The Frilon 50mm f1.5, modified for Leica M cameras. Introduced as a high-end model for the Futura S, manufactured by Futura Kamerawerk in Freiburg, southern Germany, between 1952 and 1957. Although the glasses features 6 elements in 4 groups, it is not a double Gauss type. Despite its compact and lightweight design, it boasts a bright f1.5 aperture. This lens has gained a cult following as a hidden gem. At full aperture, it delivers a notably soft rendering, with its sweet spot reached around one stop down. It exhibits characteristic vintage lens qualities, including pleasing bokeh and some peripheral distortion, resulting in elegant and delicate imagery with beautiful diffusion. Futura remains a mysterious manufacturer, yet within a short period, it produced remarkable large-aperture lenses such as the Frilon 50mm f1.5 and the Frilon 70mm f1.5, designed by engineers from Schneider. (With reference to an article by oldlens.com). Rare item. It shows minimal signs of use, with no noticeable scratches or significant blemishes, presenting a clean exterior. In 2023, fully serviced along with modification to M-mount. The operational feel of each part is exceptionally smooth. Through meticulous rangefinder coupling cam processing, it reliably synchronizes with the rangefinder from around 0.7m to infinity. While there are some shallow wiping marks on the front and rear elements, there is no haze present. Considering the tendency for Frilon lenses to exhibit significant wear on the glass, this lens is in good condition. Peaking is accurately displayed in live view on degital camera, and test shooting results were highly satisfactory. The filter thread size is 39mm. Additionally, a Leica UVa II filter is included with this item.