Optical imaging system

An optical imaging system comprising:

• a first lens having positive refractive power, a convex object-side surface in a paraxial region thereof and a convex image-side surface in a paraxial region thereof;
• a second lens having negative refractive power and a convex object-side surface in a paraxial region thereof;
• a third lens having refractive power;
• a fourth lens having refractive power, and
• a fifth lens having refractive power,
• wherein the first to fifth lenses are sequentially disposed in ascending numerical order along an optical axis of the optical imaging system from an object side of the optical imaging system toward an imaging plane of the optical imaging system,
• wherein the optical imaging system has a total of five lenses,
• wherein |f/f1+f/f2|<1.2 is satisfied, where f1 is a focal length of the first lens, f2 is a focal length of the second lens, and f is an overall focal length of the optical imaging system, and
• wherein 0.8≤TTL/f≤0.95 is satisfied, where TTL is a distance along the optical axis from the object-side surface of the first lens to the imaging plane.