Zoom lens

A zoom lens comprising a front lens group having a first lens unit of positive refractive power, a second lens unit of negative refractive power and a third lens unit of positive refractive power in this order from the object side and whose overall refractive power when in the wide angle end is positive, and a rear lens group having a positive lens unit and a negative lens unit, wherein when zooming from the wide angle end to the telephoto end, said first, said second and said third lens units axially move in such relation that the overall refractive power is weaker when in the telephoto end than when in the wide angle end, and said positive lens unit of said rear lens group and said negative lens unit of said rear lens group axially move in such relation that the separation therebetween narrows, whereby letting the focal length of the i-th lens unit be denoted by fi, the shortest focal length of the entire system by fW and the lateral magnification for the wide angle end of the i-th lens unit by .beta.iW, the following conditions are satisfied:

• 0.45<.vertline.f5/fW.vertline.<1.5
• 1.1<.beta.5W<1.9.
• 9.

A zoom lens comprising a front lens group having a first lens unit of negative refractive power, a second lens unit of positive refractive power and a third lens unit of positive refractive power in this order from the object side and whose overall refractive power when in the wide angle end is positive, and a rear lens group having a positive lens unit and a negative lens unit, wherein when zooming from the wide angle end to the telephoto end, said first, said second and said third lens units axially move in such relation that the overall refractive power of said front lens group is weaker in the telephoto end than in the wide angle end, and said positive lens unit of said rear lens group and said negative lens unit of said rear lens group axially move in such relation that the separation therebetween narrows.

A zoom lens comprising a front lens group having a first lens unit of negative refractive power, a second lens unit of negative refractive power and a third lens unit of positive refractive power in this order from the object side and whose overall refractive power when in the wide angle end is positive, and a rear lens group having a positive lens unit and a negative lens unit in this order from the object side, wherein when zooming from the wide angle end to the telephoto end, said first lens unit, said second lens unit and said third lens unit axially move in such relation that the overall refractive power of said front lens group is weaker in the telephoto end than in the wide angle end, and said positive lens unit of said rear lens group and said negative lens unit of said rear lens group axially move in such relation that the separation therebetween narrows.

A zoom lens comprising, from front to rear, a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of negative refractive power, a fourth lens unit of positive refractive power and a fifth lens unit of negative refractive power, wherein all said lens units axially move in such relation that when in the telephoto end as zoomed from the wide angle end, the separation between said first and said second lens units is shorter, the separation between said second and said third lens unit is longer, the separation between said third and said fourth lens unit is longer, and the separation between said fourth and said fifth lens unit is shorter.

A zoom lens comprising, from front to rear, a first lens unit of negative refractive power, a second lens unit of positive refractive power, and a third lens unit of negative refractive power, said second lens unit having a first member 2a, a second member 2b, a third member 2c and a fourth member 2d, totaling four members, wherein the air separations between said four members in said second lens unit are made variable to vary the image magnification, whereby letting the overall refractive powers for the wide angle and telephoto ends of said second lens unit be denoted by f2W and f2T respectively, the following condition is satisfied:

• f2W<f2T.

A zoom lens comprising a front lens group having a first lens unit of negative refractive power, a second lens unit of negative refractive power and a third lens unit of positive refractive power in this order from the object side and whose overall refractive power when in the wide angle end is positive, and a rear lens group having a positive lens unit and a negative lens unit, and including a non-spherical lens surface, wherein when zooming from the wide angle end to the telephoto end, said first lens unit, said second lens unit and said third lens unit axially move in such relation that the overall refractive power of said front lens group is weaker in the telephoto end than in the wide angle end, and said positive lens unit of said rear lens group and said negative lens unit of said rear lens group axially move in such relation that the separation therebetween narrows.