"During my short time with the Horseman SWD2, you needed to set the 35mm Rodenstock lens at about the 4/5m lens mark to achieve focus at infinity!! Something seriously not right and it is boxed up to go back now the CamboWDS has arrived.
Something that concerned me more with the Rodenstock when tested was that optimum infinity focus (at wide open) was not achieved at the same lens mark!! When I had the loan Cambo before with the Schneider 35mm lens I did not undertake a rigorous test but I shall be doing that with the new kit that I have purchased."
I have an Alpa 12SWA. The adapter for the H1 mount came with shims (super-thin gaskets really). I had to remove 1/10th of a millimeter from the shimming to acheive critical focus. Before that, the 35mm lens would focus about 50' out when set at infinity. I did have one lens, out of 4, not focus properly. It was exchanged by the dealer.
Aside from testing each lens carefully when I buy it, it is also necessary to test each MFDB before assuming the markings on the lens will give me good focus. I had one P45 that was 1/10th millimeter different than the other P45 and four Aptus 75's I've used. With my current shimming, that P45 would severly back-focus if I went by the numbers on the lenses.
I wish I could unmount some of my digitars to use on lensboards for other view cameras, but the tollerences for the focus mount are just too small. I remember when you would rent a lens and they would just throw it on any lensboard you needed for your 4x5 camera.
"one thing struck me was whether the centre filter used on the Rodenstock lens could have been of any influence on the plane of focus at infinity?"
Only filters BEHIND the lens change the focus plane. Center filters should pose no problem.