Zoom Lens and Image Pickup Apparatus Using the Same

A zoom lens comprising in order from an object side to an image 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 negative refractive power, wherein
• the zoom lens further includes
• an aperture stop which is disposed between the second lens unit and the fourth lens unit, and
• the first lens unit includes a negative lens and a plurality of positive lenses, and
• at the time of zooming from a wide angle end to a telephoto end,
• a distance between the first lens unit and the second lens unit widens,
• a distance between the second lens unit and the third lens unit narrows, and
• a distance between the third lens unit and the fourth lens unit changes, and
• the following conditional expressions (1) and (3) are satisfied
• 2.85<ft/DG1ASt<7.40 (1)
• 0.16<DG2G3wDG1IMt<0.6 (3)
• where,
• ft denotes a focal length of the overall zoom lens system at the telephoto end,
• DG1ASt denotes a distance on an optical axis from an object-side surface of a lens nearest to the object side in the first lens unit up to the aperture stop, at the telephoto end,
• DG2G3w denotes a distance on the optical axis between the second lens unit and the third lens unit at the wide angle end, and
• DG1IMt denotes a distance on the optical axis from the object-side surface of the lens nearest to the object side in the first lens unit up to an image, at the telephoto end.

A zoom lens comprising in order from an object side to an image 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 negative refractive power;
• wherein
• the zoom lens further includes
• an aperture stop which is disposed between the second lens unit and the fourth lens unit, and
• the first lens unit includes a negative lens and a plurality of positive lenses, and
• at the time of zooming from a wide angle end to a telephoto end,
• a distance between the first lens unit and the second lens unit widens,
• a distance between the second lens unit and the third lens unit narrows, and
• a distance between the third lens unit and the fourth lens unit changes, and
• the following conditional expressions (1) and (4) are satisfied
• 2.85<ft/DG1ASt<7.40 (1)
• 0.05<(DG1IMt−DG1IMw)/ft<0.22 (4)
• where,
• ft denotes a focal length of the overall zoom lens system at the telephoto end,
• DG1ASt denotes a distance on an optical axis from an object-side surface of a lens nearest to the object side in the first lens unit up to the aperture stop, at the telephoto end,
• DG1IMt denotes a distance on the optical axis from an object-side surface of the lens nearest to the object side in the first lens unit up to an image, at the telephoto end,
• DG1IMw denotes a distance on the optical axis (optical axial distance) from the object-side surface of the lens nearest to the object side in the first lens unit up to the image, at the wide angle end.

A zoom lens comprising in order from an object side to an image 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 negative refractive power, wherein
• the zoom lens further includes
• an image-side lens unit having a positive refractive power, which is disposed on the image side of the fourth lens unit, and
• an aperture stop which is disposed between the second lens unit and the fourth lens unit, and
• the first lens unit includes a negative lens and a plurality of positive lenses, and
• at the time of zooming from a wide angle end to a telephoto end,
• a distance between the first lens unit and the second lens unit widens,
• a distance between the second lens unit and the third lens unit narrows,
• a distance between the third lens unit and the fourth lens unit changes, and
• a distance between the fourth lens unit and the image-side lens unit changes, and
• the first lens unit is positioned on the object side at the telephoto end, than a position at the wide angle end, and
• the image-side lens unit is positioned on the image side at the telephoto end, than a position at the wide angle end, and
• the following conditional expression (1) is satisfied
• 2.85<ft/DG1ASt<7.40 (1)
• where,
• ft denotes a focal length of the overall zoom lens system at the telephoto end, and
• DG1ASt denotes a distance on an optical axis from an object-side surface of a lens nearest to the object side in the first lens unit up to the aperture stop, at the telephoto end.

A zoom lens comprising in order from an object side to an image 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 negative refractive power, wherein
• the zoom lens further includes
• an aperture stop which is disposed between the second lens unit and the fourth lens unit, and
• the first lens unit includes a negative lens and a plurality of positive lenses, and
• at the time of zooming from a wide angle end to a telephoto end,
• a distance between the first lens unit and the second lens unit widens,
• a distance between the second lens unit and the third lens unit narrows, and
• a distance between the third lens unit and the fourth lens unit changes, and
• the following conditional expressions (1) and (5) are satisfied
• 2.85<ft/DG1ASt<7.40 (1)
• 20<ft/fw<50 (5)
• where,
• ft denotes a focal length of the overall zoom lens system at the telephoto end,
• DG1ASt denotes a distance on an optical axis from an object-side surface of a lens nearest to the object side in the first lens unit up to the aperture stop, at the telephoto end, and
• fw denotes a focal length of the overall zoom lens system at the wide angle end.