If you are accustomed to shooting in low light with a variable aperture f/3.5-5.6 kit zoom lenses, get ready for a pleasant surprise: Today’s 50mm f/1.4 lenses make sharp photography possible in the kind of light so dim, you probably would have left your DSLR camera in its bag before.
Several factors contribute to give the 50mm lens its superb low light performance. First and most obviously, the high-speed f/1.4 maximum aperture allows more light through to the image sensor than almost any other lens available today.
Second, the compact dimensions of the 50mm lens are – compared with more long-barrelled lenses – less apt to magnify camera shake.
Third, if your DSLR camera body is blessed with sensor-based shake control, it will give you yet another stop or two of sharpness when lights are low.
Finally, with each generation, the sensors in today’s DSLR cameras are getting much better at suppressing image softening noise in dimly lit shadows, even when you’ve dialed in high ISOs.
Add these factors together, and you see how a 50mm f/1.4 lens lets you leave tripod and flash at home.