I find its amazing that there are so many posts here that appear to be defending the 5DMk3 ability to focusing ability in low light. Guys, the 5D3 are many things and it has a great focusing system - but its ability to focus in the dark is atrocious, compounded by the lack of a pop up flash i would say it is one of the most significant short comings of the 5D3. Canon recognizing this have improved low light focusing in the 6D and I am sure that every pro dslr released henceforth will be superior to the 5D3 in low light focusing. If this could be improved via firmware I wish canon would fix this. There is no easy solution for this other than to walk around with a flash light. I heard that there was a laser assist someone was working on but i have not seen it.Most of my photography with the 5D3 is in low light and I find the focusing to be excellent, at least as good as any other camera I've used in the past 10 years. And most Canon flashes have a built-in autofocus assist light, so I don't know why anyone would need a laser assist.
I am wondering, is 5D3 with flash assist light beat the EV-3 low light focusing of 6D?
I currently use 5D2 with 430exII... Still undecided to go to 5D3 AF or 6D low light... Anyone has any scientific idea on how low 5D2 with 430exII can focus?