Noctilux

The name Noctilux is used by Leica to designate camera lenses that have a maximum aperture of f/0.95. This is the largest f-number offered by Leica in its lens range. The lens has been in production since 1966 and carries on to the present day. So far all Noctilux lenses have been made for the Leica M mount.
History.
The name Noctilux is a combination of "Nocti", which is derived from the word nocturnal, while "Lux" is Latin for light.
Description.
The Noctilux lenses have the largest maximum apertures in the Leica range. With various models having f-numbers of f/0.95 or f/1.0 or f/1.2 or f/1.25 as its maximum aperture. It is also the heaviest of all of Leica's lenses.
Market position.
The Noctilux is the most expensive lens in the Leica lens range. It is followed by the Summilux.