Autofocus strobe control in image sensing apparatus

An image sensing apparatus comprising:

• an image sensing device that senses an optical image of an object and converts the optical image into an image signal to be used for photographing;
• a signal forming device that forms a signal used for focusing on the basis of the image signal obtained from said image sensing device;
• and
• a control device, for each vertical scanning period, that repeatedly emits light for assisting signal forming operation performed by said signal forming device for a light-emission time period that is within and in accordance with a charge accumulation time of said image sensing device in each vertical scanning period,
• wherein said control device emits the light in synchronization with image sensing operation of said image sensing device.

An image sensing apparatus comprising:

• an image sensing device that senses an optical image of an object and converts the optical image into an image signal to be used for photographing;
• a signal forming device that forms a signal used for focusing on the basis of the image signal obtained from said image sensing device;
• and
• a control device, for each vertical scanning period, that repeatedly emits light for assisting signal forming operation performed by said signal forming device for a light-emission time period that is within and in accordance with a charge accumulation time of said image sensing device in each vertical scanning period,
• wherein said control device changes emitting the light in correspondence with a charge accumulation time of said image sensing device when said signal forming device forms the signal for focusing.

A control method of an image sensing apparatus having:

• an image sensing device that senses an optical image of an object and converts the optical image into an image signal to be used for photographing;
• and a signal forming device that forms a signal used for focusing on the basis of the image signal obtained from said image sensing device, said method comprising the steps of:
• emitting light once each vertical scanning period for assisting signal forming operation performed by said signal forming device;
• and
• changing a light-emission time period in each vertical scanning period within and in accordance with a charge accumulation time of said image sensing device when said signal forming device forms the signal for focusing.

An image sensing apparatus capable of sensing an image using a fill-in light emission unit, comprising

• an image sensing unit that obtains an image signal by photoelectric-converting an optical image of an object;
• a determination unit that determines a light-emission time period of said fill-in light;
• a controller that controls said fill-in light emission unit to emit light for the light-emission time period determined by said determination unit in synchronization with start of charge accumulation time;
• and
• focus control unit that performs focus control on the basis of the image signal obtained from said image sensing unit,
• wherein light is emitted for the light-emission time period once each vertical scanning period.