The interior tube isn't threaded.
Also, don't forget that the tele and wide conversion lenses come with the theaded 55mm tube extension, so you get the ~$15 tube "free."
I wish to purchase a UV Polariser and a lenshood for my newly
purchased S602Z is there any valid reason why I have to buy a (very
expensive) metal tube to take 55mm filters when the thread on the
front of the retractable part of the lens is 43mm (approx)?
I understand that the filters should not obstruct the lens from
retracting but it appears after a test the filter I have does not
cause any obstruction.