Canon DSLR bodies prevent poor auto-focus performance by disabling it completely when the lens reports maximum aperture at chosen focal length smaller than f/5.6. This implies that some lenses will ...
I've found that some discontinued teleconverters, such as the Pentax F 1.7x AF Adapter and Nikon TC16A, enable autofocus with manual focus lenses. How is this possible? Does this system have any ...