Patent ID: 7133220

Claim:
A reading lens comprising: five lenses including at least two positive lenses and two negative lenses, wherein the five lenses include a positive first lens, a positive second lens, a negative third lens, a negative fourth lens and a positive fifth lens sequentially arranged from the object side of the reading lens, the positive second lens and the negative third lens are cemented as a single cemented lens having a negative refracting power, an aperture stop is disposed between the negative third lens and the negative fourth lens, the negative fourth lens includes an aspherical lens, a curvature radius of a first surface of the aspherical lens on an object side of the aspherical lens is r 1 a , a curvature radius of a second surface of the aspherical lens on an image side of the aspherical lens is r 2 a , and r 1 a and r 2 a satisfy: 1.4< r 2 a/r 1 a< 2.3.