Just received the Nature brand Neutral Density filter today. It's possibly the cheapest Fader ND on the market right now, so I wanted to see what the quality was like. I picked one up to test on the Canon 85mm F/1.2 which requires a 72mm filter. The Canon 85mm F/1.2L is one of Canon's sharpest lenses in it's lineup. With the lens at 85mm on a Canon cropped camera, you're looking at quite a distance. I was expecting to see extreme softness, which some Variable ND filters can cause, especially over 50mm. This wasn't the case with this Variable ND filter.
There is some noticeable difference in sharpness, but not very noticeable unless you're really trying to nitpick, so not bad at all. It's definitely not as soft as my other Fader Filter which is very noticeable when zooming into a subject. Again, i'm asking alot since i'm putting it on an 85mm F/1.2L, but for any wide lens under 50mm, definitely a solid product that will yield excellent results. I'll be posting up some samples of the lens with and without the filter soon for you guys to check out, but i'm very happy with it and will be planning to get a few more. For now the Nature brand Fader ND can be found at this link: Nature Brand Fader ND Variable Neutral Density Filter