Large-aperture telephoto lens system
AssigneeRicoh Imaging Company, Ltd.
InventorTatsuyuki Onozaki
Life of this patent
Estimating the term…
Abstract
A large-aperture telephoto lens system includes a positive first lens group, a negative second lens group, and a positive third lens group, in that order from the object side, wherein the second lens group serves as a focusing lens group which is moved during focusing on an object at infinity to an object at a finite distance, wherein the following conditions (1) and (2) are satisfied: −4<f/f2<−3 (1), and 1.3<f/f3<2.3 (2), wherein f designates the focal length of the entire large-aperture telephoto lens system, f2 designates the focal length of the second lens group, and f3 designates the focal length of the third lens group.
Claims14
A large-aperture telephoto lens system comprising a positive first lens group, a negative second lens group, and a positive third lens group, in that order from the object side, wherein said second lens group serves as a focusing lens group which is moved in an optical axis direction during a focusing operation on an object at infinity to an object at a finite distance,
- wherein the following conditions (1) and (2) are satisfied:
- −4<f/f2<−3 (1), and
- 1.3<f/f3<2.3 (2), wherein
- f designates the focal length of the entire large-aperture telephoto lens system,
- f2 designates the focal length of said second lens group, and
- f3 designates the focal length of said third lens group, and
- wherein said third lens group consists of a cemented lens provided with one negative lens element and one positive lens element.
A large-aperture telephoto lens system comprising a positive first lens group, a negative second lens group, and a positive third lens group, in that order from the object side, wherein said second lens group serves as a focusing lens group which is moved in an optical axis direction during a focusing operation on an object at infinity to an object at a finite distance,
- wherein said first lens group includes a positive lens element having a convex surface on the object side, a positive meniscus lens element having a convex surface on the object side, a positive meniscus lens element having a convex surface on the object side, a negative lens element, a negative lens element having a convex surface on the object side, and a positive lens element having a convex surface on the object side, in that order from the object side.
Dependencies are inferred from the claim text.