A method of focusing dual cameras including receiving a fixed focus image from a fixed focus camera module, receiving an auto focus image from an auto focus camera module, calibrating a lens distortion of the auto focus camera module, calibrating a geometric relation of the auto focus camera module and the fixed focus camera module, calculating a depth of focus difference between the fixed focus image and the auto focus image, estimating an auto focus position based on the depth of focus difference and setting the auto focus position based on the estimation.