Mount conversion adaptor lens
AssigneeFuji Photo Optical Co., Ltd.
InventorKatsuhisa Tsutsumi
Life of this patent
Estimating the term…
Abstract
An adaptor lens is provided for attachment between a lens of a camera and a camera body, in order to provide the camera with adaptor lens attached, a smaller effective screen size than the camera without the adaptor lens attached. The adaptor lens is formed of, in order from the object side, a front lens group and a rear lens group. The front lens group is formed of, in sequential order from the object side, a negative lens element and at least one meniscus lens element with its concave surface on the object side. The rear lens group is formed of, in sequential order from the object side, a positive lens element with a convex surface on the object side, and a negative lens element. Various conditions are, preferably, satisfied in order to maintain favorable correction of axial chromatic aberration and lateral color.
Claims7
An adaptor lens, for attachment between a lens of a camera and a camera body, in order to provide the camera, with adaptor lens attached, a smaller effective screen size than the camera without the adaptor lens attached, said adaptor lens formed of, in order from the object side:
- a front lens group;
- and
- a rear lens group;
- wherein
- the front lens group is formed of, in sequential order from the object side without any intervening lens element, a negative lens element and at least one meniscus lens element with its concave surface on the object side;
- and
- the rear lens group is formed of, in sequential order from the object side, a positive lens element with a convex surface on the object side, and a negative lens element.
An adaptor lens, for attachment between a lens of a camera and a camera body, in order to provide the camera, with adaptor lens attached, a smaller effective screen size than the camera without the adaptor lens attached, said adaptor lens is formed of, in order from the object side:
- a front lens group;
- and
- a rear lens group;
- wherein
- the front lens group is formed of, in sequential order from the object side, a negative lens element and at least one meniscus lens element with its concave surface on the object side;
- the rear lens group is formed of, in sequential order from the object side, a positive lens element with a convex surface on the object side, and a negative lens element;
- and
- the following condition is satisfied
- 0.5≦|fLA1/f|≦1.4
- where
- fLA1 is the focal length of the first lens element of the first lens group of the adaptor lens, in order from the object side, and
- f is the focal length of the adaptor lens.
An adaptor lens, for attachment between a lens of a camera and a camera body, in order to provide the camera, with adaptor lens attached, a smaller effective screen size than the camera without the adaptor lens attached, said adaptor lens formed of, in order from the object side:
- a front lens group;
- and
- a rear lens group;
- wherein
- the front lens group is formed of, in sequential order from the object side, a negative lens element and at least one meniscus lens element with its concave surface on the object side;
- the rear lens group is formed of, in sequential order from the object side, a positive lens element with a convex surface on the object side, and a negative lens element;
- and
- the following condition is satisfied
- 0.1≦|fLA4/fLA5|≦0.7
- where
- fLA4 is the focal length of the fourth lens element of the adaptor lens, in order from the object side, and
- fLA5 is the focal length of the fifth lens element of the adaptor lens, in order from the object side.
Dependencies are inferred from the claim text.