With an AF-S motor, the NIKKOR 50mm f/1.8G will be capable to auto-focus on any camera even the entry level ones which don't offer an AF motor, like the Nikon D3100. It should also make the focusing movements of the lens quieter and faster on all cameras.Image Quality MeasurementsLet's first have a look at the DxOMark results to see how this lens compares with its acclaimed predecessor and if there is more than the AF-S motor to justify a price twice as high as the AF Nikkor 50mm f/1.8D, especially if your camera has an AF motor.AF-S NIKKOR