This photo shows the completed module (to date anyway !) with the IDAS Type IV UIBAR filter up front as an ERF. Next is the step adapter - used because I already had the M46 threaded aluminium adapter. Then the Ca K filter from the Ca K PST, then an adapter to 1¼" female nosepiece, and lastly the Baader 'U' 'venus' filter (which is screwed on to the camera nosepiece).