A four-piece optical lens for capturing image is provided. In order from an object side to an image side, the optical lens along the optical axis includes a first lens with positive refractive power, a second lens with refractive power, a third lens with refractive power and a fourth lens with refractive power. At least one of the image-side surface and object-side surface of each of the four lens elements are aspheric. The optical lens can increase aperture value and improve the imagining quality for use in compact cameras.