WIDE-ANGLE LENS

• Main Authors: UEDA HIROYASU, KUBOTA YOJI, ISHIZAWA KOJI
• Format: Patent
• Language: English; Japanese
• Published: 29.07.2021
• Subjects: OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

To provide a wide-angle lens which offers good imaging performance at each wavelength within a wide wavelength range.SOLUTION: A wide-angle lens 10 is provided, comprising first and second lenses L1, L2 having convex surfaces on the object side and a composite focal length f12, a third lens L3 having high positive power and a large Abbe number, a fourth lens L4 having low power, a fifth lens L5 having positive power, and a sixth lens L6 having negative power, arranged in order from the object side. A focal length of each lens f12, f3-f6 and Abbe numbers νd1-νd6 satisfy each of the following conditional expressions: -2.5<f12/f<-0.5, 1.0<f3/f<4.0, 18<|f4/f|, 0.7<|f5/f6|<1.5, 1.0<d23/f<4.0;2.0<νd5/νd6<5.0, 45.0<νd3, 35.0<(νd1+νd2)/2, where f represents a focal length of the entire lens system and d23 represents a distance between the second lens and the third lens.SELECTED DRAWING: Figure 1A 【課題】広波長帯域に及ぶ各波長に対して良好な結像性能の広角レンズを提供する。【解決手段】広角レンズ１０は、物体側より順に、物体側に凸で合成焦点距離ｆ１２の第１、第２レンズＬ１、Ｌ２と、強い正のパワーと大きなアッベ数の第３レンズＬ３と、パワーの弱い第４レンズＬ４と、正のパワーの第５レンズＬ５と、負のパワーの第６レンズＬ６とが配置される。レンズ系全体の焦点距離をｆ、第２、第３レンズ間距離をｄ２３とすると、各レンズの焦点距離ｆ１２、ｆ３〜ｆ６、アッベ数νｄ１〜νｄ６は以下の各条件式を満たす。−２．５＜ｆ１２／ｆ＜−０．５；１．０＜ｆ３／ｆ＜４．０；１８＜｜ｆ４／ｆ｜；０．７＜｜ｆ５／ｆ６｜＜１．５；１．０＜ｄ２３／ｆ＜４．０；２．０＜νｄ５／νｄ６＜５．０；４５．０＜νｄ３；３５．０＜（νｄ１＋νｄ２）／２【選択図】図１Ａ