A lens device having a function of varying a magnification of the lens
device and a function of focusing includes, in the order from an object
side to an image side, a first lens unit which has a positive optical
power and which is fixed during the variation of magnification, a second
lens unit which has a negative optical power and which moves during the
variation of magnification, and a third lens unit which has a positive
optical power and which is fixed during the variation of magnification.
The third lens unit includes a first lens sub-unit which is fixed during
focusing, a second lens sub-unit which has a positive optical power and
which moves during focusing, and a third lens sub-unit which has a
positive optical power and which is fixed during focusing, in that order
from the object side to the image side.