OK fair enough.
I was surprised to find my 105mm f3.8 Ross Xpres covers 5x4 as does my 105mm f4.5 Tominon, how sharp they are at the edges I've yet to find out.
You mean "covers 5x4 centimeters", right?

Because if you mean the Ross Xpres for the 6x9 folders, well, i own one and it may appear to cover a big area but it struggles to keep things tack-sharp out of a 6x6 area !!! And i've tried re-adjusting the focus with a ground glass. Inside the 6x6 area everything is very sharp, though.

. I also have a spare Ross 107mm f3.8 Ensar which apart from being unclothed is identical, seems to be a prototype of the 105mm Xpress SN 1007. I don't expect sharp edges and corners but will try it out of curiosity.