Patent ID: 11934036
Assignee: RICOH COMPANY, LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An imaging lens system comprising:
a first group having positive power group, the first group including two or more positive lenses and three or more negative lenses; and
a second group having positive power,
the first group and the second group being disposed in that order from an object side to an image side of the imaging lens system,
the first group including a first sub-group and a second sub-group adjacent to the first sub-group on the image side, the first sub-group including a lens closest to the object side at one end of the first sub-group and a negative lens component closest to the object side at another end of the first sub-group,
the second group including a third sub-group, a stop, and a fourth sub-group disposed in that order from the object side to the image side,
the second group being configured to be movable to the object side with a change in a distance between the first group and the second group during a change in a focus of the imaging lens system from infinity to close range, and
conditional expressions (1) and (2) below are satisfied:

0.07<f2/f1<0.4  (1);, and

0.45<f2/f2a<0.7  (2), where
f1 denotes a focal length of the first group,
f2 denotes a focal length of the second group, and
f2a denotes a focal length of the third sub-group.