Nikon 50mm f/1.4 D AFI'd get one here if I was buying a new one.
This is a very fast professional lens that has features which make it desirable as a portrait lens.
Due to its speed, it makes a great lens for indoor photography when a flash can't be used.
Although this lens isn't "cheap" at over $300US, it is in a league of super high-expensive premium professional lenses like the $1,000+ 85mm f/1.4 or the hard-to-find 28mm f/1.4 which fetches $3,000 or more on today's market.
I admit that I first owned the 50mm f/1.8D and never planned to own one of these f/1.4 lenses. The f/1.8D costs about a third for a brand new lens with full warranty. The reason I got one of these f/1.4 was my local brick-and-mortar camera store's used sales area had a very good price.
I think what happened was that someone traded in an f/1.4 and the sales person looked it up in some book and misread it as an f/1.8 and put a $100 price tag on this one. So, I found an f/1.4 for $100 in practically brand new shape with original box and everything.
If you can find a great deal, like I did, on an f/1.4 lens, get one. Otherwise, just invest in the great 50mm f/1.8D and be happy taking great photos.
This little lens is heavy for its size topping the scales at 9 ounces.
It has 7 elements in 6 groups with the aperture using 7 blades.
Maximum Aperture: f/1.4
Minimum Aperture: f/16
This lens is amazingly super sharp and will wow you the first time you use one.
There is some slight vignetting and a little loss of contrast if you shoot wide open (f/1.4) but if you stop down to around f/4 this is completely gone.
Why take such a fast lens and stop it down? Well, there are two good reasons. One, is that you don't need insanely tight DOF (depth of field), and the other is that this lens at f/4 is perfection in optics. Other lenses, which are slower to start, have to stop down to f/8 before their numerous optical issues clear up.
So, a faster lens, when stopped down to its perfect balance (in this case, f/4) still yields a faster "sweet spot" than a slower lens. It is as simple as that. For more information on this concept, read my article Why a good lens matters.
Following are some sample photos to demonstrate the power of this type of lens and some general uses which will likely yield good results. If you shoot things like these, then this lens may be a good one to think about adding to your camera bag.