Patent attributes
An eyepiece includes, in order from the object side, a first lens with positive power, a second lens with positive power, and a third lens with negative power. The first lens is a positive meniscus lens with a convex surface facing the object side, and the eyepiece fails to have a fourth lens. The eyepiece satisfies the following conditions:0.6<f1/f<1.2−2.0<f1-2/f3<−1.0−0.45<f3/f<−0.25where f1 is the focal length of the first lens; f1-2 is a combined focal length of the first and second lenses and is a focal length where a diopter is −1 m−1 when the focal length of the eyepiece is changed; f3 is the focal length of the third lens; and f is the focal length of the entire system of the eyepiece and is a focal length where a diopter is −1 m−1 when the focal length of the eyepiece is changed.
