JPS59159117A - Rear focus type lens - Google Patents
Rear focus type lensInfo
- Publication number
- JPS59159117A JPS59159117A JP58033441A JP3344183A JPS59159117A JP S59159117 A JPS59159117 A JP S59159117A JP 58033441 A JP58033441 A JP 58033441A JP 3344183 A JP3344183 A JP 3344183A JP S59159117 A JPS59159117 A JP S59159117A
- Authority
- JP
- Japan
- Prior art keywords
- focusing
- lens group
- lens
- stop
- moving
- 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.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/144—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only
- G02B15/1441—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive
- G02B15/144113—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive arranged +-++
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
Abstract
Description
【発明の詳細な説明】
くはカラービデオカメラ等のカラーカメラに適したリア
フォーカス型のレンズ又はズームレンズに関するもので
ある。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rear focus type lens or zoom lens suitable for a color camera such as a color video camera.
一般に、色分解プリズム、ストライプフィルター、ある
いはモザイクフィルター等の色分解光学系を有するカラ
ーカメラについては、良好な色再現特性を得るために、
射出瞳距離が大きい（望ましくは２００〜３００朋以上
理想的には無限遠）ことと共に、その距離が変化しない
ことがよ臂とされている。また実用上の必要性から構成
されることのある射出瞳距離の短かいものについても色
再現性の電、気的補正を行なう上で射出瞳距離の変化し
ないことがよい。In general, in order to obtain good color reproduction characteristics for color cameras that have color separation optical systems such as color separation prisms, stripe filters, or mosaic filters,
It is recommended that the exit pupil distance is large (preferably 200 to 300 mm or more, ideally infinity) and that the distance does not change. In addition, even when the exit pupil distance is short, which may be constructed due to practical necessity, it is preferable that the exit pupil distance does not change in order to perform electrical and mechanical correction of color reproducibility.
ところが、絞シよυ像側に位置するレンズ群をフォーカ
シングのために移動させる形式の所謂リアフォーカス型
レンズが、重量の点や、移動レンズ群とカメラ本体の距
離が短かいのでフォーカシングのだめのメカ的信号伝達
の上で有利であるという理由から、近時において実用に
供される傾向にある。However, so-called rear focus lenses, in which the lens group located on the image side of the aperture is moved for focusing, are difficult to use due to their weight and the short distance between the moving lens group and the camera body. Since it is advantageous in terms of signal transmission, it has recently been put into practical use.
しかしこの形式のリアフォーカス型レンズは絞シよｐ像
側のレンズ群が移動する結果として通常射出瞳位置が変
化し、色分解光学系を有するカラーカメラでは色再現性
の点で問題が生ずる〇この問題はズーミングのための移
動レンズ群を含むズームレンズにおいても同様である。However, with this type of rear focus lens, the exit pupil position usually changes as a result of the movement of the lens group on the p-image side due to the aperture, which causes problems in terms of color reproducibility in color cameras with color separation optical systems. This problem also applies to zoom lenses that include a moving lens group for zooming.
そこで本発明においては、絞シよシ像側にフォーカシン
グのだめの移動レンズ群を有するリアフォーカス型レン
ズつき、射出瞳位置がフォーカシングによっても変化し
ないようにすることを目的としてなされたものである。Therefore, the present invention is designed to provide a rear focus type lens having a moving lens group for focusing on the image side of the diaphragm so that the exit pupil position does not change even when focusing.
面してこの目的を達成するための本発明の要旨とすると
ころは、少なくとも絞シよｐ像側にフォーカシング用の
移動レンズ群を複数配設し、これらレンズ群の連係した
移動によシ絞シを物点と考えた場合像点位置が変化しな
いようにフォーカシングのだめのレンズ群の移動軌跡を
限定し一絞シを固定のまま実質的に射出瞳位置を一定に
保つようにしたリアフォーカス型レンズにある。The gist of the present invention to achieve this objective is to provide a plurality of moving lens groups for focusing at least on the p-image side of the aperture, and to move the aperture in conjunction with the movement of these lens groups. Rear focus type that limits the movement locus of the lens group for focusing so that the image point position does not change when considering the image point as the object point, and keeps the exit pupil position substantially constant while fixing the first aperture. It's in the lens.
