초록 ▼

A focusing method and apparatus which changes the shutter speed and/or the focusing sampling frequency in order to increase the speed at which an image is brought into focus while at the same time, preventing the influence of flicker from artificial light powered by an AC power source. As the focus

A focusing method and apparatus which changes the shutter speed and/or the focusing sampling frequency in order to increase the speed at which an image is brought into focus while at the same time, preventing the influence of flicker from artificial light powered by an AC power source. As the focus evaluation value is based on the brightness of a signal, shutter speeds and frequencies are set in order to avoid the influence of flicker on the focusing process. A shutter speed of 1/100th of a second with a sampling frequency of 60 Hz can be used in environments which are sufficiently bright in order to increase the focusing speed. Also, the focusing sampling frequency may be set to be large when the focus is far from the focusing point in order to quickly bring the image into focus and the sampling frequency subsequently decreases as the focusing position is approached in order to reduce the chances that the focusing position will be passed. Another feature is to record images as the focus position is being approached so that when the in-focus position is passed, there is no need to back up the focusing lens to the in-focus position to obtain the still image as the still image will have been previously recorded. The other frames which have been recorded may then be discarded.

대표청구항 ▼

[ What is claimed as new and is desired to be secured by Letters Patent of the United States is:] [18.] A camera, comprising:a focusing lens;a motor for driving the focusing lens;an image pick-up for recording an image focused by the focusing lens;a focus evaluation value generator which generates f

[ What is claimed as new and is desired to be secured by Letters Patent of the United States is:] [18.] A camera, comprising:a focusing lens;a motor for driving the focusing lens;an image pick-up for recording an image focused by the focusing lens;a focus evaluation value generator which generates focus evaluation values using a brightness component of an image detected by the image pick-up;means for setting a camera focus sampling frequency to a first sampling frequency and setting a camera shutter speed to a first shutter speed;means for determining a first focus evaluation value using a first determined amount of light which has passed through the focusing lens and is detected by the image pick-up;means for calculating an amount to drive the motor in order to focus the focusing lens using the first focus evaluation value;means for changing at least one of the camera focus sampling frequency and the camera shutter speed when the first focus evaluation value is greater than a reference value; andmeans for determining a second focus evaluation value using a second determined amount of light which has passed through the focusing lens and is detected by the image pick-up, after the means for changing has changed said at least one of the camera focus sampling frequency and the camera shutter speed.