OPTICAL IMAGING SYSTEM

An optical imaging system includes a first lens group, a second lens group, a third lens group, and a fourth lens group 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 image side of the optical imaging system, at least one lens group among the first lens group to the fourth lens group being configured to be movable along the optical axis; and a reflective member disposed on an object side of the first lens group and comprising a reflective surface configured to change an optical path, wherein the first lens group has a positive refractive power, and 0.8≤Fnot/Fnow≤1.3 is satisfied, where Fnot is an F-number of the optical imaging system in a telephoto mode, and Fnow is an F-number of the optical imaging system in a wide-angle mode.