K&F has been around for some time and they're a great go-to choice for value to performance. This review is for their variable ND3-ND1000 filter (1.5-10 stops). K&F does make more premium filters than this particular one, so this filter isn't their best, but it's still good. Build quality is fantastic. The inner stationary filter has two areas of knurling while the outer rotational filter is smooth. On the edges, you'll see lasered markings indicating minimum, boxes for stops, maximum, and an arrow indicating where you're at. Though this is somewhat useful, the filter doesn't always index on my lens so that is easily shows these markings. Furthermore, there aren't hard stops for the outer filter, so you can rotate it continuously. As you rotate through the full 360 degrees, you'll go through 2 full rotations of the minimum to maximum variable effect. Optical quality is on par with most of their other filters. Since you can rotate all the way through, and because this variable goes up to 10 stops, you'll run into the X effect towards the deeper end. When I tested my 77mm filter on my 24-70, it wasn't immediately obvious on the camera screen but became more apparent once I imported the photo. The filter does live up to its density claims though as I was able to achieve up to 10 stops of change. Overall, the variable ND3-ND1000 filter (1.5-10 stops) by K&F is a fantastic buy below $60 and provides great value for its performance. I've long eyed the variables by Tiffen and B+W and PolarPro but at 2x-5x the price, I couldn't justify it without even knowing if I truly needed a variable ND. If you're just getting into using ND filters and you want to play around with an entry-level cost variable that will last you a while, I strongly recommend the K&F. It runs into the same X issue found in nearly all variables without hard stops.

The filter was able to attenuate my laser alignment beam in my optical cavity setup. It was a better solution than using a radial variable ND filter which costs over $400,00 and then a $125 mount which is crazy. I did it for under $25

Very nice, clean variable nd filter!This is the perfect md filter if you are running and gunning! No need to change filters over with this one.I find it so helpful when I'm wanting to capture long exposures and when I'm filming this is a god send.It's nicely packaged and comes in a little carry case with a branded cleaning cloth.I'm very happy with my purchase and it does what it says on the tin! A very high quality Nd filter!

This is my first variable ND filter, so I can't compare it to another filter. I used this filter during a beach photo shoot in early afternoon harsh sunlight. I was very happy with the results and will continue to use it and recommend its use to others.

Excellent nd filter. Crystal clarity and has a very smooth function. Exactly what I wanted to lower my exposure for waterfall shots and light trails.

Works exactly as expected. Anyone complaining about the "X" on their images is not reading the instructions. Works great, and is a great entry level filter for anyone looking to experiment with ND filters.

Filter: 46mmLens: Olympus 25mm 1.8Camera: Panasonic G9 16mpColor cast: Fairly significant magenta cast, particularly as you stop it down more.Vignette: Not too bad until you get close to the ND400 end, and it's not an even vignette either - at least on this lens it's stronger in the upper right.But, it's an ND2-ND400 variable ND for less than $50 - tough to complain too much due to the convenience factor.Images: Uploaded five images, from minimum (ND2) to maximum (ND400). The histogram in the upper right shows the cast pretty well.

I've always struggled with situations where I wish I could use my variable ND filter with my polarized filter which until now, it was impossible. This filter solves my problem with really good picture quality.