Patent ID: 8284501

Claim:
An optical imaging system, comprising: a first lens group having a positive or negative optical power, an aperture diaphragm, and a second lens group having a positive optical power arranged in order from an object side, wherein the first lens group is comprised of a first front lens group including at least two negative lenses and a first rear lens group having at least one positive lens with an airspace in-between the first front and rear lens groups, the airspace being largest among airspaces in the first lens group; the second lens group is comprised of a second front lens group including a first positive lens, a first negative lens, a second negative lens, and a second positive lens arranged in order from the object side, and a second rear lens group including at least one aspherical lens; when focusing on an object in a close range from infinity, the second lens group is configured to move to the object side; and the first and second lens groups are configured to move in such a manner as to satisfy the following condition when focusing on an object at infinity: 0.3 <D — S 2 /D — 1 S< 2.0 where D — 1S is an interval between the first lens group and the aperture diaphragm and D — 2S is an interval between the second lens group and the aperture diaphragm.