Y'know, the 35/4.5 Apo Grandagon just covers 6x12. Just. And the center filter really is needed. Not to denigrate the Xpan, but its sort of like the Alpa 12. Lovely, a joy to behold, according to users a pleasure to use but there are less expensive ways of doing what it does, and more. The 35 Apo Grandy isn't cheap -- I ended up paying a grand for mine and its center filter, bought 'em separately -- but there are quite inexpensive 6x12 roll holders and 4x5 cameras that will focus it.