Zoom lens and image pickup apparatus using the same

摘要

A zoom lens includes in order from an object side to an image 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 negative refractive power, and the fourth lens unit includes at least two lenses. At the time of zooming from a wide angle end to a telephoto end, a distance between the first lens unit and the second lens unit widens, a distance between the second lens unit and the third lens unit narrows, a distance between the third lens unit and the fourth lens unit fluctuates, and the first lens unit, after moving toward the image side, moves toward the object side.

主权项

1. A zoom lens comprising in order from an object side to an image 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 negative refractive power, wherein the fourth lens unit includes at least two lenses, and at the time of zooming from a wide angle end to a telephoto end, a distance between the first lens unit and the second lens unit widens, a distance between the second lens unit and the third lens unit narrows, and a distance between the third lens unit and the fourth lens unit fluctuates, and the total number of lens units included in the zoom lens is four, and the first lens unit, after moving toward the image side, moves toward the object side, wherein the following conditional expression (1) is satisfied:
0.65<β2t/β3t<5  (1) where, β2t denotes a magnification of the second lens unit at the telephoto end, and β3t denotes a magnification of the third lens unit at the telephoto end, and each of β2t and β3t is a magnification when focused at an infinite object point.