The Datacolor SpyderLensCal Autofocus Calibration Aid is a focus test chart, designed for use with select DSLRs that support autofocus adjustment. The chart allows you to test the autofocus accuracy of your camera - making it easy to fine-tune it for optimum performance.The SpyderLensCal features a built-in level and tripod mount, allowing you to create precise testing environments. Cameras that support autofocus adjustments include the Canon 50D, 7D, 5D Mk II, 1D Mk III, 1D Mk IV, and 1Ds Mk III, the Nikon D300, D300s, D700, D3, D3s, and D3x, Sony A850 and A900, the Olympus E-30 and E-620, and the Pentax K20D, K-7, and K-5.