| 摘要 |
PROBLEM TO BE SOLVED: To provide a photographic optical system that has a compact design, a wide angle of view and a large diameter as a whole while, ensuring a long back focus, and to provide a photographic lens unit and a camera. SOLUTION: Using thick lenses, an ample optical length for ambient light velocity is ensured to realize a wide angle of view. Since correction of spherical surface aberrations, resulting from aperture diameter increase, are shared by the object-side positive lenses enables realizing a compact design, wide angle of view and a large aperture as a whole, while ensuring long back focus. COPYRIGHT: (C)2007,JPO&INPIT
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