My apologies for coming into this discussion late - and I have not read most of the thread - so sorry if this has already been mentioned.  The Octane plugin pretty accurately determines the camera position and fov for both the main Poser camera, and the dolly camera (the formula is different for each).

HORIZONTAL fov = 2.0 * math.atan ( ( FilmbackWidth / 2.0 ) / fl ) * 180.0 / math.pi

... where fl = the camera focal length.  FilmBackWidth is 26 for Main/Aux cameras and 22 for Dollys.

If you want vertical or diagonal fov, more calcs are needed - and I have the formula's somewhere.

The camera position for Dolly's it's the DollyX/Y/Z position.  For the main/aux camera it is 1.8 meters (not poser units) behind the DollyX/Y/Z position - where "behind" is the inverse vector from the view vector.

Paul

Creator of PoserPhysics
Creator of OctaneRender for Poser
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