Zoom lens and imaging apparatus
AssigneeFUJIFILM Corporation
InventorUkyo Tomioka
Life of this patent
Estimating the term…
Abstract
The zoom lens includes, in order from an object side, a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, a diaphragm, and a fourth lens group G4. During zooming, only the second lens group G2 and the third lens group G3 move. The first lens group G1 includes, in order from the object side, a cemented lens that is formed by cementing a positive lens and a negative meniscus lens convex toward the object side, a positive lens, and a negative lens. A conditional expression (1): −0.8<f1a/f1b<0 is satisfied, where f1a is a composite focal length of the first to third lenses from the object side of the first lens group G1, and f1b is a focal length of the fourth lens.
Claims20
A zoom lens consisting of, in order from an object side:
- a first lens group that has a positive refractive power;
- a second lens group that has a negative refractive power;
- a third lens group that has a positive refractive power;
- a diaphragm;
- and
- a fourth lens group,
- wherein during zooming, the first lens group and the fourth lens group remain stationary with respect to an image plane, and the second lens group and the third lens group move so as to have a different relative spacing therebetween in an optical axis direction,
- wherein the first lens group consists of, in order from the object side, a cemented lens that is formed by cementing a first lens, which has a negative refractive power and has a meniscus shape convex toward the object side, and a second lens which has a positive refractive power, a third lens that has a positive refractive power, and a fourth lens that has a negative refractive power,
- wherein the following conditional expression (1) is satisfied,
- −0.8<f1a/f1b<0 (1),
- where f1a is a composite focal length of the first lens, the second lens, and the third lens, and
- f1b is a focal length of the fourth lens, and
- wherein lens spacing in the fourth lens group does not change during zooming.
Dependencies are inferred from the claim text.