Zoom Lens and Image Pickup Apparatus Using the Same

A zoom lens comprising in order from an object side:

• a first lens unit having a positive refractive power;
• a second lens unit having a negative refractive power;
• and
• a third lens unit having a positive refractive power, wherein
• the third lens unit having a positive refractive power comprises in order from the object side,
• a first lens component having a positive refractive power,
• a second lens component having a negative refractive power in which, a lens having a positive refractive power and a lens having a negative refractive power are cemented, and
• a third lens component, and
• the zoom lens satisfies the following conditional expressions (2a) and (4)
• nd3—2p−nd—2n≧−0.1 (2a)
• Σd3G/ft<0.42 (4)
• where,
• nd3—2p denotes a refractive index for a d-line of the lens having a positive refractive power, in the second lens component having a negative refractive power, in the third lens unit having a positive refractive power, and
• nd3—2n denotes a refractive index for the d-line of the lens having a negative refractive power, in the second lens component having a negative refractive power, in the third lens unit having a positive refractive power,
• Σd3G denotes a total length (not including an aperture) of the third lens unit, and
• ft denotes a focal length at a telephoto end of the overall zoom lens system.

A zoom lens comprising in order from an object side:

• a first lens unit having a positive refractive power;
• a second lens unit having a negative refractive power;
• and
• a third lens unit having a positive refractive power, wherein
• the third lens unit having a positive refractive power comprises in order from the object side,
• a first lens component having a positive refractive power,
• a second lens component having a negative refractive power in which, a lens having a positive refractive power and a lens having a negative refractive power are cemented,
• a third lens component, and
• a fourth lens component, and
• the zoom lens satisfies the following conditional expressions (2b) and (4)
• nd3—2p−nd3—2n≧−0.2 (2b)
• Σd3G/ft<0.42 (4)
• where,
• nd3—2p denotes a refractive index for a d-line of the lens having a positive refractive power, in the second lens component having a negative refractive power, in the third lens unit having a positive refractive power, and
• nd3—2 denotes a refractive index for the d-line of the lens having a negative refractive power, in the second lens component having a negative refractive power, in the third lens unit having a positive refractive power,
• Σd3G denotes a total length (not including an aperture) of the third lens unit, and
• ft denotes a focal length at a telephoto end of the overall zoom lens system.

A zoom lens comprising in order from an object side:

• a first lens unit having a positive refractive power;
• a second lens unit having a negative refractive power;
• and
• a third lens unit having a positive refractive power, wherein
• the third lens unit comprises in order from the object side,
• a first lens component having a positive refractive power, and
• a second lens component having a negative refractive power, and
• the second lens component having a negative refractive power comprises not less than two lenses, and
• the zoom lens satisfies the following conditional expressions (21) and (22)
• 0.06<|d3—12 air/Σd3—12<0.2 (21)
• 2.2<f3/fw<3.7 (22)
• where,
• d3—12 air denotes an air space between the first lens component having a positive refractive power and the second lens component having a negative refractive power, in the third lens unit having a positive refractive power,
• Σd3—12 denotes an optical axial distance from a surface nearest to the object side of the first lens component having a positive refractive power up to a surface nearest to an image side of the second lens component having a negative refractive power, in the third lens unit having a positive refractive power,
• f3 denotes a focal length of the third lens unit, and
• fw denotes a focal length at a wide angle end of the overall zoom lens system.