JPS6113735B2 - - Google Patents
Info
- Publication number
- JPS6113735B2 JPS6113735B2 JP14912880A JP14912880A JPS6113735B2 JP S6113735 B2 JPS6113735 B2 JP S6113735B2 JP 14912880 A JP14912880 A JP 14912880A JP 14912880 A JP14912880 A JP 14912880A JP S6113735 B2 JPS6113735 B2 JP S6113735B2
- Authority
- JP
- Japan
- Prior art keywords
- lens
- lenses
- negative
- rear conversion
- focal length
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000006243 chemical reaction Methods 0.000 claims description 16
- 238000004026 adhesive bonding Methods 0.000 claims description 2
- 230000004075 alteration Effects 0.000 description 20
- 238000010586 diagram Methods 0.000 description 4
- 206010010071 Coma Diseases 0.000 description 2
- 201000009310 astigmatism Diseases 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- DEXFNLNNUZKHNO-UHFFFAOYSA-N 6-[3-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperidin-1-yl]-3-oxopropyl]-3H-1,3-benzoxazol-2-one Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C1CCN(CC1)C(CCC1=CC2=C(NC(O2)=O)C=C1)=O DEXFNLNNUZKHNO-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/02—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective
- G02B15/10—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by adding a part, e.g. close-up attachment
- G02B15/12—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by adding a part, e.g. close-up attachment by adding telescopic attachments
Description
この発明は、天体望遠鏡対物レンズの像側に装
着して、その焦点距離を拡大する為のリアコンバ
ージヨンレンズに関する。
リアコンバージヨンレンズは、従来のある対物
レンズの像側に装着するだけで、そのレンズをよ
り長焦点距離のレンズとして用いることができる
為、非常に便利なものであり、天体望遠鏡用とし
ては、いわゆるバーローレンズという名称でも良
く知られている。しかしながら、従来のこの種の
天体望遠鏡用リアコンバージヨンレンズは、強い
パワーの負レンズ系からなる為、天体望遠鏡の対
物レンズの如き球面収差の非常に小さいレンズに
装着した場合、高次の球面収差が発生すると共
に、ペツバール和は大きな負の値をもつ為、像面
湾曲が大となり、性能が大きく劣化する。それ
故、この種のリアコンバージヨンレンズは、単に
焦点距離を伸ばして星像の動きを検知する、いわ
ゆる案内望遠鏡としての用途しかもたなかつた。
本発明の目的は、簡単な構成であつて、大口径
の天体望遠鏡対物レンズに装着しても、球面収差
をはじめ、コマ収差、非点収差が極めて小さい、
リアコンバージヨンレンズを提供することにあ
る。具体的には、口径比が１：12程度の対物レン
ズに装着し、焦点距離の拡大倍率２倍のものを提
供するものである。
以下、本発明の構成を説明すると、対物レンズ
側より負（第１レンズ）、正（第２レンズ）、負
（第３レンズ）の順に配置された３枚のレンズよ
りなり、３群３枚あるいはレンズをはり合わせる
ことにより２群３枚または１群３枚のレンズとし
て構成され、次の条件をみたすことを特徴とする
レンズである。
(1) ｎ１＋ｎ３／２＞n2
(2) ν１＋ν３／２＞ν２＋５
(3) 1.5＜｜ｆ／f2｜＜4.0 （f2＜０）
(4) 0.3＜f1／f3＜3.3
ただし、ｆiは第ｉ番目のレンズの焦点距離、
ｎiは第ｉ番目のレンズのｄ線の屈折率、νiは第
ｉ番目のレンズのアツベ数、ｆはリアコンバージ
ヨンレンズ全系の合成焦点距離である。
次に、これらの条件について説明する。
条件(1)は、ペツバール和を改善する為の条件
