Back in the day, the camera I used had a handy split prism focusing screen. It made a breeze of manual focus. Of course, my current Canon 5D has nothing like that. So when I'm shooting at big apertures, like sub f/2.8, I have to rely on spot auto-focus, which usually works. But sometimes, misses it. Especially if I'm close up and the difference between an eye and an eyelash is a big deal. I know that aftermarket screens are made for the 5D, I'm just wondering if anyone has any actual personal experience with them. So, what do you think?