A type of camera lens, or to go really fast
[DOC] [TLE] Lens speed - Wikipedia [PAR] Lens speed refers to the maximum aperture diameter, or minimum f-number, of a 
photographic ... With 35mm cameras, the fastest lenses are typically in the "
normal lens" ... 50mm f/1.8D are very inexpensive, but quite fast and optically well
-regarded.