Important to note is to this bellow I use the PROshift+ which enable the camera to be moved 10 mm to the left and right. The resulting images I stitch as panorama. If I am not mistaken the size of the image circle would be 44xx36mm (I haven't tried horizontally which would yield 56 x 24 - knowing myself I will give that a go one day..... :-) ).
With my S-Planar 100mm f4 (for Contax bellows) I always use a polarization filter and lens hood, which at least in some case is very beneficial. I'd like to do the same for the 74mm.
The lens has no filter thread, but I found a rubber table leg covering which fits very snug on the 74 and my thought was to glue a step up ring to this. That would than fit a pol filter on top of which a Heliopan (there are much cheaper alternative, but I like these) lens hood can fit.
What I can't get my head around is what dimensions these parts should have, without causing vignetting. I could obviously step up to 55mm and use the hood & filter I use for the 100mm, but a smaller diameter would be more practical.
Below a picture of the setup and an experiment with a flower.

