I've been trying to make do with my Rodenstock 55mm APO Sironar-Digital on my Credo 60 / Linhof Techno platform, making 6x13 panoroamic stitches. It's a good lens on centre but when shifting out to the extremes I regularly do, e.g. 17mm horizontal shift each way, plus often about 6mm rise / fall of the back, the edges turn to mush. From what I gather from inspecting the files, the problem is twofold.
1: Sharpness falloff and
2: Light falloff, which exacerbates noise and detail smearing when applying an LCC.
I know the best option for the sceario is the SK 60mm XL, but I wonder if anyone has some files they might be able to share so I can assess how much better it might be? I'm assuming it's lightyears ahead, but I've learnt to downplay my expectations on gear items that might be considered something of a magic bullet...
For those that use the 60 XL, at the movements I've mentioned how essential is the use of a centre filter for light falloff?
For those familiar with the RS 55 APOSD, would a centre filter do anything to help me save money, of would it simply be a waste of money?