で、負の第１レンズ及び第３レンズに屈折率の高
い硝材を使用し、かつ正の第２レンズに屈折率の
低い硝材を使用することを示し、この条件をはず
れると、ペツバール和は負の大きな値をもち、像
面湾曲が増大する。
条件(2)は、色収差補正の為の条件であり、対物
レンズで発生した色収差を極力おさえる為の、リ
アコンバージヨンレンズの色消し条件に相当す
る。条件(2)をはずれて、負レンズのアツベ数の平
均値が正レンズのアツベ数に近づくと、色収差の
補正が困難となる。
条件(3)は、正の第２レンズのパワーを適切な値
に保ち諸収差を良好に補正する条件で、上限をこ
えて第２レンズのパワーが強くなると、第２レン
ズの両面の曲率半径が著しく小さくなり、これら
の面で発生する高次の球面収差により、球面収
差、コマ収差が増大する。また下限をこえて第２
レンズのパワーが弱くなると、球面収差は良好に
保たれるが、色収差、特に２次スペクトルが増大
して好ましくない。
条件(4)は、負の第１レンズと第３レンズのパワ
ーの比を与えるものである。拡大率が２倍程度の
リアコンバージヨンレンズでは、負レンズのパワ
ーが非常に大きな値をもつため、これを第１レン
ズ、第３レンズに適切に分配することにより、負
のペツバール和の増大を防ぐと共に、諸収差の増
大を防ぐことが必要になる。この条件が(4)であ
り、条件(4)の上限をこえると、第３レンズが過大
なパワーをもち、また下限をこえると、第１レン
ズが過大なパワーをもち、どちらも負のペツバー
ル和が増大し、像面を良好に補正することが困難
になる。
以上のような具体的構成により、倍率が２倍で
あつて、口径比１：12程度の大口径な天体望遠鏡
の対物レンズに装着する高性能なリアコンバージ
ヨンレンズが得られる。例えば、焦点距離1000ミ
リ、口径比１：12の対物レンズに装着した場合、
合成焦点距離2000ミリ、口径比１：24の、諸収差
が十分小さく高性能な望遠鏡対物レンズとして使
用することができ、単に案内望遠鏡として高倍率
を得るのみならず、観測用としてはもちろん、写
真撮影用にも十分使用でき、焦点距離に比べ極め
てコンパクトな天体望遠鏡を得ることができる。
以下、本発明の実施例を示す。ここで、d0は対
物レンズの焦点位置よりリアコンバージヨンレン
ズの第１面までの間隔を示し、拡大率ｍは後述の
基準レンズの焦点位置より上記d0の間隔にて装着
したときの値である。また、実施例１，２，３は
それぞれ本発明を３群３枚、２群３枚、１群３枚
にて構成したものである。
実施例 １
The present invention relates to a rear conversion lens that is attached to the image side of an astronomical telescope objective lens to expand its focal length. A rear conversion lens is extremely convenient because it can be used as a longer focal length lens by simply attaching it to the image side of a conventional objective lens. It is also well known as the Barlow lens. However, since this type of conventional rear conversion lens for astronomical telescopes consists of a negative lens system with strong power, when it is attached to a lens with very small spherical aberration, such as an objective lens of an astronomical telescope, high-order spherical aberration occurs. Since the Petzval sum has a large negative value, the curvature of field becomes large and the performance is greatly degraded. Therefore, this type of rear conversion lens could only be used as a so-called guiding telescope, which simply increases the focal length and detects the movement of star images. The object of the present invention is to have a simple configuration, and to have extremely small spherical aberration, coma aberration, and astigmatism even when attached to a large-diameter astronomical telescope objective lens.
