Low distortion with high resolving power With a focal length equivalent to 18mm in the 35mm format, this super wide-angle lens is optimal for shooting landscapes and architectural photography. With a 12 groups and 15 elements construction using two aspherical lenses, one super ED lens, and three ED lenses, this lens suppress distortion despite being a super wide-angle lens with a 99.9° angle of view. Also, thanks to the optimal arrangement of the Super ED lens and three ED lenses, chromatic aberration of magnification is thoroughly suppressed, achieving high resolution performance all the way to the edges. Nano GI coating​ Nano GI coating has been applied to the lens that is effective on incident light entering the lens from diagonal angles due to the nature of the super wide-angle lens. Despite being a super wide-angle lens, the occurrence of ghosting and flare is effectively suppressed. Fast and quiet AF​ By adopting an inner focusing AF system to lighten the weight of the focus lens, and using a linear motor to drive the lens elements, fast and quiet AF is achieved, allowing for comfortable shooting. Dust and weather resistant, capable of operating in environments as cold as -10°C​ The lens has been sealed in nine areas, allowing you to shoot with confidence and stability, even in dusty environments and in light rain outdoors. High operability The aperture ring has a C position (command dial mode) to allow lens aperture value to be changed via the command dial on the camera body. A locking mechanism has been added to the A (Auto) and C positions to prevent unintended movements of the aperture dial.