Fish eye monitoring optical system and lens applying same

One embodiment of the invention discloses a fish eye monitoring optical system. The system at least successively comprises a front lens group and a rear lens group from an object surface to an image surface along an optical axis, wherein the front lens group comprises a first lens, a second lens, a third lens and a fourth lens; and the rear lens group comprises a fifth lens, a sixth lens, a seventh lens and an eighth lens. On the other hand, another embodiment of the invention also provides a lens. According to the embodiments of the invention, the front lens group and the rear lens group are provided with eight lenses all together, the number of the lenses is reduced, and the structure is simple; and besides, optical conditions which are met by the optical system or the lens enable the optical system or the lens to have excellent performance of large aperture, high resolution, day and night confocal property the like.