K&F "seem" to make reasonable quality products, and this ND filter fits the bill. You might think a dark piece of glass would be hard to screw up, but there are more ways to do so than you might think; irregularly tone or color probably being the most obvious. This little guy doesn't seem to suffer from either. It's evenly and neutrally dark. That said, I should point out that I haven't done any rigorous testing, mainly because, quite frankly, my photography isn't that rigorous. It simply does what it needs to do and for a reasonable price. Sure, if you wanted to, you could spend 2-3x more and get something equally functional, but wouldn't you rather spend that extra money a trip somewhere and actually use your camera? Of course you could also spend half as much and go to some really exotic local, but I'm pretty sure that if you did, you'd be disappointed with the images that cheap filter produced.
28/06/2019
Very pleased with this purchase, the filter has no color cast at all, and it's a true 10 stops filter as far as I can tell. It also comes in a nice leather pouch, a nice touch.
03/06/2019
I love K&F 100*100mm Filters, the best quality glass.
07/05/2019