| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical system easily obtaining an image of high quality in the whole area of a display while having an entire system which is small sized and wide angle and easily maintaining a good optical performance even while being vibration proof.SOLUTION: An optical system is composed of a first lens group, an aperture diaphragm, and a second lens group with positive refractive power, in this order from the object side to the image side. The first lens group is composed of an eleventh lens with negative refractive power and a twelfth lens with positive refractive power in this order from the object side to the image side. The second lens group includes: a cemented lens having a twenty first p lens with positive refractive power and a twenty first n lens with negative refractive power cemented together; a twenty second lens with negative refractive power with a concave surface facing the object side; and a twenty third lens with positive refractive power with a convex surface facing the image side, in this order from the object side to the image side. The distance D1 from a lens face apex on the object side of the eleventh lens to the aperture diaphragm and the distance Dt from the lens face apex on the object side of the eleventh lens to the image surface are to be respectively suitably set. |
