Crepuscular Rays is the word I was looking for. That could possibly have helped to add convergence in support of the subject. But then it would probaby still need something at the lower end.
The unnaturally light part may well be a result of blending. The overexposed frame becomes white at about there. On the other hand I find those new "digital" lenses to be excessively ...uhm ...contrasty, hard, slap-in-the-face. Combined with the vignetting it may also have been somewhat exaggerated. That's of course no excuse to not compensate for it in post-processing...
