Challenge number 1) The K&F Concept 77 mm Variable ND filters I purchased arrived later than promised and I was not able to use it for my 9 day photoshoot. Challenge number 2) It fits on my camera lens but needs time and patience to attach to the lens but it does fit. Challenge number 3) No positive stops, no detents to let you know how far you've gone (my ND filter 1.5-10 stops). In addition, if you are invested in using your lens hood while shooting, it won't fit with these ND filters. I'll be using the ND filters on my next photoshoot and will submit an update to my review.

use this for my cell phone for filming. Works well for that. Not sure I would use it for my digital camera. I have a much better set of filters for that. For the price works very good.

bought this to use on my new lens that has a wide f-stop, .95. Work well for me, but I'm not a professional any longer and was looking for an easy-to-use filter.

Strong solid build. Colors look good too.

love this project. No real distortion. It’s about a two stop difference. Will purchase for my other lenses!

It's exactly what I needed when the outdoor shots are too bright. I'm also using this the eclipse In October so I will update this review after that event.

The filter works best if you have a lens that is greater than 35mm. When the lens is too wide angle is when you get the X looking area

Good product.

seen another photographer and his work I had to get my hands on them

K&F Concept's range of filters have never let me down and neither has this variable ND3-ND1000 ND filter. This filter maintains accurate color throughout the entire range unlike other filters I've used, which is a huge plus since it saves me time in post by not having to mess with color correction. There is no dreaded "X", even when I intentionally went too far. While I'm not sure the stated range is entirely accurate, it is close enough and provides a ton of functionality, especially given the low price point compared to other filters that offer such a great density range. I don't experience any vignetting with this filter, which isn't as slim as others I've used. But I rarely get vignetting when using the 18-140mm lens that I tested this filter with so my experience may not be applicable to different lenses. Stops are clearly marked on the filter, and the adjustment is smooth with a little resistance that offers good control while shooting. That said there is one thing you should know about this filter - YOUR LENS CAP WILL NOT FIT. I wish they included a lens cap with this filter or at least stated this clearly in the description, because you'll have to either print a new lens cap or buy one that will fit over this filter. For the 67mm filter, you'll need a 72mm lens cap. Overall this is an excellent value for a high quality filter. I doubt you'll find another variable ND filter with this range and at this quality for a lower price.