INNER FOCUS MACROLENS AND IMAGE PICKUP DEVICE USING THE SAME

摘要

This disclosure is directed to an inner focus macrolens. The inner focus macrolens can include sequentially from an object side, a first lens unit, an aperture stop, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power and a fourth lens unit having a positive refractive power, wherein the first lens unit comprises a negative lens as the closest powered lens to the object side and a positive lens, the second lens unit comprises an object side negative lens as the closest powered lens to the object side and a positive lens, the third lens unit comprises a negative lens, and the fourth lens unit comprises a positive lens.

主权项

1. An inner focus macrolens comprising sequentially from an object side:
a first lens unit; an aperture stop; a second lens unit having a positive refractive power; a third lens unit having a negative refractive power; and a fourth lens unit having a positive refractive power, wherein the first lens unit comprises a negative lens as the closest powered lens to the object side and a positive lens, the second lens unit comprises an object side negative lens as the closest powered lens to the object side and a positive lens, the third lens unit comprises a negative lens, the fourth lens unit comprises a positive lens, wherein focusing is performed by moving the third lens unit toward an image side, and the inner focus macrolens satisfies conditional expressions (1) and (2):
−5≦(1−β32)×β42≦−2  (1)−4≦(R2f+R2r)/(R2f−R2r)≦0.4  (2)wherein
β3 is a lateral magnification of the third lens unit in focusing on an infinity object, β4 is a lateral magnification of the fourth lens unit in focusing on the infinity object, R2f is a radius of curvature of an object side surface of the object side negative lens, and R2r is a radius of curvature of an image side surface of the object side negative lens.