate Abbe number can be selected and chromatic aberration can be easily corrected.

In order to enhance the effect of conditional expression (5), it is more preferable to satisfy the following conditional expression (5-1).
1.8<Npave<1.95 (5-1)

Further, it is preferable that the eyepiece lens 3 satisfies the following conditional expression (6).
0.01<Nmax-Nmin<0.35 (6)
Nmax: maximum value of refractive index of d-line of lenses of all systems Nmin: minimum value of refractive index of d-lines of lenses of all systems

By preventing the refractive index difference of all lenses including the positive lens and the negative lens of the eyepiece lens 3 from falling below the lower limit of the conditional expression (6), it is possible to select a material having an appropriate Abbe number and correct chromatic aberration. It will be easy. If the upper limit of conditional expression (6) is not exceeded, it will be advantageous to make the lens system thinner.

In order to enhance the effect of conditional expression (6), it is more preferable to satisfy the following conditional expression (6-1).
0.05<Nmax-Nmin<0.3 (6-1)

The preferred configurations and possible configurations described above can be combined in any desired manner, and are preferably selectively used in accordance with required specifications. According to this embodiment, it is possible to realize an eyepiece lens having a wide apparent field of view and a good optical performance even at a high eye point. The "high eye point" here is the distance on the optical axis from the lens surface closest to the eye point in the air conversion distance to the eye point EP (hereinafter referred to as eye relief) when the diopter is -1 diopter. Is longer than 21 mm. Further, “wide apparent field of view” means that the apparent field of view is larger than 40°.

Next, numerical examples of the eyepiece of the present invention will be described.
[Example 1]
The lens configuration and optical path of the eyepiece of Example 1 are as shown in FIG. 1, and the illustration method and configuration are as described above as the example shown in FIG. The eyepiece of Example 1 has, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. It consists of and. The second lens group G2 includes, in order from the object side, a meniscus-shaped lens L21 having a negative refractive power with a convex surface facing the eyepoint side, and two lenses having a positive refractive power having a convex surface facing the eyepoint side. It is composed of meniscus lenses L22 and L23.

Table 1 shows basic lens data of the eyepiece of Example 1, Table 2 shows specifications, and Table 3 shows aspherical coefficients. Table 1 also includes the image display element 1 and the optical members 2 and 4. In the Si column of Table 1, the surface on the object side of the image display device 1 is the first, and the i-th surface (i= 0, 1, 2, 3,...), the radius of curvature of the i-th surface is shown in the Ri column, and the optical axis Z between the i-th surface and the i+1-th surface is shown in the Di column. The upper surface spacing is shown. In the column of Ndj in Table 1, the component on the most object side is the first component, and the d-line (wavelength 587. 6 nm), and the column of νdj shows the Abbe number for the d-line of the j-th constituent element from the object side.

The sign of the radius of curvature is positive when the surface shape with the convex surface facing the object side is positive, and negative when the surface shape with the convex surface facing the eyepoint side is negative. In Table 1, the surface number column of the surface corresponding to the eye point EP describes the surface number and the word (EP).

Table 2 shows the focal length f of the entire system, the apparent field of view 2ω, and the eye relief value at the air-equivalent distance based on the d-line. [°] in the column of 2ω means that the unit is degrees. The values shown in Table 2 are for a diopter of -1 diopter. The eyepiece of Example 1 can adjust the diopter in the range of −4 diopter to +2 diopter by integrally moving the entire lens system in the optical axis direction.

In Table 1, the surface number of the aspherical surface is marked with *, and the numerical value of the paraxial radius of curvature is described in the column of the radius of curvature of the aspherical surface. Table 3 shows the aspherical surface coefficient of each aspherical surface of the first embodiment. The numerical value “E±n” (n: integer) of the aspherical surface coefficient in Table 3 means “×10 ^±n ”. The aspherical surface coefficient is a value of each coefficient KA, Am (m=3, 4, 5,...) In the aspherical surface expression represented by the following expression.

