The new Canon 5D Mark III allow you to activate a 6x4 grid in the viewfinder. Does anyone know the use of such a grid (instead of a more classic 3x3) for composition, besides obvious horizontal/vertical alignment?
Another thing to note: the Mark III allow you to use either 3x3 (with or without diagonals) or 6x4 grid when reviewing pictures, or when shooting through the LV screen, but only the 6x4 grid when using the VF...??? Maybe in a future firmware?
This was the real starting point for my question. Anyway, thanks to all fellows who took time to post answers!