Could it be off a binocular?
Yes.
That's why I mentioned the off-standard lens sets I observed on some of the early 2/3" Vidicon security cameras.
Looked up & verified .625 is D mount. Adapter plate to C mount available. Mounts to Sony Cameras available.
It was indicated for 8 mm film cameras which I never used.
Similar looking examples available on Amazon.
If you want to reply, then
register here. Registration is free and your account is created instantly, so you can post right away.