Glad you like it, hope you can put it to use 
If you make any major changes in camera location, moving it much closer mainly, this system runs into problems.
Hi Aurrin,
thanks a lot for the blend-file!
Works like a charm and seems to be the “implementation
of your math formula in mechanics” … 
I will try both solutions, both are working fine!
Keep blendering and thank you all for the support!
mcc