Lensrentals' Roger Cicala has published the third part of his investigation into Canon's autofocus systems, looking at what's changed behind the marketing claims. It's not unusual for manufacturers to promise that their products are 'new and improved,' but explanations about what's been changed or how much of an improvement it offers are harder to come by. Cicala has delved into Canon's patents (and taken some lenses apart), to see exactly why the EOS 5D Mark III's focus so consistently out-performs its predecessors'.