1. A method for focusing an electronic imaging system, the method comprising the steps of: S1: pre-focusing an object; S2: receiving a first pixel image; S3: generating at least two first histograms of at least one region of the first pixel image using at least two different frequency components; S4: finding widths of the at least two first histograms and storing them as a first focus measure; S5: moving a focus lens; S6: receiving a second pixel image; S7: generating at least two second histograms of at least one region of the second pixel image using the at least two different frequency components; S8: finding widths of the at least two second histograms and storing them as a second focus measure; S9: finding a difference between the second pixel image's high frequency component histogram width and the first pixel image's high frequency component histogram width; S10: determining whether there is a difference, wherein the difference is other than zero; and S11: determining a focus direction signal using the higher frequency component histogram widths as the focus measures if there is a difference other than zero, otherwise using the lower frequency component histogram widths as the focus measures.