Zoom lens system and image pickup apparatus including the same

A zoom lens system having an optical axis and object and image sides, comprising:

• a first lens unit of negative optical power;
• a second lens unit of positive optical power, the second lens unit being disposed on the image side of the first lens unit,
• wherein the second lens unit includes a lens element disposed closest to the object side, the lens element including:
• a rim;
• a surface on the object side and having a vertex;
• and
• an intersection point defined by an intersection between the surface and the rim;
• a third lens unit of positive optical power, the third lens unit being disposed on the image side of the second lens unit;
• and
• an aperture stop determining an effective aperture diameter of the lens system, the position of the aperture stop along the optical axis being between the vertex and the intersection point and being a negative distance with respect to the vertex, indicating that the position of the aperture stop is on the image side of the vertex,
• wherein the first to third lens units are provided in order from the object side to the image side such that there is no lens unit between the second lens unit and the third lens unit,
• wherein spaces between the first, second and third lens units vary during zooming, and
• wherein a distance between a vertex on the object side of a lens element of the first lens unit that is closest to the object side and the vertex on the image side of the lens element of the first lens unit that is closest to the image side (DL1), a distance between a vertex on the object side of the lens element of the second lens unit that is closest to the object side and a vertex on the image side of the lens element of the second lens unit that is closest to the image side (DL2), a distance between a vertex on the object side of a lens element of the third lens unit that is closest to the object side and a vertex on the image side of the lens element of the third lens unit that is closest to the image side (DL3), and a focal length at the wide-angle end of the entire zoom lens system (fw) satisfy the following condition:
• 1.3<(DL1+DL2+DL3)/fw<2.0.

A zoom lens system having an optical axis and object and image sides, comprising:

• a first lens unit of negative optical power;
• a second lens unit of positive optical power, the second lens unit being disposed on the image side of the first lens unit,
• wherein the second lens unit includes a lens element disposed closest to the object side, the lens element including:
• a rim;
• a surface on the object side and having a vertex;
• and
• an intersection point defined by an intersection between the surface and the rim;
• a third lens unit of positive optical power, the third lens unit being disposed on the image side of the second lens unit;
• and
• an aperture stop determining an effective aperture diameter of the lens system, the position of the aperture stop along the optical axis being between the vertex and the intersection point and being a negative distance with respect to the vertex, indicating that the position of the aperture stop is on the image side of the vertex,
• wherein the first to third lens units are provided in order from the object side to the image side such that there is no lens unit between the second lens unit and the third lens unit,
• wherein spaces between the first, second and third lens units vary during zooming, and
• wherein a distance along the optical axis between the vertex to the object and the aperture stop (D2S), and a distance along the optical axis between the vertex to the object and the intersection point (D2R) satisfy the following condition:
• 0.2<D2S/D2R<0.9.

A zoom lens system having an optical axis and object and image sides, comprising:

• a first lens unit of negative optical power;
• a second lens unit of positive optical power, the second lens unit being disposed on the image side of the first lens unit,
• wherein the second lens unit includes a lens element disposed closest to the object side, the lens element including:
• a rim;
• a surface on the object side and having a vertex;
• and
• an intersection point defined by an intersection between the surface and the rim;
• a third lens unit of positive optical power, the third lens unit being disposed on the image side of the second lens unit;
• and
• an aperture stop determining an effective aperture diameter of the lens system, the position of the aperture stop along the optical axis being between the vertex and the intersection point and being a negative distance with respect to the vertex, indicating that the position of the aperture stop is on the image side of the vertex,
• wherein the first to third lens units are provided in order from the object side to the image side such that there is no lens unit between the second lens unit and the third lens unit,
• wherein spaces between the first, second and third lens units vary during zooming, and
• wherein a focal length of the second lens unit (f2), and a focal length at the wide-angle end of the entire zoom lens system (fw) satisfy the following condition:
• 1.2<f2/fw<2.0.