Patent ID: 11966030
Assignee: FUJIFILM CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 22:
23. A zoom lens consisting of, in order from an object side to an image side, a first lens group that has a negative refractive power, a middle group, and a final group,
wherein during zooming, a spacing between the first lens group and the middle group changes, and a spacing between the middle group and the final group changes,
during focusing, at least a part of the middle group moves along an optical axis as a focus group, and the first lens group and the final group remain stationary with respect to an image plane,
a back focal length of the zoom lens at an air conversion distance at a wide angle end in a state where an infinite distance object is in focus is Bfw,
a focal length of the zoom lens at the wide angle end in the state where the infinite distance object is in focus is fw,
a maximum half angle of view at the wide angle end in the state where the infinite distance object is in focus is ωw,
Conditional Expression (1) is satisfied, which is represented by

0.35<Bfw/(fw×tan|ωw|)<1.5  (1),

the middle group includes, in order from the object side to the image side, a front subgroup having a positive refractive power and a rear subgroup having a negative refractive power,
an angle formed by the optical axis and a normal line of a lens surface at an effective diameter end of the lens surface is a and a unit of α is degrees, and
the rear subgroup includes one or more lens surfaces as convex surfaces being in contact with air and satisfying Conditional Expression (5), which is represented by

13<|α|<50  (5).