Zoom lens system, imaging optical device, and digital appliance
AssigneeKonica Minolta Advanced Layers, Inc.
InventorsYoshihito Souma, Yasushi Yamamoto
Life of this patent
Estimating the term…
Abstract
A zoom lens system is composed of negative, positive, negative, and positive lens groups, of which at least the first to third move during zooming. During zooming from the wide-angle end to the telephoto end, the distance between the first and second lens groups decreases, the distance between the second and third lens groups varies, and the distance between the third and fourth lens groups increases. The conditional formulae 1.0≦|f2/f1|≦1.5 and 2.0≦|f4/f1|≦5.0 are fulfilled (f1, f2, and f4 representing the focal lengths of the first, second, and fourth lens groups).
Claims20
A zoom lens system comprising, from an object side, a first lens group having a negative optical power, a second lens group having a positive optical power, a third lens group having a negative optical power, and a fourth lens group having a positive optical power, the zoom lens system achieving zooming by varying distances between the lens groups, wherein
- during zooming, at least the first to third lens groups move individually,
- during zooming from a wide-angle end to a telephoto end, the distance between the first and second lens groups decreases, the distance between the second and third lens groups varies, and the distance between the third and fourth lens groups increases, and
- Conditional Formulae (1) and (2) below are fulfilled:
- 1.0≦|f2/f1|≦1.5 (1)
- 2.0≦|f4/f1|≦5.0 (2)
- where
- f1 represents a focal length of the first lens group;
- f2 represents a focal length of the second lens group;
- and
- f4 represents a focal length of the fourth lens group.
An imaging optical device comprising an image sensor for converting an optical image formed on a light-sensing surface into an electrical signal and a zoom lens system provided such that an optical image of a subject is formed on a light-sensing surface of the image sensor, wherein
- the zoom lens system comprises, from an object side, a first lens group having a negative optical power, a second lens group having a positive optical power, a third lens group having a negative optical power, and a fourth lens group having a positive optical power, the zoom lens system achieving zooming by varying distances between the lens groups, wherein during zooming, at least the first to third lens groups move individually;
- during zooming from a wide-angle end to a telephoto end, the distance between the first and second lens groups decreases, the distance between the second and third lens groups varies, and the distance between the third and fourth lens groups increases;
- and Conditional Formulae (1) and (2) below are fulfilled:
- 1.0≦|f2/f1|≦1.5 (1)
- 2.0≦|f4/f1|≦5.0 (2)
- where
- f1 represents a focal length of the first lens group;
- f2 represents a focal length of the second lens group;
- and
- f4 represents a focal length of the fourth lens group.
A digital appliance comprising an imaging optical device so as to be additionally equipped with at least one of a function of shooting a still image of a subject and a function of shooting a moving image of a subject, wherein
- the imaging optical device comprises:
- an image sensor for converting an optical image formed on a light-sensing surface into an electrical signal;
- and
- a zoom lens system provided such that an optical image of a subject is formed on a light-sensing surface of the image sensor,
- the zoom lens system comprises, from an object side, a first lens group having a negative optical power, a second lens group having a positive optical power, a third lens group having a negative optical power, and a fourth lens group having a positive optical power, the zoom lens system achieving zooming by varying distances between the lens groups, wherein during zooming, at least the first to third lens groups move individually;
- during zooming from a wide-angle end to a telephoto end, the distance between the first and second lens groups decreases, the distance between the second and third lens groups varies, and the distance between the third and fourth lens groups increases;
- and Conditional Formulae (1) and (2) below are fulfilled:
- 1.0≦|f2/f1|≦1.5 (1)
- 2.0≦|f4/f1|≦5.0 (2)
- where
- f1 represents a focal length of the first lens group;
- f2 represents a focal length of the second lens group;
- and
- f4 represents a focal length of the fourth lens group.
Dependencies are inferred from the claim text.