| 摘要 |
PROBLEM TO BE SOLVED: To provide an inner focus-type lens that is compact and a wide angle, and has excellent imaging performance with a large aperture even if the lens has about 45 mm focal length when converted to a 35 mm camera.SOLUTION: The inner focus-type lens comprises: a first lens group Gthat has positive refractive power; a second lens group Gthat has negative refractive power; and a third lens group Gthat has positive refractive power, which are sequentially arranged in order from an object side. The first lens group Gis composed of a front group Gthat has negative refractive power, an aperture stop STP that defines a predetermined aperture and a rear group Gthat has positive refractive power, which are sequentially arranged in order from the object side. The second lens group Gis composed of a negative lens L. The second lens group Gperforms a focusing by moving along an optical axis. Then, a predetermined condition is satisfied and thereby the inner focus-type lens can be attained that is compact and the wide-angle, and has the excellent imaging performance with the large aperture. |
