If you shell out for FoCal, be sure to get the Pro version. It will make the adjustments automaticily to your camera. Plus it will give you the sweet spot on each lens you test. My 50D would hold information on up to 20 lenses, and add the data as it identified each lens as you mount it. For each lens, it may take an hour to aim the camera, make zoom adjustments, and finally for the program to calculate the results. But, it will be right on, and you will notice a difference in you IQ.
