Observation telescope

A telescope optics for a telescopic observational instrument having an objective lens system, having a prism erecting system and having an eyepiece lens system, wherein an image of an object generated by the objective lens system is located between the prism erecting system and the eyepiece lens system, and wherein the objective lens system, in an order starting from an object side, comprises a first lens group G1 with a positive refractive power, a second lens group G2 with a negative refractive power and a third lens group G3 with at least one lens having a negative refractive power, and wherein the second lens group G2 is adjustable in parallel to an optical axis for focusing, and wherein at least one lens with a negative refractive power of the third lens group G3 is adjustable perpendicularly to the optical axis for changing the position of the image, wherein the third lens group G3 has a negative refractive power, wherein the value of a ratio of a specific lateral displacement of the at least one lens with a negative refractive power of the third lens group G3 for image stabilization to a focal length of the third lens group G3 is in a range of between −52×10−3/° and −25×10−3/°, wherein the specific lateral displacement of the at least one lens with a negative refractive power of the third lens group G3 for image stabilization is defined by the lateral displacement of the at least one lens with a negative refractive power of the third lens group G3 required to achieve an image stabilization in case of a tilt of the optical axis about an angle of one degree.