Zoom lens system

A zoom lens system comprising a negative first lens group, a positive second lens group, and a positive third lens group, in this order from an object,

• wherein upon zooming from the short focal length extremity to the long focal length extremity, the distance between said negative first lens group and said positive second lens group decreases, and the distance between said positive second lens group and said positive third lens group increases,
• wherein the most image-side lens element of said positive second lens group comprises a meniscus lens element having the concave surface facing toward an image;
• and
• wherein said meniscus lens element satisfies the following condition:
• 0.4<|Rs|/fw<0.8
• wherein
• Rs designates the radius of curvature of the image-side surface of said meniscus lens element.

A zoom lens system comprising a negative first lens group, a positive second lens group, and a positive third lens group, in this order from an object,

• wherein upon zooming from the short focal length extremity to the long focal length extremity, the distance between said negative first lens group and said positive second lens group decreases, and the distance between said positive second lens group and said positive third lens group increases;
• wherein said positive second lens group comprises a single positive lens element, and a single negative lens element or cemented lens elements which as a whole have a negative refractive power;
• and
• wherein said single positive lens element is provided with an aspherical surface on each surfaces thereof, and satisfies the following conditions:
• 0.6<|ΔIR1/IR1|<1.4 (ΔIR1/IR1<0) 0.6<|ΔIR2/IR2|<1.4 (ΔIR2/IR2<0)
• wherein
• ΔIR1 designates the amount of change of the third-order spherical aberration coefficient due to the object-side aspherical surface of said single positive lens element with said aspherical surfaces under the condition that the focal length at the long focal length extremity is converted to 1.0;
• IR1 designates the third-order spherical aberration coefficient due to the object-side paraxial spherical component of said single positive lens element with the aspherical surfaces when the focal length at the long focal length extremity is converted to 1.0;
• ΔIR2 designates the amount of change of the third-order spherical aberration coefficient due to the image-side aspherical surface of said single positive lens element with said aspherical surfaces under the condition that the focal length at the long focal length extremity is converted to 1.0;
• and
• IR2 designates the third-order spherical aberration coefficient due to the image-side paraxial spherical component of said single positive lens element with the aspherical surfaces when the focal length at the long focal length extremity is converted to 1.0.

A zoom lens system comprising a negative first lens group, a positive second lens group, and a positive third lens group, in this order from and object,

• wherein upon zooming from the short focal length extremity to the long focal length extremity, the distance between said negative first lens group and said positive second lens group decreases, and the distance between the positive second lens group and the positive third lens group increases;
• wherein said positive second lens group comprises a single positive lens element, and a single negative lens element or cemented lens elements which as a whole have a negative refractive power;
• wherein said single positive lens element is provided with an aspherical surfaces on each surface thereof;
• and
• wherein said zoom lens system satisfies the following condition:
• 0.3<LD2G/LD3G−im<1.2
• wherein
• LD2G designates the distance along the optical axis from the most object-side surface of said positive second lens group to the most image-side surface thereof;
• and
• LD3G−im designates the minimum distance along the optical axis from the most object-side surface of said positive third lens group to the image plane over the entire zooming range.