Nikon Nikkor 50mm f/1.2

Another lens I use with my Nikon Fa is Nikkor 50mm f/1.2

The advantages of the f/1.2 maximum aperture of this lens are twofold. The first, of course, is that the lens can be used in low-light level shooting either indoors or outside under very dull conditions. particularly when working with slow color film. The second is ease of focusing. An f/1.2 50mm lens has, at maximum aperture, very little depth of field and this can be used to advantage to secure pinpoint focusing under virtually all shaming conditions. The shallow depth of field can also be used by the creative photographer for interesting selective focusing effects. The Nikkor 50mm f/1.2 lens couples fully to both the full-aperture metering systems and automatic diaphragm mechanisms of all Nikon and Nikkormat cameras. In the case of non-AI type cameras, manual indexing of the lens' maximum aperture is required. The Micro Nikkor 55mm f/2.8 is recommended for close-up photography when high resolving power is required.

This information is taken from the user manual of the lens.