Patent ID: 8363152

Claim:
A method for focusing a shooting lens of a motion picture or video camera onto a moving or stationary object said shooting lens being fastened to the camera at a known distance from a shooting plane of the camera, wherein a principal optical point of the shooting lens being determined by a known distance of the shooting lens from the shooting plane of the camera and by optical data and an actual focus value of the shooting lens, the method comprising: imaging said object on a monitor of a display instrument with a distance measurement instrument which is connected to the camera in a predetermined position, wherein a measurement or reference point of the distance measurement instrument has a known distance from the shooting plane of the camera, said distance measurement instrument being aligned or tracked in relation to a predetermined alignment of the distance measurement instrument with the object as a function of an image angle of an imaging lens of the display instrument and coordinates of the image of the object on the monitor of the display instrument; calculating horizontal and vertical angle deviations of the object from the camera from the coordinates of the image of the object on the monitor; determining a straight line, on which the object to be focused lies, from the horizontal and vertical angle deviations of the object from the camera and the image angle of the imaging lens of the display instrument, said distance measurement instrument being panned on a plane spanned by the straight line and the position of the measurement or reference point of the distance measurement instrument for carrying out distance measurements until the object to be focused is found, determining the focus to be adjusted on the shooting lens based on the distance of the shooting plane of the camera from the principal optical point of the shooting lens, a distance of the principal optical point of the shooting lens from the object to be focused, wherein the distance of the principal optical point of the shooting lens from the object to be focused is determined from the equation D=|D|=|A+C−B| wherein, D is a vector directed from the principal optical point of the shooting lens to the object to be focused, and |D| is the magnitude of vector D, A is a vector directed from the shooting plane of the camera to a measurement point of the distance measurement instrument, B is a vector directed from the shooting plane of the camera to the principal optical point of the shooting lens, and C is a vector directed from the measurement point of the distance measurement instrument to the object to be focused, whereby parallax errors are excluded from said determination of said focus to be adjusted, wherein the length of the vector directed from the shooting plane of the camera to the principal optical point of the shooting lens is determined from the data and the actual focusing value of the shooting lens.