Isn't that a one way or a 2 way mirror, I was thinking about that, and I also saw someone selling a mirror protective sheet for the iPhone, which works similar to the teleprompter mirror, when the iphone LCD backlight is on you can see the screen contents, but when the backlight is off, it will act like a mirror and you can see your own face or whatever is around you in it.
Have a look at this link https://3dvision-blog.com/3983-building-a-very-cheap-diy-beam-splitter-3d-camera-rig/ and the guy uses the iPhone screen protector for stereo 3D, the difference with his setup is that one camera is behind the mirror and one in front of the mirror, so it works pretty well for him.
In my setup I have the camera behind the mirror, and what I need is the mirror surface facing the camera should be reflecting, for that I would need lots of light on the camera side, but also I want the mirror to be see through, but that extra light on the camera side would just make the mirror reflect and I won't get the see through effect, unless I adjust the brightness of the lights.
So I'm really not sure if a teleprompter mirror is a good fit for this setup, correct me if I'm wrong.
Agreed! problem is where do I find these kind of mirror's?.
By long lens do you mean "Telephoto lens"? Yes you are probably right, I did not initial drawings on the setup and I did some calculations with a wide angle 60 to 70deg FOV mobile phone camera, I had difficulty in getting the image fitting on to the mirrors because of the wide angle, the mirrors were taking a small portion of the final image.
2 cameras, well wouldn't we need to synchronise the cameras then, and therein lies the issue to get both camera's perfectly in sync.
Thats the most amazing resource you have got on stereo 3D, probably the best there is on the web.