Zoom lens system, imaging device and camera

An imaging device capable of converting an optical image of a photographic object into an electric image signal and then outputting the signal, comprising:

• a zoom lens system that forms the optical image of the photographic object with a variable magnification;
• and
• an image sensor that converts the optical image of the photographic object formed by the zoom lens system into the electric image signal, wherein
• the zoom lens system, in order from the object side serving as the photographic object side to the image side, comprises:
• a first lens unit having negative optical power;
• a second lens unit having positive optical power;
• and a third lens unit having positive optical power,
• in zooming from a wide-angle limit to a telephoto limit, the lens units move respectively along an optical axis in such a manner that an interval between the first lens unit and the second lens unit decreases while an interval between the second lens unit and the third lens unit changes so that the variable magnification is achieved,
• the first lens unit comprises:
• one object side negative lens element with the convex surface facing the object side;
• and one image side positive lens element with the convex surface facing the object side that is arranged with an air space on the image side of the object side negative lens element,
• each of the two lens elements constituting the first lens unit has an aspheric surface, and
• the following conditions (1), (2) and (3) are satisfied:
• n12>1.88 (1)
• v12<26 (2)
• 5.0<αiW<20.0 (3)
• (where, ωW≧33.97)
• in which,
• n12 is a refractive index of the image side positive lens element of the first lens unit,
• v12 is an Abbe number of the image side positive lens element of the first lens unit,
• αiW is an incident angle of the principal ray onto the image sensor at the maximum image height at a wide-angle limit (here, the incident angle is defined as positive when the principal ray is incident on the light receiving surface of the image sensor with departing from the optical axis), and
• ωW is a half view angle at a wide-angle limit.

A camera capable of shooting a photographic object and then outputting its image as an electric image signal, comprising:

• an imaging device including a zoom lens system that forms the optical image of the photographic object with a variable magnification, and an image sensor that converts the optical image of the photographic object formed by the zoom lens system into the electric image signal, wherein
• the zoom lens system, in order from the object side serving as the photographic object side to the image side, comprises:
• a first lens unit having negative optical power;
• a second lens unit having positive optical power;
• and a third lens unit having positive optical power,
• in zooming from a wide-angle limit to a telephoto limit, the lens units move respectively along an optical axis in such a manner that an interval between the first lens unit and the second lens unit decreases while an interval between the second lens unit and the third lens unit changes so that the variable magnification is achieved,
• the first lens unit comprises:
• one object side negative lens element with the convex surface facing the object side;
• and one image side positive lens element with the convex surface facing the object side that is arranged with an air space on the image side of the object side negative lens element,
• each of the two lens elements constituting the first lens unit has an aspheric surface, and
• the following conditions (1), (2) and (3) are satisfied:
• n12>1.88 (1)
• v12<26 (2)
• 5.0<αiW<20.0 (3)
• (where, ωW≧33.97)
• in which,
• n12 is a refractive index of the image side positive lens element of the first lens unit,
• v12 is an Abbe number of the image side positive lens element of the first lens unit,
• αiW is an incident angle of the principal ray onto the image sensor at the maximum image height at a wide-angle limit (here, the incident angle is defined as positive when the principal ray is incident on the light receiving surface of the image sensor with departing from the optical axis), and
• ωW is a half view angle at a wide-angle limit.