This specification discloses an image taking lens system which can quickly effect
focusing from an infinity object to a short-distance object. The image taking lens
system disclosed in the present specification has, in succession from an object
side to an image side, a first lens unit, a second lens unit, a third lens unit
and a fourth lens unit. In case of focusing from the infinity object to the short-distance
object, the first lens unit is not moved, but the second lens unit is moved to
the image side and the third lens unit is moved to the object side. The principal
point interval between the first lens unit and the second lens unit is a negative value.