なおここで射出瞳位置が実質的に一定位置に保たれると
け、厳密に一定位置に保たれる場合は勿論、色再現性に
関し実用上支障のない範囲内で射出瞳位置の変化を許容
する場合を含むことをいう。Note that as long as the exit pupil position is kept at a substantially constant position, it goes without saying that the exit pupil position is allowed to change within a range that does not cause any practical problems in terms of color reproducibility, as long as it is kept at a strictly constant position. This includes cases.
以下本発明を図面に示す実施態様に従って説明する。The present invention will be explained below according to embodiments shown in the drawings.
図面は本発明よシなるリアフォーカス型レンズの構成概
要を示し、物体側よシ順に、７オーカシングに関して固
定の第１正レンズ群Ｌ１、および第２負レンズ群Ｌ２、
絞シＳ３フォーカシングのために移動する第３正レンズ
群Ｌ３および第４正レンズ群Ｌ４を配して構成されてい
る。The drawing shows an outline of the configuration of a rear focus type lens according to the present invention, and in order from the object side, there is a first positive lens group L1 fixed with respect to 7 focusing, a second negative lens group L2,
The aperture S3 is configured by disposing a third positive lens group L3 and a fourth positive lens group L4 that move for focusing.
なセ図の下半部に示した矢印線はフォーカシング時にお
ける各レンズ群Ｌ３＋Ｌ４の光軸上での動きの関係を示
している。The arrow lines shown in the lower half of the diagram indicate the relationship between the movements of the lens groups L3+L4 on the optical axis during focusing.
そして前記構成において、絞りより像側のレンズ群Ｌ３
＋Ｌ４ を移動させてフォーカシングを行なうに際し、
これらの移動量の比率を、絞Ｄｓを被写体とみたときの
前記レンズ群Ｌ３ｔＬ４による像点（全糸の射出瞳位置
に相当する）が一定となるように定めている。このこと
によって絞シよシ像側のレンズ群（本例ではｒ、、３ｓ
Ｌ４ ）を移動させて７オーカシングを行なっても
射出瞳位置は一定に保たれることになυ、このようなレ
ンズ系を色分解光学系を有するカラーカメラに用いたと
きにも良好な色再現性が得られるのである。In the above configuration, the lens group L3 on the image side of the aperture
When performing focusing by moving +L4,
The ratio of these moving amounts is determined so that the image point (corresponding to the exit pupil position of all threads) by the lens group L3tL4 is constant when the diaphragm Ds is viewed as a subject. This allows the lens group on the image side from the aperture (in this example, r, 3s
Even if L4) is moved and 7-ocusing is performed, the exit pupil position remains constant υ, and even when such a lens system is used in a color camera with a color separation optical system, good color reproduction is achieved. You can gain sex.
次ぎに本実施例における数値例を記載する。Next, numerical examples in this example will be described.
（５） −
前−記載よシ明らかなようにフォーカシングによっても
射出瞳位置は変化しないことが理解されようＯ
なお、レンズ群Ｌ３１Ｌ４の移動はカム手段等によって
行なわせればよい。(5) As is clear from the above description, it will be understood that the exit pupil position does not change even with focusing. Note that the lens group L31L4 may be moved by cam means or the like.