The purpose is to provide a rear conversion lens. Specifically, it is attached to an objective lens with an aperture ratio of about 1:12, and provides a focal length magnification of twice. The configuration of the present invention will be explained below. It consists of three lenses arranged in the order of negative (first lens), positive (second lens), and negative (third lens) from the objective lens side, and three lenses in three groups. Alternatively, the lens may be constructed as a lens with three lenses in two groups or three lenses in one group by gluing the lenses together, and is characterized by satisfying the following conditions. (1) n 1 + n 3 /2>n 2 (2) ν 1 +v 3 /2>ν 2 +5 (3) 1.5<|f/f 2 |<4.0 (f 2 <0) (4) 0.3<f 1 /f 3 <3.3 where f i is the focal length of the i-th lens,
n i is the d-line refractive index of the i-th lens, v i is the Abbe number of the i-th lens, and f is the combined focal length of the entire rear conversion lens system. Next, these conditions will be explained. Condition (1) is a condition for improving the Petzval sum, in which a glass material with a high refractive index is used for the negative first lens and the third lens, and a glass material with a low refractive index is used for the positive second lens. If this condition is violated, the Petzval sum has a large negative value and the curvature of field increases. Condition (2) is a condition for correcting chromatic aberration, and corresponds to an achromatic condition for the rear conversion lens to suppress chromatic aberration generated in the objective lens as much as possible. If condition (2) is violated and the average Abbe number of the negative lens approaches the Abbe number of the positive lens, it becomes difficult to correct chromatic aberration. Condition (3) is a condition in which the power of the positive second lens is kept at an appropriate value and various aberrations are well corrected, and when the power of the second lens becomes strong beyond the upper limit, the radius of curvature of both surfaces of the second lens increases. becomes significantly smaller, and higher-order spherical aberrations occurring on these surfaces increase spherical aberration and coma aberration. Also, the second level exceeds the lower limit.
When the power of the lens is weakened, spherical aberration is maintained well, but chromatic aberration, especially secondary spectrum, increases, which is not desirable. Condition (4) provides a negative power ratio between the first lens and the third lens. In a rear conversion lens with a magnification of about 2x, the power of the negative lens is extremely large, so by appropriately distributing this power to the first and third lenses, an increase in the negative Petzval sum can be prevented. At the same time, it is necessary to prevent increases in various aberrations. This condition is (4), and when the upper limit of condition (4) is exceeded, the third lens has excessive power, and when the lower limit is exceeded, the first lens has excessive power, and both have a negative Petzval. The sum increases, making it difficult to properly correct the image plane. With the above-described specific configuration, a high-performance rear conversion lens with double magnification and an aperture ratio of approximately 1:12 can be provided to be attached to the objective lens of a large-diameter astronomical telescope. For example, when attached to an objective lens with a focal length of 1000 mm and an aperture ratio of 1:12,
With a composite focal length of 2000 mm and an aperture ratio of 1:24, various aberrations are sufficiently small and it can be used as a high-performance telescope objective lens.It can be used not only as a guide telescope to obtain high magnification, but also for observation purposes and photography. It is possible to obtain an astronomical telescope that can be used for photographing and is extremely compact compared to its focal length. Examples of the present invention will be shown below. Here, d 0 indicates the distance from the focal position of the objective lens to the first surface of the rear conversion lens, and the magnification ratio m is the value when the lens is mounted at the distance d 0 above from the focal position of the reference lens, which will be described later. be. Further, in Examples 1, 2, and 3, the present invention was constructed by three groups with three elements, a second group with three elements, and a first group with three elements, respectively. Example 1
【表】 実施例 ２【table】 Example 2
【表】 実施例 ３【table】 Example 3
【表】
本実施例１〜３のリアコンバージヨンレンズ
を、特開昭54−59953号公報に示された天体望遠
鏡対物レンズを基準レンズとして、これに装着し
た場合の収差図を第２図、第４図及び第６図に示
す。これによれば、本実施例のリアコンバージヨ
ンレンズを装着しても、球面収差、色収差をはじ
め非点収差も十分小さく、天体望遠鏡として十分
な性能をもつていることがわかる。
なお、ここで使用した基準レンズの諸元は下記
の通りである。[Table] Figures 2 and 3 show aberration diagrams when the rear conversion lenses of Examples 1 to 3 are attached to the astronomical telescope objective lens disclosed in JP-A-54-59953 as a reference lens. This is shown in Figures 4 and 6. According to this, it can be seen that even when the rear conversion lens of this example is attached, spherical aberration, chromatic aberration, and astigmatism are sufficiently small, and the telescope has sufficient performance as an astronomical telescope. Note that the specifications of the reference lens used here are as follows.
