| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic focusing(AF) device for business or professional video camera capable of being accurately operated with respect to an object having saturated luminance by extracting the high-frequency component of the specified area of an image signal, generating an evaluation value and enlarging and changing the specified area when a value obtained by adding the saturated luminance is equal to over a prescribed value in the specified area extending over a prescribed time. SOLUTION: An AF block 137 is provided with an AF-IC 139 and a CPU for AF 138 and constituted so that the high-frequency component of the specified area of the image signal is extracted and the evaluation value is generated. Besides, a command value given to the focusing lens 111 of the video camera is calculated according to the evaluation value and transmitted to a focusing lens driving circuit 11c. Then, the value obtained by adding the saturated luminance is calculated by counting the number of times that the luminance becomes over the first prescribed value in the specified area. When the value obtained by adding the saturated luminance becomes over the second prescribed value extending over the prescribed time in the midst of an action for searching the peak of the evaluation value, the specified area is extended and changed. |
