Has anyone opened up an Avenon/PasOptik,Kobalux
21mm viewfinder? I just received one (NOS in the box with its front and back cover) but it has a little haze inside. I'd like to clean it but am having a tough time getting into it. It looks like the front ring should just unscrew but I can't budge it. Any tricks or tips I am missing?
I have other 21mm viewfinders but I like the magnification on this one.