At the half of my shot (constantly moving camera) there is a focal length change. In my first tests **the camera is moving forward instead of zooming** into the scene. Is there a trick to automatically detect the focal length change? 

*Is it currently possible to reconstruct the camera from such a shot at all? Until now I only have found [this proposal](http://wiki.blender.org/index.php/User:Sftrabbit/GSoC_2013/Proposal), but I could not figure out if this is part of blender.*