Patent attributes
A zoom optical system includes followings: a plurality of lens units for magnification, the plurality of lens unit for zooming including in order from a reduction conjugate side to a magnification conjugate side, a first lens unit having a positive optical power, a second lens unit having a negative optical power and a third lens unit having a positive optical power, wherein during zooming, respective intervals between the above described first, second and third lens unit vary, and across the entire zooming range, a magnification-side conjugate position with respect to a reduction-side conjugate position and a position of a pupil of the above described zoom optical system with respect to a reduction-side conjugate position are substantially immobile respectively.