上記実施例は固定焦点距離レンズの場合を示しているが
、絞よシ物体側のレンズ糸が変倍力を持つズームレンズ
の場合でも７オーカシングのためのレンズ群Ｌ３ｙＬ４
の移動軌跡は全く同じになる。但しこの場合は、ズーミ
ングに従って同一被写体距離に対する繰り出し量が異な
るので焦点距離変化に伴いレンズ群Ｌ３ｔＬ４の移動量
を対応して変化させる必要が生ずる。又後よシ像側のレ
ンズ群をズーミング時に移動せしめて変倍に寄与させる
ことも可能であシ、この場合レンズ３．′４は変倍と７
オーカシングの二つの機能を兼ねることになる・
また絞シより像側の複数のレンズ群を移動させる方法と
゛して、中間に固定部を設けた場合には、一般によく知
られているように中間に固定レンズを配置しその前後の
レンズを同一量変化させることによシ実質的にピント位
置を同一に保つものを光学的補正型ズームレンズと呼ば
れているが、これと同一原理で絞シを被写体として光学
補正型ズームレンズを構成し一方この移動が被写体にと
ってフォーカシングの作用をさせることによシ、カム手
段を用いることなく本発明の目的を達成することができ
る。The above embodiment shows the case of a fixed focal length lens, but even in the case of a zoom lens in which the lens thread on the object side of the aperture has variable magnification power, the lens group L3yL4 for 7-focusing can be used.
The movement trajectory will be exactly the same. However, in this case, since the amount of extension for the same subject distance differs according to zooming, it is necessary to change the amount of movement of the lens group L3tL4 correspondingly as the focal length changes. It is also possible to move the lens group on the rear image side during zooming to contribute to variable magnification; in this case, the lens group 3. '4 is variable magnification and 7
It also serves the two functions of focusing. Also, when a fixed part is provided in the middle as a method of moving multiple lens groups on the image side from the diaphragm, as is generally well known, the intermediate An optically corrected zoom lens is a lens that maintains the same focus position by placing a fixed lens on the front and rear lenses by the same amount. The object of the present invention can be achieved without using a cam means by configuring an optically corrected zoom lens using the object as a subject, and by causing this movement to have a focusing effect on the subject.
ここで射出瞳位置を実質的に一定に保つとは、既述した
ように実用上支障のない範囲で位置変化を許容する意味
である。Here, keeping the exit pupil position substantially constant means allowing the position to change within a range that does not cause any practical problems, as described above.
以上説明したように本発明によれば、リアフォーカスと
いうレンズのコンパクト化達成手段に伴って生じる射出
瞳位置の変化を無くすことができ、色分解光学系を有す
るカラービデオカメラ等のカラーカメラにこれを適用し
た場合、良好な色再現性を得ることができその有用性は
大なるものである。As explained above, according to the present invention, it is possible to eliminate changes in the exit pupil position that occur due to rear focus, which is a means for achieving lens compactness, and this can be applied to a color camera such as a color video camera having a color separation optical system. When applied, good color reproducibility can be obtained and its usefulness is great.
【図面の簡単な説明】
図面は本発明の一実施例を示すリアフォーカス本 多
小 平 ””’ニーｔ＝１二
岸 １） 正 行 （ｆ、（２＋ｊ
−１
新 部 興 治 １
−１１− 〕[Brief Description of the Drawings] The drawings show an embodiment of the present invention. - 〕
Claims (1)
レンズ群を鳴し、フォーカシング時におけるこれらレン
ズ群の移動を割出瞳位置を実質的に一定に保って行なわ
せることを特徴とするリアフォーカス型レンズ。A rear focus type lens characterized in that a plurality of movable focusing lens groups are activated at least on the image side of the aperture, and the movement of these lens groups during focusing is performed while keeping an indexed pupil position substantially constant.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58033441A JPS59159117A (en) | 1983-03-01 | 1983-03-01 | Rear focus type lens |
| US06/582,457 US4708444A (en) | 1983-03-01 | 1984-02-22 | Photographic objective |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58033441A JPS59159117A (en) | 1983-03-01 | 1983-03-01 | Rear focus type lens |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS59159117A true JPS59159117A (en) | 1984-09-08 |
Family
ID=12386615
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58033441A Pending JPS59159117A (en) | 1983-03-01 | 1983-03-01 | Rear focus type lens |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59159117A (en) |
-
1983
- 1983-03-01 JP JP58033441A patent/JPS59159117A/en active Pending
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