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;
• a third lens unit having a positive refractive power;
• and
• a fourth lens unit having a positive refractive power, wherein
• at the time of zooming, the first lens unit moves, and
• the first lens unit includes in order from the object side, a first lens having a negative refractive power, and a second lens having a positive refractive power, and
• the zoom lens satisfies the following conditional expressions (1-1b) and (1-2b)
• 0.2<(β2T/β2W)/(β3T/β3W)<0.8 (1-1b)
• 0<(Δ1G/f1)/(Δ4G/f4)<1.5 (1-2b)
• where,
• β2W denotes a lateral magnification at a wide angle end of the second lens unit,
• β2T denotes a lateral magnification at a telephoto end of the second lens unit,
• β3W denotes a lateral magnification at a wide angle end of the third lens unit,
• β3T denotes a lateral magnification at a telephoto end of the third lens unit,
• Δ1G denotes an amount of movement of the first lens unit at the time of zooming from the wide angle end to the telephoto end,
• Δ4G denotes an amount of movement of the fourth lens unit at the time of zooming from the wide angle end to the telephoto end,
• f1 denotes a focal length of the first lens unit, and
• f4 denotes a focal length of the fourth lens unit.

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, a first lens component having a positive refractive power and a second lens component having a negative refractive power,
• the zoom lens satisfies the following conditional expressions (2-1), (2-2), and (2-3)
• 2<|f3—2/f3—1|<5 (2-1)
• 0.1<(β2T/β2W)/(β3T/β3W)<0.8 (2-2)
• Fno(W)<2.5 (2-3)
• where,
• f3—1 denotes a focal length of the first lens component in the third lens unit,
• f3—2 denotes a focal length of the second lens component in the third lens unit,
• β2W denotes a lateral magnification at a wide angle end of the second lens unit,
• β2T denotes a lateral magnification at a telephoto end of the second lens unit,
• β3W denotes a lateral magnification at a wide angle end of the third lens unit,
• β3T denotes a lateral magnification at a telephoto end of the third lens unit,
• Δ1G denotes an amount of movement of the first lens unit at the time of zooming from the wide angle end to the telephoto end,
• Δ4G denotes an amount of movement of the fourth lens unit at the time of zooming from the wide angle end to the telephoto end, and
• Fno (W) denotes F number at a wide angle end.

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 first lens unit includes in order from the object side, a first lens having a negative refractive power, and a second lens having a positive refractive power, and
• the third lens unit includes in order from the object side, a first lens component having a positive refractive power, a second lens component having a negative refractive power, and a third lens component, and
• the zoom lens satisfies the following conditional expressions (3-1), (3-2), and (3-3)
• 1.3<|f3—2/f3—1|<5 (3-1)
• Σd3G/fT<0.42 (3-2)
• Fno(W)<2.5 (3-3)
• where,
• f3—1 denotes a focal length of the first lens component having a positive refractive power in the third lens unit,
• f3—2 denotes a focal length of the second lens component having a negative refractive power in the third lens unit,
• Σd3G denotes a total length of the third lens unit,
• fT denotes a focal length of the overall zoom lens system at the telephoto end, and
• Fno(W) denotes an F-number of the zoom lens at the wide angle end.