| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an ultra wide-angle lens system that employs a high-performance inner focusing system with compactness and low aberration fluctuation due to focusing despite the ultra wide-angle lens system with a photographing angle-of-view exceeding 120°. <P>SOLUTION: An ultra wide-angle lens system includes, in order from an object side, a first lens group G1 with negative refractive power and a second lens group G2 with positive refractive power. The first lens group is composed of a first A lens group with negative refractive power and a first B lens group with negative refractive power. Further, the first A lens group is composed of a first lens L1 of a negative meniscus lens and a second lens L2 of a negative meniscus lens with an aspherical surface on at least one surface. The first B lens group is composed of a third lens L3 of a negative meniscus lens with an aspherical surface on at least one surface. In focusing, the first B lens group is moved to the object side. <P>COPYRIGHT: (C)2012,JPO&INPIT |
