Patent ID: 7446946

Claim:
A zoom optical system comprising: a plurality of optical groups with variable optical power arranged along an optical axis; and at least one optical group with constant optical power arranged along the optical axis, wherein the system is zoomed by changing the power of at least one of the plurality of the optical groups with variable optical power, wherein the plurality of the optical groups with variable optical power each includes a rotationally asymmetric surface and each has a plurality of optical devices, which change the power within the respective optical groups by moving the respective optical devices in a direction different from the optical axis, and wherein the system at a telephoto end satisfies the condition: |φdt|≦|φst|, where |φdt| is the absolute value of the power total sum of a plurality of the optical groups with variable optical power, and |φst| is the absolute value of the power total sum of the at least one optical group with constant optical power.