| 摘要 |
PURPOSE:To obtain a small-sized, high-performance lens which has a large zoom ratio by providing the 1st positive group, the 2nd group as a negative variator, the 3rd group as a compensator, and the 4th and the 5th groups which have aspherical surface as a relay system. CONSTITUTION:The lens consists of the 1st group 1 as a positive focusing part, the 2nd group 2 as a negative variator, the 3rd group 3 as a compensator for holding an image plane constant, and the 4th group 4 and the 5th group as the relay system. The 4th group 4 consists of a positive single lens and a surface r14 is an aspherical surface. The 5th group 5 consists of a meniscus cemented lens having a concave surface on the object side and a positive single lens, and a surface r18 is an aspherical surface. Those aspherical surfaces compensate large-diameter aperture aberrations and off-axis aberrations. The ranges of the focal lengths of the 2nd - the 5th 2-5, the focal length of the meniscus cemented lens, etc., are limited to obtain a video camera lens which has a 1.4F value and an about x6 zoom ratio. |
