slr magic hyperprime 12mm - w 77mm adapter can i stack 2 filters w/o vignetting?

[texcam]

I want to create a DIY adjustable ND filter by stacking a Marumi DHG Super Circular Polarizer and a linear polarizer on an 58-77 adapter. Will this cause vignetting on this lense? Anyone tried this?

[Francisco Rios]

Hi Texcam, I have the 12 mm slr magic.
I use a 58-72 mm adapter for a Variable ND. It's ok, but I can't stack any other plus filter because it "vignentts".
It works only with one filter on it on a 72mm adapter.

If you want to stack your DIY variable ND, at least you will need a 77 mm adapter.
Hope it helps.
Cheers...