| 摘要 |
PURPOSE:To obtain a lens of a small front lens diameter with small chromatic aberration by decreasing the front lens diameter by arranging a negative lens at the front and then by satisfying prescribed conditions to corrent various aberrations. CONSTITUTION:The lens system consists of the 1st and 2nd group negative meniscus lenses, the 3rd group positive lens, the 4th cemented lens with positive refraction power, the 5th group negative lens, the 6th group positive lens, the 7th group cemented lens with negative refraction power, the 8th group positive meniscus lens, and the 9th positive lens. Further, conditional equations (1)-(4) should be satisfied [where (f) is the focal length of the whole system, fI-V the composite focal length of the 1st-5th groups, f4 and f4' the focal lengths of the single lenses of the 4th group, nu4 and nu4' their Abbe numbers, rIV and rVII the radii of curvature of the junction surfaces of the 4th and 7th groups, and rV-F the radius of curvature of the front surface of the 5th group lens]. Condition (1) regards compacting, condition (2) the correction of magnification chromatic aberration, conditions (2) and (3) the correction of chromatic aberration, and condition (4) the correction of spherical aberration. |
