Patent ID: 8792045

Claim:
A method of refocusing a video surveillance camera comprising: performing a first auto-focus operation of a camera at a first time; sensing a first temperature of the camera at the first time; sensing a second temperature of the camera at a second time; determining if a change in temperature between the first temperature and the second temperature is greater than a predetermined temperature change; sensing a level of light in a field of view of the camera at the second time; determining if the level of light sensed in the field of view of the camera at the second time is within a predetermined light level range; determining if a period of time between the first time and second time is greater than a predetermined period of time; and determining if the camera has changed from either a day mode of operation to a night mode of operation or a night mode of operation to a day mode of operation; performing an auto-focus operation if the change in temperature between the first temperature and the second temperature is greater than the predetermined temperature change the level of light sensed in the field of view of the camera at the second time is within the predetermined light level range, and the period of time between the first and second time is greater than a predetermined period of time; and performing an auto-focus operation if the camera has changed from either a day mode of operation to a night mode of operation or a night mode of operation to a day mode of operation.