The D5100 improves upon the D5000's ISO performance, taking after the D7000's lead in this area. It produces quite clean images up to ISO 1600, and even though ISO 3200-5000 produces more usable noise, the images still look workable. The images return approximately 2000 x 1800 LPH (horizontal x vertical) on our resolution chart, almost (but not quite) as detailed as the D7000's 1800 x 2200 LPH. Above ISO 6400 into the Hi settings, image noise becomes overwhelming. Auto-focus is fast and accurate, and makes shooting with the camera fun and easy.