This item is an accessory. It must be rented with a non-accessory item.
With many of today's lenses featuring autofocus, most people's requirements on how sharp a lens is will not matter if it can't focus accurately. We've all heard the stories of people buying multiple copies of the same lens and testing them all to find the most satisfying copy. If you're working with a lens that you feel isn't 'as sharp as it used to be' the Datacolor Spyder LensCal is here to help. It provides an AF target (which needs to be set up level to the sensor plane) and once focused, the slanted ruler shows whether the lens is focusing accurately or front focusing/back focusing. Both Canon and Nikon have ways to calibrate the focus system in newer models (Canon calls their system "Micro Focus Adjustment" and Nikon "AF Fine Tune") to avoid sending your lenses off to be calibrated. Using these two systems and the Datacolor Spyder LensCal, making accurate focusing micro adjustments is possible in the comfort of your home without shipping your lens off.