This is a printable chart for calibrating the autofocus of a digital camera. Super useful, made a bid difference for my D7100 (which has always had some AF issues).

Jeffrey Friedl’s Blog » Jeffrey’s Autofocus Test Chart

Nikon D200 + 70-200mm f/2.8 @ 70mm
— 1/320 sec, f/2.8, ISO 400 — full
exifTesting SLR Autofocus