Zoom optical system and image pickup apparatus provided with the same

An image pickup apparatus comprising:

• a zoom optical system;
• and
• an image pickup element;
• wherein the zoom optical system comprises:
• a first group having a prism component, the prism component being arranged on an utmost object side in the zoom optical system and comprising an entrance surface having a concave surface directed toward the object side, a reflecting surface and an exit surface;
• two or more moving optical units arranged on an image side of the first group and configured to be movable in zooming;
• a last group arranged on an utmost image side in the zoom optical system and having positive refracting power;
• and
• an aperture stop arranged between the first group and the last group;
• wherein, when zooming is carried out from a wide angle end to a telephoto end, an entrance pupil formed by the aperture stop is moved toward the object side and an exit pupil formed by the aperture stop in an optical system arranged on the object side of the last group is moved toward the object side;
• wherein the last group comprises a lens component having an object-side surface which is a first aspherical surface and an image-side surface which is a second aspherical surface, the second aspherical surface having a convex face directed toward the image side near an optical axis and having a point of inflection on a cross-section taken along the optical axis;
• and
• wherein the first aspherical surface and the second aspherical surface satisfy the following conditions (3) to (5):
• 0.08<(ha11−ha07)/I<0.3 (3)
• −0.1<ha07/I<0.07 (4)
• 0.45<Cb/I<1 (5)
• where ha07 is a distance, in a direction along the optical axis, from a reference plane to the first aspherical surface at a height of 35% of an effective diagonal length of the image pickup element from the optical axis;
• ha11 is a distance, in the direction along the optical axis, from the reference plane to the first aspherical surface at a height of 55% of the effective diagonal length of the image pickup element from the optical axis;
• I is 50% of the effective diagonal length of the image pickup element;
• and Cb is a height from the optical axis to the point of inflection of the second aspherical surface, the reference plane being determined as normal to the optical axis and tangent to the first aspherical surface at a vortex thereof and a distance from the reference plane in a direction toward an image side being given a positive value.