Dear all sifu-sifu here, I have a tokina 11-16mm UWA lens and I want to try ND filters for those long exposure landscape photography.
At first, I am looking for variable ND filter since it can be adjusted according to different density, which sounds more economical since I have a limited budget.

However, as far as i know, variable ND filter is not recommend for UWA lens as you can see its frame/vignetting.
Some people say need to get a bigger variable ND filter so that you wont see vignetting, using step up ring i think?
Or get those square filter with holder would help?

If get a fixed ND filter, is there any level (stops) of ND filter that is "fit-for-all-use" or provide versatility? (common ND used)

Please enlighten me. Thanks!