I recently purchased a Variable ND filter from Singh Ray for my Canon 24-70 f2.8 mark ll lens. On my Canon 5D Mark ll (FF) i get significant vignetting when I shoot wider than 35 mm. Singh Ray does not make a thin filter for the 82mm threads. My options are to return the filter and explore other options including a fixed filter or other brands or keep the filter and just deal with the vignetting in PP. How have others dealt with this problem?

