This 24mm lens was the standard prime for the Pentax Auto 110, the smallest interchangeable-lens SLR system ever produced. Because the 110 film frame is roughly a quarter the size of 35mm, this 24mm focal length provides an equivalent field of view to a "normal" 50mm lens on a full-frame camera. A unique technical feature of this system is the lack of an aperture diaphragm within the lens itself; the aperture and shutter blades are located inside the camera body. This makes the lens incredibly small and lightweight, consisting only of the optical glass and a focusing ring. The lens is well-regarded for its sharpness despite the limitations of the 110 format.