I have a horseman FA. I also have a foldable horseman reflex viewer but it does not have the adapter plate that attaches the viewer to the camera.
1. If anyone has this adapter plate they wish to sell -- I'll buy it.

2. Do the other horseman viewers such as the direct binocular viewer or the non-foldable reflex viewer use an adapter? Are they interchangeable?

3. Any other ideas or solutions appreciated.