10-22 and filter owners......vignetting.....let's lay this argument to rest

I have two 77 mm B+W CP filters - a standard thickness F-PRO and a slim filter. The standard thickness one does create some vignetting at 10 mm on the 10-22, but seems to be gone by 12 mm. It also seems somewhat unpredictable in terms of whether the vignetting is going to be visible. The slim filter causes no noticeable vignetting. This is shooting in RAW - I don't think the camera (T2i) applies peripheral illumination correction to RAW.