24-70L II + step down ring to 77mm + polarizer

[Cptn Rigo]

Hi Everyone!

I pulled the trigger with the 24-70L 2.8 II, so I bought his 82mm UV filter... however... the 82mm Kaesemann polarizer is over 200 dlls!!!... auch...

I already have the 77mm Kaesemann polarizer.

Someone has tried to use a 77mm filter with the 24-70L II with an step down filter adapter?

How bad is the vignette?

Thanks Everyone!