However,
Zd: depth of the aspherical surface (length of a perpendicular line drawn from a point on the aspherical surface having a height h to a plane perpendicular to the optical axis where the aspherical surface abuts)
h: Height (distance from the optical axis to the lens surface)
C: paraxial curvature KA, Am: aspherical coefficient

In the data of each table, the unit of angle is degrees, and the unit of length is mm. In addition, in each of the tables shown below, numerical values rounded to a predetermined digit are described.

FIG. 4 shows aberration diagrams of the eyepiece lens of Example 1. In FIG. 4, spherical aberration, astigmatism, distortion (distortion), and chromatic aberration of magnification (chromatic aberration of magnification) are shown in order from the left. In the spherical aberration diagram, the aberrations associated with the d line (wavelength 587.6 nm), the C line (wavelength 656.3 nm), and the F line (wavelength 486.1 nm) are indicated by a solid line, a long dashed line, and a short dashed line, respectively. In the astigmatism diagram, aberrations regarding the d-line in the sagittal direction and the tangential direction are indicated by a solid line and a short broken line, respectively. In the distortion diagram, the solid line shows the aberration for the d-line. In the lateral chromatic aberration diagram, the aberrations associated with the C line and the F line are indicated by a long broken line and a short broken line, respectively. The unit of the horizontal axis of the spherical aberration diagram and the astigmatism diagram is diopter. Φ in the spherical aberration diagram means the diameter of the eye point when the unit is mm, and ω in the other aberration diagrams means the half angle of the apparent field of view.

The symbols, meanings, and description methods of the respective data relating to the above-mentioned first embodiment are the same as those of the following embodiments unless otherwise specified, so that the duplicated description will be omitted below.

[Example 2]
The lens structure and optical path of the eyepiece of Example 2 are as shown in FIG. The eyepiece of Example 2 has, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power. It consists of and. The second lens group G2 includes, in order from the object side, a meniscus-shaped lens L21 having a negative refractive power with a convex surface facing the eyepoint side and a meniscus-shaped lens L21 having a positive refractive power with a convex surface facing the eyepoint side. And a lens L22.

Table 4 shows basic lens data of the eyepiece of Example 2, Table 5 shows specifications, Table 6 shows aspherical coefficients, and FIG. 5 shows aberration diagrams. The values shown in Table 5 are those when the diopter is −1 diopter, and the eyepiece of Example 2 adjusts the diopter in the range of −4 diopter to +2 diopter by integrally moving the entire lens system in the optical axis direction. Is possible.

[Example 3]
The lens configuration and optical path of the eyepiece of Example 3 are as shown in FIG. The eyepiece of Example 3 has, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power. It consists of and. The second lens group G2 includes, in order from the object side, a meniscus lens L21 having a negative refractive power with a convex surface facing the eyepoint side, a biconcave lens L22, and a biconvex lens L23. ..

Table 7 shows basic lens data of the eyepiece of Example 3, Table 8 shows specifications, Table 9 shows aspherical coefficients, and FIG. 6 shows aberration diagrams. The values shown in Table 8 are for a diopter of -1 diopter, and the eyepiece of Example 3 adjusts the diopter in the range of -4 diopter to +2 diopter by integrally moving the entire lens system in the optical axis direction. Is possible.

Table 10 shows corresponding values of the conditional expressions (1) to (6) of the eyepieces of Examples 1 to 3. The values shown in Table 10 are based on the d line.

As can be seen from the above data, the eyepieces of Examples 1 to 3 have an apparent field of view of 40° or more and are sufficiently wide while having an eye relief of 24 mm or more and a high eye point when the diopter is -1 diopter. And various aberrations are well corrected and high optical performance is realized.

