This is the third K&F Concept filter I've owned, and I'm delighted once again. I think this brand has a curious thing going for it: their cheaper products aren't particularly noteworthy, but their mid-range and high-end products are incredibly well-made. I tried out this variable ND filter for the first time this afternoon, and it was fantastic.

I've been using it since 3 p.m. at the yacht club, in full sun, and it's been incredibly useful. As a father who takes far more photos during the day than at night, I needed something like this. I always shoot in aperture priority, so by simply rotating the filter, I can play with the exposure and maintain a shallow depth of field, which I love for portraits. And although I didn't record video today, I know it's going to be great for me too because I always record at 24 fps. You know, because of the famous 180° rule, you have to set the shutter speed to twice the frame rate (that is, 1/50 in this case), and without a filter, that's impossible in bright sunlight.

In terms of build quality, it's a 10/10. I have filters from more expensive brands, and this one is on par with them. The glass is super clear, with no strange color cast or loss of quality. I was able to screw it onto my Black Pro Mist filters without any problem, which was essential for me because those filters don't come off my lenses. Just keep in mind that you can't screw another filter on top of this one. Of course, you can still put the lens cap on.

The density adjustment ring has just the right amount of resistance: neither too stiff nor too loose, it moves smoothly yet firmly. And the packaging... fantastic. A rigid, elegant box, and then a high-quality, vintage-style faux leather case with a magnetic closure and a secure mechanism to prevent any shaking from affecting the filter when it's stored. It's a real treat. Some "pro" brands could learn a thing or two from this; I have filters that cost twice as much and came in a useless little plastic case.

I'm giving it 5 stars because it's amazing and performs well in every aspect. Highly recommended investment if you shoot video or portraits in broad daylight.