Abstract: An optical imaging system includes a first lens having an image-side surface that is concave; a second lens having a refractive power; a third lens having an object-side surface that is convex; a fourth lens having an image-side surface that is concave; a fifth lens having a refractive power; and a sixth lens having a refractive power and an image-side surface having an inflection point, wherein the first lens through the sixth lens are sequentially disposed in numerical order from an object side of the optical imaging system toward an imaging plane of the optical imaging system, and the optical imaging system satisfies TL/(2Y)?1.01 and 1.2?tan ?, where TL is a distance from an object-side surface of the first lens to the imaging plane, 2Y is a diagonal length of the imaging plane, and ? is half a field of view of the optical imaging system.

Abstract: The present invention relates to an accessory mounting apparatus. The present invention provides an accessory mounting apparatus for being fastened to an accessory mounting rail mounted on a firearm so as to mount accessories including a mounting cover which has a first fastening groove fastened to one side of the accessory mounting rail and a mounting base which is connected to the mounting cover and has a second fastening groove fastened to another side of the accessory mounting rail, wherein the mounting base has an accessory mounting means for fixing a variety of accessories.