An optical system, including, sequentially from an object side to an image side: a first lens; a second lens; a third lens; an aperture; a fourth lens; a fifth lens; a sixth lens; a seventh lens; an optical filter; and a photosensitive chip. The first lens is a meniscus aspherical lens. The second lens is a meniscus aspherical lens. The third lens is a biconvex aspherical lens. The fourth lens is a meniscus aspherical lens. The fifth lens is a meniscus spherical lens. The sixth lens is a meniscus spherical lens. The seventh lens is a biconvex aspherical lens.