Automatic focus adjustment apparatus for moving object photography

An automatic focus adjustment apparatus comprising:

• a focus detection device which detects a deviation amount along an optical axis between an object image plane and a prospective focal plane of an objective lens at a predetermined time interval;
• a moving amount detection device which detects a moving amount of said objective lens;
• an image plane speed calculation circuit which calculates a moving speed of the object image plane based on the deviation amount detected by said focus detection device and the moving amount detected by said moving amount detection device;
• a focusing position calculation circuit which calculates a focusing position of said objective lens where the object image plane is caused to coincide with the prospective focal plane based on the deviation amount detected by said focus detection device, the moving amount detected by said moving amount detection device, and the moving speed calculated by said image plane speed calculation circuit;
• a position detection device which detects a current position of said objective lens;
• a position control circuit which controls a position of said objective lens based on a position deviation between the focusing position calculated by said focusing position calculation circuit and the current position detected by said position detection device;
• a speed control circuit which determines a control amount for controlling the moving speed of said objective lens based on a control output from said position control circuit and the moving speed of the object image plane calculated by said image plane speed calculation circuit;
• and
• a driving device which drives said objective lens according to the control amount determined by said speed control circuit.