I first became interested in photography and cameras in the 1970s when 50mm f/1.4 lenses were the standard normal lenses for single-lens reflex cameras. Naturally, manufacturers offered slightly slower 50mm f/2 and 55mm f/1.8 lenses, but they were positioned as lower-priced versions of f/1.4 lenses. Where the user's budget allowed, f/1.4 lenses were preferred and even recommended by camera shops.
Many may have forgotten that this was the time of Leica's popular rangefinder cameras, when normal lenses generally had a maximum aperture of f/3.5 or f/2.8, or f/2 a little later on. While faster f/1.5 lenses were also available, they were considered specialty lenses for shooting in dark situations. So, why did f/1.4 lenses become the standard for normal lenses in the age of SLR cameras?
Perhaps one of the reasons lies in the structure of SLR cameras, with which the view through the lens is projected in the viewfinder. Compared to today's SLR viewfinders, viewfinders on early SLR cameras were extremely dark making fast lenses necessary to preserve viewfinder brightness. In addition, we cannot overlook the fact that with the switch to SLR, camera bodies became larger allowing larger lenses to be used in terms of overall balance. However, these reasons alone are not sufficient. The primary reason is that, in addition to their superior performance at maximum aperture, f/1.4 lenses had been developed to offer performance equal to that of slower lenses when the aperture was stopped down.
Many readers surely recognize the fact that faster lenses mean better performance. This awareness generally holds with today's lenses. Faster lenses, or those with larger maximum apertures, allow users to take advantage of bokeh, yet offer performance equal to that of slower lenses when the aperture is stopped down. Personally, I recommend the fastest lenses a user's budget will allow.
However, in terms of lens design, it was not certain that a faster lens would offer the level of performance needed to make it an all-purpose lens. This is because faster lenses require more lens elements. In addition to increasing ghost and flare, more lens elements also make it difficult to maintain balanced performance at maximum aperture and when the aperture is stopped down. Therefore, with "classic" fast lenses, performance when the aperture was stopped down (maximum aperture is probably not used with many scenes) was often inferior to that of slower lenses. Of course there were also battles for lens size and price, but this performance issue was that reason that fast lenses were positioned as specialty lenses.
The Nikkor-S Auto 50mm f/1.4 introduced in tonight's tale did away with the shortcomings of previous fast lenses, making f/1.4 lenses the standard for normal lenses.