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

Claim 6:
7. The imaging lens system according to claim 1,
wherein the fourth sub-group includes an object-side cemented lens made of a negative lens and a positive lens and an image-side cemented lens made of a positive meniscus lens with a convex surface facing the image side and a negative lens, the object-side cemented lens and the image-side cemented lens being disposed in that order from the object side to the image side,
wherein conditional expressions (10), (11), and (12) below are satisfied:

vd22>55  (10);

θgF22>−0.00162×vd22+0.64  (11);, and

1.70<n2P  (12), where
vd22 denotes Abbe number of material of the positive lens of the object-side cemented lens,
θgF22 denotes a partial dispersion ratio with respect to g line of the material of the positive lens of the object-side cemented lens, and
n2P denotes a refractive index of material of the positive meniscus lens of the image-side cemented lens.