Next, the image pickup apparatus according to the embodiment of the present invention will be described. FIG. 7 is a perspective view showing a schematic configuration on the back side of the camera 100 according to the embodiment of the image pickup apparatus of the present invention. The camera 100 includes a finder 101 on the top of a camera body 102. The finder 101 has an eyepiece lens according to the embodiment of the present invention. Further, the camera 100 includes an operation button 103 for making various settings on the rear surface of the camera body 102, a zoom lever 104 for performing zooming, and a monitor 106 for displaying images and various setting screens. A shutter button 105 is provided on the upper surface of the. In the camera 100, a subject image formed by an image pickup lens (not shown) provided on the front surface of the camera body 102 is formed on the image pickup surface of an image pickup element (not shown). The user looks into the finder 101 from the back side and observes the finder image of the subject. Although FIG. 7 shows an example of the finder built in the camera 100, the present invention can be applied to an external finder. The image pickup apparatus of the present invention is not limited to the example shown in FIG. 7, and the present invention can be applied to a video camera or the like, for example.

Although the present invention has been described above with reference to the exemplary embodiments and examples, the present invention is not limited to the above-described exemplary embodiments and examples, and various modifications can be made. For example, the radius of curvature, the surface distance, the refractive index, the Abbe number, and the aspherical surface coefficient of each lens are not limited to the values shown in each of the above-mentioned numerical examples, and can take other values.

1 image display element 2 and 4 optical member 3 eyepiece 100 camera 101 viewfinder 102 camera body 103 operation button 104 zoom lever 105 shutter button 106 monitor EP eyepoint G1 first lens group G2 second lens group G3 third lens group L11, L21 to L23, L31 lens Z optical axis

Claims (4)

In order from the observation object side to the eyepoint side, a first lens group having a positive refractive power, a second lens group having a positive or negative refractive power, and a third lens group having a positive refractive power,
The first lens group includes one lens having a positive refractive power with a convex surface facing the eyepoint side,
The second lens group includes three or less lenses, and includes at least one negative lens and at least one positive lens,
On the most object side of the second lens group, a meniscus lens having a negative refractive power with a convex surface facing the eyepoint side is arranged,
The third lens group includes one lens having a positive refractive power with a convex surface facing the eyepoint side,
An eyepiece lens satisfying the following conditional expression (1-a).
0.8<f/TL≦0.962 (1-a)
However,
f: focal length of the entire system TL: distance on the optical axis from the observation object side surface of the lens of the first lens group to the eye point side surface of the lens of the third lens group In order from the observation object side to the eyepoint side, a first lens group having a positive refractive power, a second lens group having a positive or negative refractive power, and a third lens group having a positive refractive power,
The first lens group includes one lens having a positive refractive power with a convex surface facing the eyepoint side,
The second lens group includes three or less lenses, and includes at least one negative lens and at least one positive lens,
The third lens group is composed of one meniscus lens having a positive refractive power with a convex surface facing the eyepoint side,
An eyepiece lens satisfying the following conditional expressions (1-a) and (4).
0.8<f/TL≦0.962 (1-a)
0.01<(R3f-R3r)/(R3f+R3r)<0.3 (4)
However,
f: focal length of the entire system TL: distance on the optical axis from the observation object side surface of the lens of the first lens group to the eyepoint side surface of the meniscus lens of the third lens group R3f: the first Paraxial radius of curvature R3r of the surface of the meniscus lens on the observation object side of the third lens group R3r: Paraxial radius of curvature of the eyepoint side surface of the meniscus lens on the third lens group In order from the observation object side to the eyepoint side, a first lens group having a positive refractive power, a second lens group having a positive or negative refractive power, and a third lens group having a positive refractive power,
The first lens group includes one lens having a positive refractive power with a convex surface facing the eyepoint side,
The second lens group includes three or less lenses, and includes at least one negative lens and at least one positive lens,
The third lens group includes one lens having a positive refractive power with a convex surface facing the eyepoint side,
An eyepiece lens satisfying the following conditional expressions (1-a) and (6-a).
0.8<f/TL≦0.962 (1-a)
0.10883≦Nmax-Nmin<0.3 (6-a)
However,
f: focal length of the entire system TL: distance on the optical axis from the surface of the first lens group on the observation object side of the lens to the surface of the third lens group on the eyepoint side of the lens Nmax: of the entire system Maximum value of refractive index Nmin of d-line of lens: minimum value of refractive index of d-line of lenses of the entire system An image pickup apparatus comprising the eyepiece lens according to claim 1.