Patent ID: 8064761

Claim:
A method for fast auto focus of a digital camera, comprising: a) adjusting an auto focus lens of a digital camera to at least three focus positions, wherein said focus positions equidistant apart; b) measuring a value of sharpness and focus motor position at each of the “at least three” focus positions, wherein at least one focus position is before a best focus position of the focus motor and at least one focus position is after the best focus position of the focus motor; c) determining a focus trend from said sharpness values at said focus positions; d) determining an estimated best focus position of said lens by an interpolation; wherein the estimated best focus position determined by adding together one half a value of the focus motor position before the best focus position to one half the value of the focus motor after the best focus position and one half the value of a calculated offset, wherein the calculated offset determined by whether a first angle established by ascending focus measurement data points or a second angle established by descending focus measurement data points is larger, wherein the calculated offset is a positive value when the angle between descending focus measurement data points is larger, and wherein the calculated offset is a negative value when the angle between ascending focus measurement data points is larger; e) verifying said estimated best focus position as actual best focus position; and f) adjusting said auto focus lens to said actual best focus position.