Zoom lens and image pickup apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorYousuke Ookubo
Life of this patent
Estimating the term…
Abstract
A zoom lens includes first to fourth lens units in order from the object side to the image side. The first, third, and fourth lens units have a positive refractive power. The second lens unit has a negative refractive power. Distances between the lens units are changed during zooming. The first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side. The Nd1a and νd1a are a refractive index and an Abbe number, respectively, of a material of the first lens for the d-line and are adequately set.
Claims9
A zoom lens, 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 the first, second, third and fourth lens units are arranged in order from the object side to the image side, respectively,
- wherein distances between the lens units are changed during zooming,
- wherein the first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side, and
- wherein, when Nd1a and νd1a are a refractive index and an Abbe number, respectively, of a material of the first lens for a d-line, the following conditions are satisfied:
- νd1a<23.8
- Nd1a>0.0186×νd1a+1.594
Dependencies are inferred from the claim text.