The components. Clockwise from top left:
* Sigma 52mm clip-in hood with clips removed and inner edge relieved.
* 52mm clip-in lens cap.
* Retaining ring and glass from Leica E39 UV/IR.
* Brass body of adapter with 52mm front thread provided by sacrificial 48-52mm step up ring. Main outer diameter of adapter is close fit inside the 'petals' of the lens.
* Clamping ring (close fit outside the 'petals') and M3 capscrew with Allen head turned down to fit.
CV15 adapterphotographic accessories