This special lens design combines one aspherical lens surface, one lens element with anomalous partial dispersion and two other lens elements made of optical glasses with high indices of refraction to give this compact unit outstanding contrast - and detail rendition - even at full aperture. An accessory brilliant viewfinder is needed for checking the field of view, whereas focusing and exposure metering are performed through the camera's own viewfinder. This high-performance lens also makes it possible to work efficiently in cramped quarters. It adds a more dynamic feeling to close-up pictures and it gives landscape photographs significantly more depth.