Hi Paul.
I tried difference setting but the best one is this.
The difference between 14 to 24 can be corrected by adjusting the trim.
I have tried with Nikon 20mm f2.8, was more stable and much lighter but the quality and of course the wide angle of 14/24 is unbeatable.
Let me ask you about the D800, you can write to alessandroficano@gmail.com
Ciao.