It seems we are being led a merry dance by the lens makers so we will buy new lenses:
our existing LF film lenses gave us nice image circles with movements for 6x9cm or 4x5" film cameras A
then MF digital came along and:
we had to buy new lenses with 'digital' resolution and minimal coverage for 645 sensors only B
then stitching MF digital cameras came along and:
we now have to buy digital lenses with bigger image circles to cover stitching C
some C lenses seem to be reheated A lenses, with very minor changes.
many B lenses offer almost no stitching range.
and companies like Alpa, wont allow you to get your own LF film A lenses mounted, forcing you to buy new C lenses, even though they are perfectly good, and very similar, except for the word 'digital' on the barrel !