The purpose is to provide a large-aperture-ratio internal focusing telephoto lens applicable to a wider photographing area by equipping a vibration reduction function capable to satisfactorily correct a camera shake and the like with securing superb optical performance. The large-aperture-ratio internal focusing telephoto lens includes, in order from an object, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The second lens group G2 is moved along an optical axis upon changing focus from infinity to a close-range object. The first lens group G1 has at least two cemented lenses and satisfies a given conditional expression. Either one of the cemented lens satisfies a given conditional expression.

 
Web www.patentalert.com

< Supercomputing

> Methods to find worst-case setup and hold relationship for static timing analysis

~ 00454