Question on Rodenstock 28mm Digaron-S and Center filter

[Paul2660]

I am looking to find out more information from other photographers who have used this lens on a P65+ or any 56+MP back.

From the literature on Rodenstock's site, they don't reference a separate center filter for this lens, as they do for the newer
W Series 32mm, and the S series 23mm.  I would prefer not to use a center filer but right now I can't even tell if Rodenstock
makes one for the lens.  

Also can anyone confirm if this lens is retro focus in design?  

I would appreciate others feedback on their results with this lens and if they are using a Center filter and what brand? (Rodenstock or other)

Not interested in shifting as much as just using the lens center on and vignetting.  

Here is a link to Rodenstock's site where they talk about their new "digital" center filters which are a new type of make, but they don't
list the 28, however they do list the 23 twice so it may be a typo.

http://www.rodenstock-photo.com/mediabase/original/Filter_brochure_Center_2010_CD_Engl_10184.pdf

Thanks
Paul Caldwell

[Paul2660]

Actually I would be interested in any feedback on photographers using this lens on any back.

Again the Rodenstock 28mm S lens, with the 72mm front filter threads. 

color shift not shifted and shifted to 5mm
Vignetting from F8 out
Corner sharpness from F8 out
Filter use, CLPL and ND

Cambo, Alpa, or Arca

Thanks
Paul