I obtained a used 100mm Xenar and mounted it on my Century Graphic to replace an unremarkable triplet (Graftar). Center is tack sharp, Left is tack sharp, but Right is a tad bit less sharp when critically examining negatives with a loupe. For example, a city scene (with skyscape in the background, with lots of minute details) taken at f8 on a tripod, focused with the ground glass. This is using sheet film (not the roll back). With a precision level, and the camera mounted on a copy stand, I have checked alignment of the front and it is dead square with the back (also the infinity stops reflect the same). Same holds true for looking at the focused image on the ground glass with a loupe (difficult since the edges are darker). The lens was from another camera that covered the 6x9 format (Technika) and is fairly modern (circa 1971) in a Compur. A visual inspection of the lens indicates not as much as a mark or flaw of any type in the glass itself or the coating. What else should I check? My next test is to take the same shot and rotate the lensboard to see if the problem moves to the opposite edge.

Are the lens cell housings free of any dents or dings? Also what about the mountings to the shutter? A verry minute bend could cause this.

Charles