第１図は本発明の実施例１のレンズ断面図、第
２図は実施例１のリアコンバージヨンレンズを基
準レンズに装着した場合の収差図、第３図は本発
明の実施例２のレンズ断面図、第４図は実施例２
のリアコンバージヨンレンズを基準レンズに装着
した場合の収差図、第５図は本発明の実施例３の
レンズ断面図、第６図は実施例３のリアコンバー
ジヨンレンズを基準レンズに装着した場合の収差
図である。
Fig. 1 is a cross-sectional view of a lens according to Example 1 of the present invention, Fig. 2 is an aberration diagram when the rear conversion lens of Example 1 is attached to a reference lens, and Fig. 3 is a cross-sectional view of a lens according to Example 2 of the present invention. Figure 4 is Example 2
5 is a cross-sectional view of the lens of Example 3 of the present invention, and FIG. 6 is an aberration diagram when the rear conversion lens of Example 3 is attached to the reference lens. It is a diagram.
Claims (1)
た３枚のレンズよりなり、３群３枚あるいはレン
ズをはり合わせることにより２群３枚または１群
３枚のレンズとして構成され、次の条件をみたす
ことを特徴とする天体望遠鏡用リアコンバージヨ
ンレンズ。 (1) ｎ１＋ｎ３／２＞n2 (2) ν１＋ν３／２＞ν２＋５ (3) 1.5＜｜ｆ／f2｜＜4.0 （f2＜０） (4) 0.3＜f1／f3＜3.3 ただし、ｆiは第ｉ番目のレンズの焦点距離、
ｎiは第ｉ番目のレンズのｄ線の屈折率、νiは第
ｉ番目のレンズのアツベ数、ｆはリアコンバージ
ヨンレンズ全系の合成焦点距離である。[Claims] 1 Consists of three lenses arranged in the order of negative, positive, and negative from the objective lens side, and three lenses in three groups, or three lenses in two groups or three lenses in one group by gluing the lenses together. A rear conversion lens for an astronomical telescope, which is configured as follows and satisfies the following conditions. (1) n 1 + n 3 /2>n 2 (2) ν 1 +v 3 /2>ν 2 +5 (3) 1.5<|f/f 2 |<4.0 (f 2 <0) (4) 0.3<f 1 /f 3 <3.3 where f i is the focal length of the i-th lens,
n i is the d-line refractive index of the i-th lens, v i is the Abbe number of the i-th lens, and f is the combined focal length of the entire rear conversion lens system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14912880A JPS5773714A (en) | 1980-10-24 | 1980-10-24 | Rear conversion lens for astronomical telescope |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14912880A JPS5773714A (en) | 1980-10-24 | 1980-10-24 | Rear conversion lens for astronomical telescope |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5773714A JPS5773714A (en) | 1982-05-08 |
| JPS6113735B2 true JPS6113735B2 (en) | 1986-04-15 |
Family
ID=15468334
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14912880A Granted JPS5773714A (en) | 1980-10-24 | 1980-10-24 | Rear conversion lens for astronomical telescope |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5773714A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0515864B2 (en) * | 1989-01-27 | 1993-03-02 | Keiichiro Yamazaki |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0629904B2 (en) * | 1984-07-02 | 1994-04-20 | キヤノン株式会社 | Converter lens |
| JPH0713705B2 (en) * | 1985-04-09 | 1995-02-15 | 株式会社ニコン | Rear conversion lens |
| TWI719659B (en) | 2019-10-03 | 2021-02-21 | 大立光電股份有限公司 | Imaging optical system, imaging apparatus and electronic device |
-
1980
- 1980-10-24 JP JP14912880A patent/JPS5773714A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0515864B2 (en) * | 1989-01-27 | 1993-03-02 | Keiichiro Yamazaki |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5773714A (en) | 1982-05-08 |
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