Maybe mention for people new to photography that any lens with an f number of 2.8 or lower, is referred to as a "fast"
lens. (referring to the faster shutter speed you can use when you have more light available)
Also, check this out: http://www.visual-memory.co.uk/sk/ac/len/page1.htm
it's an f/0.7
(!!!) lens Stanley Kubrick used to film by candlelight