Originally Posted by Nige
I have a 2X convertor that the glass screws out (as a feature, not just the way it's built) and turns it into an extension ring!
Yep, the Kiev 60/88 TCs do that too. I saw one on fleabay once being sold as a TC, but thankfully i noticed that the glass was clearly missing in the photos...
An awful lot of electrons were terribly inconvenienced in the making of this post.