The invention discloses a low-cost
optical imaging system with a
large aperture, which is sequentially provided with a first lens, a second lens, a diaphragm, a third lens, an aspheric double-glued lens and an
optical filter from the object side to the image surface; the aspheric surface The doublet lens comprises a fourth lens and a fifth lens cemented together, the first lens and the fourth lens are all negative
focal length lenses, the second lens, the third lens, and the fifth lens are all positive
focal length lenses, the first lens, the second lens The second lens, the fourth lens and the fifth lens are all aspherical lenses, the third lens is a spherical lens; the
focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, and the fourth lens The focal length of the fifth lens is f4, and the focal length of the fifth lens is f5, where f1, f2, f3, f4, and f5 satisfy: f1<‑3, f4<‑60, f5>30,0.05 <f1 f4<5,‑5<f1 f5<5,f2 f3>2. The aperture of the
optical imaging system of the present invention reaches more than Fno1.6, and the relative
illuminance reaches more than 70%, which can effectively control the aperture and thickness of the lens and reduce the tolerance sensitivity of the
system.< / f1>