Thank you Alex. That empty barrel covering the lens as you describe is interesting. The black inside seems to be due to the front of that barrel most probably protruding a bit over the lens assembly.
I just realized that I overlooked one page on the FP-projector manual. There it is described to take off a barrel covering the lens assembly to attach the zoom converter to the front of the, now naked, lens assembly. That explains my weird "empty barrel in the zoom converter box" find. Nearly...
Nearly, as my barrel has at its back a female thread wider than the inner cone of the barrel. This is screwd to the base of the lens assembly. How can it be pulled over that assembly, with the front of that assembly still bearing a male thread of the same dimension (to accept the zoom converter) ?
That would not be possible.
But I have to admit this all is of pure academic interest (other term for curiosity) but of no practical means to me...
Last edited by AgX; 08-18-2013 at 06:49 PM. Click to view previous post history.