The present disclosure is related to a lens systems. The lens system includes, in order from an object side to an image side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, and the lens system satisfies the a ≤ f 1 f ′ ≤ b , c ≤ f 2 f ′ ≤ d , e ≤ f 3 f ′ ≤ f , following condition: and at least partial of G3 is made of material satisfying the following condition: Vd>g and dn/dt≤h, wherein a, b, c, d, e, f, g and h are constants, f1 represents a focal length of G1, f2 represents a focal length of G2, f3 represents a focal length of G3, f′ represents a focal length of the lens system, Vd represents an abbe constant, n represents a refractive index, t represents temperature, and dn/dt represents a differential of refractive indices against temperature.