Hi everyone, I'm looking to buy Grad ND/ Big stopper filters but got stuck with the system choice. Can you use Seven5 system at its maximum (2 filters with CPL) with Olympus 12-40mm at 12mm with no vignetting? I asked some shops and they said to be safe I should go with 100mm system (of course, more expensive). I did even ask LEE and they said they are not so sure. They willing to refund if I end up buying and got issue though. Anyone have a real world experience? Thanks for any input!