| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable imaging optical system sufficiently reduced in size while coping with a large imaging element in an electrophotographic imaging device, such as a digital still camera and digital video camera, which employs a large imaging element. SOLUTION: The variable imaging optical system includes, in order from an object side, a first lens group of negative refractive power, a second lens group of positive refractive power, and a third lens group of negative refractive power. The third lens group is composed of 3a lens group and 3b lens group of negative refractive power. When focusing to a close distance takes place, the 3b lens group moves to satisfy a predetermined conditional formula. COPYRIGHT: (C)2011,JPO&INPIT |
