Autofocus is one of the most important aspects of any camera. There has been much debate over the past few years about how well autofocus performs on the various camera models. We originally developed this AF torture test as part of an ongoing article about the autofocus problems that surrounded the original introduction of the Canon 1D MKIII. Using this test we were able to discern that there was most likely a hardware issue at the root of these AF problems. And, so there was. Anyway, people seemed highly interested in this particular autofocus test, so we continued to conduct this test during various camera reviews.
How we test:
The tests are fairly simple and straightforward. A camera is placed on a tripod and a runner runs directly at the camera at a steady pace. The tests are all performed using servo focus mode at f/2.8 using the best 300mm f/2.8 lenses available from the respective camera manufacturers. The camera exposure is set to ensure that a very high shutter speed (usually 1/2000 or higher) is achieved throughout the run. Normally, at least 5 test runs are conducted and then coded for the number of in focus images in each sequence. A percentage is then taken for each test run. These 5 percentages are then averaged to get an overall result. These tests are all done using the default camera settings and default custom function settings. Tests are done using the center focus point only, all available focus points, or both.
This is a specific Auto Focus torture test, not an overall Auto-Focus score:
Please note that these results do not necessarily reflect the overall autofocus system performance of any particular camera. They do provide a lot of insight into how well the AF systems stand up to one of the toughest tasks they can possibly face.
So far, we have tested the Nikon D300, Canon 1D MKIII, Canon 40D, Nikon D3, Canon 1DS MKII and Canon 7D.