Because K&F Concept ND2-ND400 filters adjust the amount of light that can pass through polarizing glass, color cast cannot be avoided with all variable ND filters on the market. However, K&F Concept variable ND filters are made with the best coating technology that reduces the effect of the polarizing film on the image color. *Based on our professional test, the color cast of K&F Concept ND2-ND400 filters is around 290,000 while the industry standard is 500,000.