Denosha, thanks. I think the Z-PRO Series isn't really necessarily afterall (for this lens). The vignetting (when the holder is properly aligned) is really minor to warrant the cost difference for the Z-PRO series. I think vignetting can be even better controlled if focal lengths starting from 11mm or 12mm onwards are used instead of 10mm; to compensate for the 1 to 2 mm lost, just step back a few steps. 
