<p>Hi, I have a Proxar filter with Voigtlander Zeiss Ikon Bayonet 50 mount. This is a two-prong mount, not to be confused with Hasselblad Bay 50 mount which is totally incompatible. I want to mount the Proxar on a 39mm-threaded lens front, either directly or through an intermediate step-up ring. Any ideas?</p>