Zoom lens system and imaging apparatus
AssigneeNittoh Inc.
InventorTetsuya Abe
Life of this patent
Estimating the term…
Abstract
A zoom lens system (10) for imaging, includes, in order from an object side (11); a first lens group (G1) with negative refractive power that moves at the time of zooming; a second lens group (G2) with a positive refractive power that moves at the time of zooming, the second lens group including an aperture stop (St); a third lens group (G3) with a positive refractive power, the position of which is fixed relative to the image plane. The second lens group includes: a first sub-lens group (S1) with a positive refractive power arranged on the object side and having the aperture stop; and a second sub-lens group (S2) with a negative refractive power arranged on the image plane side and configured to move independently of the first sub-lens group at the time of focusing.
Claims15
A zoom lens system for image pickup comprising, in order from the object side:
- a first lens group with negative refractive power that moves during zooming;
- a second lens group with positive refractive power that moves during zooming including an aperture stop;
- and
- a third lens group with positive refractive power, a position of that being fixed with respect to an image plane,
- wherein the first lens group and the second lens group move, when zooming from a wide-angle end to a telephoto end, so as to decrease a distance between the first lens group and the second lens group and increase a distance between the second lens group and the third lens group while the position of the third lens group is fixed,
- a position of the first lens group at the telephoto end is located on the image plane side to a position at the wide-angle end,
- a position of the second lens group at the telephoto end is located on the object side to a position at the wide-angle end, and
- the second lens group includes:
- a first sub-lens group with positive refractive power disposed on the object side including the aperture stop;
- and
- a second sub-lens group with negative refractive power disposed on the image plane side that moves independently of the first sub-lens group during focusing.
A zoom lens system for image pickup comprising, in order from the object side:
- a first lens group with negative refractive power that moves during zooming;
- a second lens group with positive refractive power that moves during zooming including an aperture stop;
- and
- a third lens group with positive refractive power, a position of that being fixed with respect to an image plane,
- wherein the first lens group and the second lens group move, when zooming from a wide-angle end to a telephoto end, so as to decrease a distance between the first lens group and the second lens group and increase a distance between the second lens group and the third lens group while the position of the third lens group is fixed, and
- the second lens group includes:
- a first sub-lens group with positive refractive power disposed on the object side including the aperture stop;
- and
- a second sub-lens group with negative refractive power disposed on the image plane side that moves independently of the first sub-lens group during focusing, and
- the second sub-lens group includes a first lens unit with positive refractive power and a second lens unit with negative refractive power and a focal length fLP of the first lens unit and a focal length fLN of the second lens unit satisfy a following condition:
- 0.25<|fLN/fLP|<0.50.
A zoom lens system for image pickup comprising, in order from the object side:
- a first lens group with negative refractive power that moves during zooming;
- a second lens group with positive refractive power that moves during zooming including an aperture stop;
- and
- a third lens group with positive refractive power, a position of that being fixed with respect to an image plane,
- wherein the first lens group and the second lens group move, when zooming from a wide-angle end to a telephoto end, so as to decrease a distance between the first lens group and the second lens group and increase a distance between the second lens group and the third lens group while the position of the third lens group is fixed, and
- the second lens group includes:
- a first sub-lens group with positive refractive power disposed on the object side including the aperture stop;
- and
- a second sub-lens group with negative refractive power disposed on the image plane side that moves independently of the first sub-lens group during focusing, and
- the first sub-lens group and the second sub-lens group move separately during zooming.
Dependencies are inferred from the claim text.