a six - piece optical lens system comprises , in order from the object side to the image side : a stop , a first lens element with a positive refractive power having a convex object - side surface and at least one aspheric surface ; a second lens element with a negative refractive power having a concave image - side surface and at least one aspheric surface ; a third lens element with a positive refractive power having a convex image - side surface and at least one aspheric surface ; a fourth lens element with a positive refractive power having a concave object - side surface and at least one aspheric surface ; a fifth lens element having a convex image - side surface and at least one aspheric surface ; a sixth lens element with a negative refractive power having a concave image - side surface and at least one aspheric surface . thereby , the total track length of the system will not be too long .