Patent ID: 6927376

Claim:
A method for autofocusing an optical instrument, in particular a telescopes along an optical axis, said optical instrument having a focusing member and image sensors resolve the image signal into pixels, such as CCD lines and/or matrices as well as CMOS image sensors, characterized in that, on the basis of said pixel that is located closest to said optical axis, the local signal amplitude is calculated from the monotonically decreasing or increasing signal all the way to the next local maximum and minimum, as long as this local signal amplitude is considerably smaller than the maximum signal and said focusing member of the telescope lens is in the focusing position for short focusing distances, this focusing member is shifted in large increments, depending on the magnitude of the local signal amplitude, the focusing distance is shortened in the area of greater focusing distances in relation to the maximum signal and to the position of said focusing member, at a certain magnitude of the local signal amplitude in relation to the maximum signal, the cross correlation functions (CCF) are each additionally formed from several pixels of the signal and from suitable comparison structures, at a certain ratio of a reference function formed on the basis of the CCD to the local signal amplitude, an increment range that is comparable to the optical depth of field is selected and focused to the maximum of the CCF.