Canon 10-22 - diopter- vignetting

i'm still trying to find a definitive answer whether i need a +2 diopter with my 10-22 in an Aquatica dome

is there any brand(s) thin enough to have minimal vignetting (i've found a significant difference in thickness of filters and diopters in the past)?

i'm still trying to find a definitive answer whether i need a +2 diopter with my 10-22 in an Aquatica dome

I asked Aquatica that question for a 40D and EF-S 10-22 and the answer was No, diopter not required.

Aengus