| 摘要 |
A wide angle objective of the retrofocus type, with an increased aperture, is disclosed. This objective comprises three lens groups of which the first counting from the front has a negative power and includes, from front to rear, a positive lens in the meniscus form convex toward the front, a negative lens in the meniscus form convex toward the front, a negative lens likewise in the meniscus form convex toward the front, a positive lens, and a negative lens in the meniscus form convex toward the front. The second lens group includes a cemented bi-convex lens, and the third lens group includes a cemented lens of positive and negative lens elements, a positive lens in the meniscus form convex toward the rear, a cemented lens of negative and positive lens elements, and a positive lens. A diaphragm is positioned in the space between the second and third lens groups. Various conditions are prescribed for every lens group, and for every lens in each group.
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