Zoom lens and image pickup apparatus having the same

Abstract

A zoom lens includes, in order from an object side to an image side, a lens unit Ln having the highest negative refractive power of all the following lens units, a lens unit Lm2 having positive refractive power, a lens unit Lm having negative refractive power, and a rear lens group Lp including one or more lens units and having overall positive refractive power. During zooming, a distance between every adjacent lens units varies. During focusing from an infinite distance to a minimum object distance, the lens unit Ln and the lens unit Lm move toward the object side. The focal length F Lm of the lens unit Lm and the focal length F Lm2 of the lens unit Lm2 are appropriately set.

What is claimed is: 
     
         1 . A zoom lens comprising, in order from an object side to an image side:
 a first lens unit having negative refractive power;   a second lens unit having positive refractive power;   a third lens unit having negative refractive power; and   a rear lens group including one or more lens units and having overall positive refractive power,   
       wherein during zooming, a distance between every adjacent lens units varies,
 wherein the first lens unit has the highest negative refractive power of all the lens units, 
 
       wherein during focusing from an infinite distance to a minimum object distance, the first lens unit and the third lens unit move toward the object side, and
 wherein the following condition is satisfied:
   0.65<|FL m /FL m 2|<1.50; and 
   0.5<|FL p /FL m |<1.0 
 
 where FLm is a focal length of the third lens unit, FLm2 is a focal length of the second lens unit, and FLp is a focal length of the rear lens group at a wide-angle end. 
 
     
     
         2 . A zoom lens comprising, in order from an object side to an image side:
 a first lens unit having negative refractive power;   a second lens unit having positive refractive power;   a third lens unit having negative refractive power; and   a rear lens group including one or more lens units and having overall positive refractive power,   wherein a distance between every adjacent lens units varies during zooming,   wherein the first lens unit has the highest negative refractive power of all the lens units,   
       wherein at least the first lens unit is moved toward the object side to perform focusing from an infinite distance to a predetermined finite distance,
 wherein at least the first lens unit and the third lens unit move towards the object side at a telephoto end to perform macrofocusing on an object distance being shorter than the predetermined finite distance, and 
 wherein the following condition is satisfied:
   0.65<|FL m /FL m 2|<1.50 
 
 where FLm is a focal length of the third lens unit, and FLm2 is a focal length of the second lens unit. 
 
     
     
         3 . An image pickup apparatus comprising:
 a zoom lens; and   a solid-state image sensor configured to receive an image formed by the zoom lens,   wherein the zoom lens comprises, in order from an object side to an image side:
 a first lens unit having negative refractive power; 
 a second lens unit having positive refractive power; 
 a third lens unit having negative refractive power; and 
 a rear lens group including one or more lens units and having overall positive refractive power, 
   
       wherein during zooming, a distance between every adjacent lens units varies,
 wherein the first lens unit has the highest negative refractive power of all the lens units, 
 
       wherein during focusing from an infinite distance to a minimum object distance, the first lens unit and the third lens unit move toward the object side, and
 wherein the following condition is satisfied:
   0.65<|FL m /FL m 2|<1.50; and 
   0.5<|FL p /FL m |<1.0 
 
 where FLm is a focal length of the third lens unit, FLm2 is a focal length of the second lens unit, and FLp is a focal length of the rear lens group at a wide-angle end. 
 
     
     
         4 . An image pickup apparatus comprising:
 a zoom lens; and   a solid-state image sensor configured to receive an image formed by the zoom lens,   wherein the zoom lens comprises, in order from an object side to an image side:
 a first lens unit having negative refractive power; 
 a second lens unit having positive refractive power; 
 a third lens unit having negative refractive power; and 
 a rear lens group including one or more lens unit and having overall positive refractive power, 
   
       wherein a distance between every adjacent lens units varies during zooming,
 wherein the first lens unit has the highest negative refractive power of all the lens units, 
 wherein at least the first lens unit is moved toward the object side to perform focusing from an infinite distance to a predetermined finite distance, 
 wherein at least the first lens unit and the third lens unit move towards the object side at a telephoto end to perform macrofocusing on an object distance being shorter than the predetermined finite distance, and 
 wherein the following condition is satisfied:
   0.65<|FL m /FL m 2|<1.50 
 
 where FLm is a focal length of the third lens unit, and FLm2 is a focal length of the second lens unit. 
 
     
     
         5 . A zoom lens comprising, in order from an object side to an image side:
 a first lens unit having negative refractive power;   a second lens unit having positive refractive power;   a third lens unit having negative refractive power; and   a rear lens group including one or more lens units and having overall positive refractive power,   wherein during zooming, a distance between every adjacent lens units varies,   wherein the first lens unit has the highest negative refractive power of all the lens units,   wherein the at least first lens unit is moved toward the object side to perform focusing from an infinite distance to a predetermined finite distance, and   wherein at least the first lens unit and the third lens unit move towards the object side at a telephoto end to perform macrofocusing on an object distance being shorter than the predetermined finite distance.   
     
     
         6 . An image pickup apparatus comprising:
 a zoom lens; and   a solid-state image sensor configured to receive an image formed by the zoom lens,   wherein the zoom lens comprises, in order from an object side to an image side:
 a first lens unit having negative refractive power; 
 a second lens unit having positive refractive power; 
 a third lens unit having negative refractive power; and 
 a rear lens group including one or more lens units and having overall positive refractive power, 
   
       wherein during zooming, a distance between every adjacent lens units varies,
 wherein the first lens unit has the highest negative refractive power of all the lens units, 
 wherein at least the first lens unit is moved toward the object side to perform focusing from an infinite distance to a predetermined finite distance, and 
 wherein at least the first lens unit and the third lens unit move toward the object side at a telephoto end to perform macrofocusing on an object distance being shorter than the predetermined finite distance.