lee filter polariser issue

[mickeyt]

hi..wonder if u can plse help..ive bought the lee filter system with the expensive b + w 105mm polariser on the front ring attachment..i use the canon 16-35 lens for wide lanscape shots...ive found vignegretting on the sides...how i can prevent this plse or reduce it?..i want to keep the wide angle as wide as possible without having to reduce my picture scope.

i will want to use other lee filters with the polariser
cheers

mike