US 12,386,157 B2
Imaging lens and imaging apparatus
Daiki Kawamura, Saitama (JP); and Michio Cho, Saitama (JP)
Assigned to FUJIFILM Corporation, Tokyo (JP)
Filed by FUJIFILM Corporation, Tokyo (JP)
Filed on Oct. 27, 2023, as Appl. No. 18/496,189.
Application 18/496,189 is a continuation of application No. 17/155,283, filed on Jan. 22, 2021, granted, now 11,841,486.
Claims priority of application No. 2020-012799 (JP), filed on Jan. 29, 2020; and application No. 2020-219164 (JP), filed on Dec. 28, 2020.
Prior Publication US 2024/0077707 A1, Mar. 7, 2024
Int. Cl. G02B 15/14 (2006.01); G02B 15/20 (2006.01); G02B 27/00 (2006.01)
CPC G02B 15/1421 (2019.08) [G02B 15/20 (2013.01); G02B 27/0025 (2013.01)] 10 Claims
OG exemplary drawing
 
1. An imaging lens comprising, as lens groups, only three lens groups consisting of, in order from an object side to an image side: a first lens group that has a positive refractive power; a second lens group that has a refractive power; and a third lens group that has a refractive power,
wherein during focusing from an object at infinity to a closest object, only the second lens group moves along an optical axis,
during focusing, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, and mutual distances between all lenses in the first lens group, mutual distances between all lenses in the second lens group, and mutual distances between all lenses in the third lens group are constant,
the first lens group includes at least two negative lenses,
the number of positive single lenses included in the first lens group is three,
the second lens group includes a negative lens at a position closest to the object side,
a lens surface closest to the image side in the second lens group is concave,
the imaging lens includes, within the lens groups, successively in order from a position closest to the image side to the object side, a first image side lens as a negative single lens of which an object side lens surface is concave, a second image side lens as a biconvex single lens, a third image side lens as a negative lens of which an image side lens surface is concave, a fourth image side lens as a positive lens, and a fifth image side lens as a biconvex single lens,
the number of biconvex single lenses included in the imaging lens is three, including the second image side lens and the fifth image side lens,
a stop is disposed closer to the object side than the fifth image side lens, and closer to the image side than a lens that is second from the object side in the first lens group,
a cemented lens, in which a biconcave lens and a positive lens of which an object side surface is convex are cemented in this order from the object side to the image side, is disposed adjacent to an object side of the stop, and
assuming that:
a sum of a distance on the optical axis from a lens surface closest to the object side to a lens surface closest to the image side and a back focal length at an air-converted distance in a state where the object at infinity is in focus is TL,
an F number of the imaging lens in the state where the object at infinity is in focus is FNo,
a focal length of the imaging lens in the state where the object at infinity is in focus is f, and
a focal length of the second lens group is f2,
Conditional Expressions (5-3) and (12-6) are satisfied, which are represented by
2.685≤TL×FNo/f<5  (5-3), and
0.786≤|f21/f<2.2  (12-6).