Patent ID: 8238039
Filing Date: 2012-08-07
Classification: G02B,G03B

Abstract:
1. A variable power optical system comprising, in order from the object side: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; and a fourth lens unit having a positive refractive power, wherein during variation in power from a wide-angle end state to a telephoto end state, a space between the first lens unit and the second lens unit increases, a space between the second lens unit and the third lens unit decreases, and a space between the third lens unit and the fourth lens unit varies, wherein a part of the third lens unit is configured to move in directions perpendicular to the optical axis, the variable power optical system satisfying conditions of the following expressions: where fw is a focal length of the entire system in the wide-angle end state, ft a focal length of the entire system in the telephoto end state, f3 a focal length of the third lens unit, Δd1 an axial moving distance of the first lens unit upon zooming from a wide-angle end state to a telephoto end state, and Lw an overall length in the wide-angle end state.