https://petapixel.com/2017/12/13/nisis-new-variable-nd-filter-no-x-effect/
NiSi's Latest Variable ND Filter Avoids the X-Effect Problem | PetaPixel
May 19, 2022 - NiSi has announced a new variable ND filter called the Pro Nano 1.5-5-stop Enhance ND-Vario. One of the filter's features is that it says has no dreaded
variable nd filterthe x effect