Re: Weird Coverage with Wollensak 159mm Velostigmat ?
I haven't used mine (the 9.5 version) enough to verify this, but supposedly the difference between the two lenses is that the 9.5 was designed for banquet cameras, has minimal movements, but achieves maximum sharpness at nearly wide open. This makes sense for a lens designed to be used for group shots inside with relatively darker light, achieving front-back focus by simply tilting the back, with no need to engage in perspective correction. The 12.5 version is more normal, for regular view camera use, has wider coverage, allows more movements, and needs to be stopped down for best quality and coverage.
For future reference, if a normally good lens is sharp in the middle and really bad as it moves from the center, the very first thing to do is check for flipped element/s.
Re: Weird Coverage with Wollensak 159mm Velostigmat ?
My lens: 159mm f/12.5 Wollensak Anastigmat Extreme W. A. with purple partially circled "W" in a RAPAX shutter. I believe to be one of the last ones made. Actually found it as NOS (as far as I can tell was never used). Front rim distance to back rim is 1 3/16 inches (30.09mm). Absolutely covers 8x10 with a little movement possible. Can confirm that it needs to be stopped down for best sharpness and coverage. Aperture scale goes from f/12.5 to f/45 but does stop down to an unmarked f/64. For me F/45 is its sweet spot. The aperture is half closed when set for the marked f/12.5 but opens up a lot wider (for focusing?). I always thought that it was actually the f/9.5 version but never could confirm that. Truth be told I use it a lot more on my whole plate which allows for generous front movements.