OPTICAL SYSTEM AND IMAGE PICKUP APPARATUS INCLUDING THE SAME

Provided is an optical system including, in order from an object side to an image side, a front lens unit, an aperture stop, and a rear lens unit. The front lens unit consists of a positive lens and a diffractive optical element, which are arranged in order from the object side to the image side. The diffractive optical element consists of a plurality of lenses that are cemented to each other, and at least one of cemented surfaces of the plurality of lenses is a diffractive surface. An interval on an optical axis between the positive lens and the diffractive optical element is the largest among intervals on the optical axis between two lenses that are adjacent in the optical system.