Cameras with an APS-C sized sensor are generally not thought of as low-light performers. Despite recent gains in 16 megapixel APS-C technology (NEX-5n, Fuji X-Pro 1), digital noise due to tiny pixels not getting enough light can become a problem at high ISOs starting at about ISO 3200. When packing a 24 megapixel sensor of the same size, these even smaller pixels are all the more susceptible to image degradation. On my NEX-7, I have generally stayed away from low-light (handheld, anyway), simply out of the fear of a low signal-to-noise ratio at high ISOs. But when the job calls for it–an acoustic/electronic music show hosted in a bar–pictures have to be made, so I grabbed my Nikon 50mm f/1.4 S-Auto, and went to work. 
To give an idea of the (lack of) stage lighting, this guy’s computer was illuminating him more than anything else in the room!
Soprano Sax and the Macbook
50mm, ISO 1600, f/1.4, 1/60
