I had a custom 2 inch adapter made from a forum member first link below and I can screw a filter in and a sct f6.3 reducer the other end.
2nd link is a photo.
http://www.iceinspace.com.au/forum/s...64#post1460864
http://www.iceinspace.com.au/forum/a...hmentid=249061
Regards
Kon