While not considered as good (and certaily slower) than the 3.5cm/f2.5 - I do have one of the 3.5cm/f3.5's
Unlike the faster lens, the version I have does not have any filter threads in front of the f/stop ring. The only threads are recessed way down just in front of the glass.
I prefer filters. Anyone know what size diameter filter would "fit" way down there? Is it possible to even put a filter there - although why else would Nikon have put threads down there?