As part of our image quality testing for the Nikon D5100, we've shot our resolution chart with a Sigma 50mm f/1.4 EX DG HSM lens mounted.

If you view our crops of the resolution chart's central section at 100% (or Actual Pixels) you will see that, for example, at ISO 100 the Nikon D5100 is capable of resolving up to around 26 (line widths per picture height x100) in its raw files and 24 (LWPPH x100)in its highest quality JPEG files.

Examining images of the chart taken at each sensitivity setting reveals the following resolution scores in line widths per picture height x100:

Full resolution chart image

JPEG images

ISO 100 resolution chart image crop

ISO 100 JPEG score: 24, full image

ISO 200 resolution chart image crop

ISO 200 JPEG score: 24, full image

ISO 400 resolution chart image crop

ISO 400 JPEG score: 24, full image

ISO 800 resolution chart image crop

ISO 800 JPEG score: 24, full image

ISO 1600 resolution chart image crop

ISO 1600 JPEG score: 24, full image

ISO 3200 resolution chart image crop

ISO 3200 JPEG score: 22, full image

ISO 6400 resolution chart image crop

ISO 6400 JPEG score: 20, full image

ISO h0.3 resolution chart image crop

Hi 0.3EV over ISO 6400 score: 20, full image

ISO h0.7 resolution chart image crop

Hi 0.7EV over ISO 6400 score: 20, full image

ISO h1 resolution chart image crop

Hi 1EV over ISO 6400 score: 20, full image

ISO h2 resolution chart image crop

Hi 2EV over ISO 6400 score: 18, full image

Raw images

ISO 100 resolution chart raw image crop

ISO 100 raw score: 26, full image

ISO 200 resolution chart raw image crop

ISO 200 raw score: 26, full image

ISO 400 resolution chart raw image crop

ISO 400 raw score: 26, full image

ISO 800 resolution chart raw image crop

ISO 800 raw score: 24, full image

ISO 1600 resolution chart raw image crop

ISO 1600 raw score: 24, full image

ISO 3200 resolution chart raw image crop

ISO 3200 raw score: 22, full image

ISO 6400 resolution chart raw image crop

ISO 6400 raw score: 22, full image

ISO h0.3 resolution chart raw image crop

Hi 0.3EV over ISO 6400 raw score: 20, full image

ISO h0.7 resolution chart raw image crop

Hi 0.7EV over ISO 6400 raw score: 20, full image

ISO h1 resolution chart raw image crop

Hi 1EV over ISO 6400 raw score: 20, full image

ISO h2 resolution chart raw image crop

Hi 2EV over ISO 6400 raw score: 18/20, full image