
My favorite lens, and one that every photographer should have in their arsenal, is a "fast 50." When I bought my digital SLR camera I said no to the temptation of an inexpensive "kit" lens and instead put the money into a 50 mm f/1.4, which cost about $400. Even if you can't afford the f/1.4, you can get a 50 mm f/1.8, which will work just fine, for $140.
Two reasons why you need a "fast 50." First, we all find ourselves in low light situations where a zoom lens, like my 18-200 mm VR f/3.5-5.6, just won't cut it. This past summer when we were in Ireland, we attended the Willie Clancy Traditional Music Festival.

During the day students attend clinics and in the evening all of the pubs fill with musicians and spectators for "sessions." In the dimly lit pubs, by cranking my ISO up to 800 and my aperture on my 50 mm lens opened up to f/ 1.4 to 2.0, I was able to capture some decent images. These photos wouldn't ever be accepted on iStock, but I'm very glad I have these images captured.
The second reason that the "fast 50" is a must have lens, is because it gives the photographer the ability to use a very shallow depth of field and throw the background into a soft creamy blur. This technique really makes the subject seperate and stand out from the background. If you don't have a "fast 50", this is the next piece of gear to add to your kit.