Leica APO-Summicron-SL 90mm F2 ASPH is an Auto Focus (AF) Telephoto Prime lens with 35mm FF max sensor coverage. When mounted on a 35mm FF sensor camera, it will give you an FF equivalent focal range of 90mm. Providing a max aperture of f2 at 90mm, this lens is very fast.
Leica APO-Summicron-SL 90mm F2 ASPH is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.