Is there a way to ensure that the camera is on level when mounted to the scope?
I ask because I do not see any freely-rotating element anywhere in my planned setup: scope's t-thread - this adapter - 46mm adapter on camera (Panasonic LX3)
And if not, how far away from level can it get?
You're absolutely right, there is no lock down ring on the adapter. If you don't have a lock down ring on the adapter on your 'scope side, leveling can be an issue. The first time I used the adapter, I "encouraged" a level, tight fit, and had a devil of a time getting the t-mount off the camera body later. Lesson: don't over-tighten! What I do now is to adjust the combination of the t-adapter and the scope adapter to achieve level which, while not as tight as I might like, achieves the objective satisfactorily (you may have to adjust from time to time to make sure the camera maintains level). A DIY solution is to insert a rubber washer between the scope adapter and the scope body which may give you flexibility to achieve a tighter fit, but as the former solution has worked for me (if not ideal), I haven't tried it. Hope this helps. JAY