I sometimes struggle to get manual focus, even with LiveView, on my 70D primarily because of my not-so-good-anymore eyesight. I read an article on macro photography where the author mentioned how useful a focusing screen (FS) was for macro and /or fast. I presume these focusing screens replace the default camera one? makes a FS for the 50D and 60D which apparently is also compatible with the 70D. Does anybody know if these screens impact on autofocus? Also, comments on a FS vs LiveView focusing or related would be greatly appreciated.