These are OK if you have a zoom lens on and that it's zoomed to have or more of it's max magnification. Since this is essential one polarizing lens rotating against another, there will be spottiness and distortion the further out from the center frame you go, in most cases. Not too bad if only using the center 50% or so of that filter when zoomed in.
25/10/2019
There are way too many ND Filters out there, but if I can recommend one just to start, this is perfect.
30/07/2019
Intéressante formule pour un filtre ND (Densité neutre) il combine toute une gamme de densité en un seul filtre. Intéressant et économique.
19/04/2019
...it flairs too easily with any light forward of 180 degrees, making a lens hood mandatory... but you cannot use a standard lens hood with a variable ND filter of this design. Other than that, the colour shift is neutral as it should be, and the range is very good. I predominately use this for video work and its is performing well in that capacity. I have not tried it with long exposure still work, but experience suggests this is not for that kind of photography. If you want to do long exposures, invest in a good Lee or similar square photography filter, not a circular variable like this.
15/04/2019
First variable ND filter purchased (all others I have had have been static) and what a difference it makes!So easy to move around, and not having to carry more than one per lens is a real space-saver in the bag!I've experienced no false colour or the infamous X on any images (although I don't use this all the way closed!)Comparing it to a friends premium ND (I won't mention the brand), I could not see a difference at all in image quality. However, the premium ND was a bit stiffer to move around, so it felt like it would stay exactly where left. The K&F one does feel like it may loosen up over time, although this hasn't happened yet a few months in!
28/03/2019