Zoom lens
AssigneeCanon Kabushiki Kaisha
InventorsAkihisa Horiuchi, Hiroyuki Hamano, Akihiro Nishio, Yasunori Murata
Life of this patent
Estimating the term…
Abstract
A zoom lens includes, from front to rear, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive refractive power and a fourth lens unit of positive refractive power, zooming being performed by moving the second and fourth lens units, and focusing being performed by moving the fourth lens unit, wherein the second lens unit is constructed from three single lenses, i.e., from front to rear, a negative first lens having a strong concave surface facing the image side, a negative second lens of bi-concave form and a positive third lens having a strong convex surface facing the object side.
Claims34
A zoom lens comprising, along an optical axis in order from an object side, at least a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power, said second lens unit comprising, in order from the object side, a negative first lens having a strong concave surface facing an image side, a negative second lens of bi-concave form and a positive third lens having a strong convex surface facing the object side, wherein all of the lenses of said second lens unit are uncemented, and said first lens unit and said third lens unit remain stationary, as zooming is performed by moving said second lens unit and said fourth lens unit along the optical axis.
A zoom lens comprising, along an optical axis, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit having a negative refractive power;
- a third lens unit having a positive refractive power;
- and
- a fourth lens unit having a positive refractive power,
- wherein said second lens unit consists of, in order from the object side, a negative first lens, an air space, a negative second lens, an air space, and a positive third lens, and
- wherein said first lens unit and said third lens unit remain stationary, and
- wherein zooming is performed by moving said second lens unit and said fourth lens unit along the optical axis.
A zoom lens, along an optical axis, in order from an object side, comprising:
- a first lens unit having a positive refractive power;
- a second lens unit having a negative refractive power;
- a third lens unit having a positive refractive power;
- and
- a fourth lens unit having a positive refractive power,
- wherein said second lens unit comprises, in order from the object side, a negative first lens, an air space, a negative second lens, an air space, and a positive third lens, and
- wherein zooming is performed by moving said second lens unit and said fourth lens unit along the optical axis, and focusing is performed by said fourth lens unit.
Dependencies are inferred from the claim text.