Focus system for movie cameras

An optical system comprising:

• lens means for providing an image of an object;
• scanning means for providing first and second scans of the object;
• range sensing means for providing a correlation signal having a major extremum in each scan;
• extremum sensing means for receiving the correlation signal and providing an output signal which changes from a first to a second state only once during the second scan, the change of state being indicative of the occurrence of the major extremum during the second scan;
• relative position sensing means for sensing the positional relationship of the scanning means and the lens means;
• lens drive means for moving the lens means;
• and
• focus control means for controlling the lens drive means to move the lens means in a direction determined by the positional relationship of the scanning means and the lens means when the output signal changes from the first to the second state during the second scan.

In an optical system including primary optical means, an automatic focusing system for positioning the primary optical means, the automatic focusing system comprising:

• spatial image correlation range sensing means for providing a correlation signal having a major extremum indicative of the distance to an object, the spatial image correlation range sensing means including scanning means for providing a plurality of scan cycles, each cycle comprising first and second scans of an image of the object;
• comparison signal means for providing a comparison signal during the second scan which is a function of the amplitude of the major extremum in the correlation signal during the first scan;
• comparing means for comparing the correlation signal with the comparison signal and producing an output signal which changes from a first to a second state only once during the second scan, and the change being indicative of the major extremum during the second scan;
• positioning means for positioning the primary optical means in a direction determined by the relative position of the scanning means and the primary optical means when the output signal changes from the first to the second state during the second scan.

An optical system comprising:

• primary optical means for providing a primary image of an object;
• auxiliary optical means for providing first and second auxiliary images of the object;
• scanning means for providing first and second means of the second auxiliary image;
• range sensing means for producing a correlation signal having a major extremum during each scan indicative of best correspondence of the first and second auxiliary images;
• comparison signal means for providing a comparison signal during the second scan which is a function of the amplitude of the major extremum in the correlation signal during the first scan;
• comparing means for comparing the correlation signal and the comparison signal and producing an output signal which changes from a first to a second state during the second scan only when the correlation signal has a major extremum;
• positioning means for positioning the primary optical as a function of the relative positions of the scanning means and the primary optical means during the second scans when the output signal changes from the first to the second state.

In an optical system including a primary optical means, an automatic focusing system for positioning the primary optical means, the automatic focusing system comprising:

• spatial image correlation range sensing means for providing a correlation signal having a major extremum indicative of the distance to an object, the spatial image correlation range sensing means including scanning means for scanning an image of the object a plurality of scan cycles, each cycle comprising first and second scans;
• extremum sensing means for receiving the correlation signal and producing an output signal having a unique effect when a major extremum occurs during the second scan;
• relative position sensing means for producing a position signal having a first state when the scanning means and the primary optical means have a first positional relationship and having a second state when the scanning means of the primary optical means have a second positional relationship;
• control means for producing a first position correction signal when the position signal changes from the first to the second state and the output signal had its unique effect while the position signal was in the first state, and for producing the second position correction signal when the position signal changes from the first to the second state and the output signal did not have its unique value while the position signal was in the first state;
• and
• position means for positioning the primary optical means in response to the first and second position correction signals.

An optical system comprising:

• primary optical means for providing a primary image of an object;
• auxiliary optical means for providing first and second auxiliary images of the object;
• scanning means for scanning the second auxiliary image with respect to the first auxiliary image a plurality of scanning cycles, each cycle comprising first and second scans;
• range sensing means for producing a correlation signal having a major extremum during each scan indicative of best correspondence of the first and second auxiliary images;
• extremum sensing means for receiving the correlation signal and for producing an output signal which changes from a first to a second state only once during the second scan, the change of state being indicative of the occurrence of the major extremum during the second scan;
• relative position sensing means for producing a position signal having a state when the scanning means and the primary optical means have a first positional relationship and having a second state when the scanning means and the primary optical means have a second positional relationship;
• control means for producing a first position correction signal when the position signal changes from the third to the fourth state and the output signal changed from the first to the second state during the second scan while the position signal was in the third state, and for producing a second position correction signal when the position signal changes from the third to the fourth state and the output signal did not change from the first to the second state during the second scan while the position signal was in the first state;
• and
• positioning means for positioning the primary optical means in response to the first and second position correction signals.