K&F Concept 67mm Variable ND Filter ND2 - ND400 Adjustable Fader Neutral Density, Ultra Slim Waterproof Multi Coating Optical Glass Lens Filter (Nano-K Series)

Well packaged and delivered the next day. The filter itself feels to be of good built quality with a metal frame holding the glasses in place. The action to adjust the stops is smooth. I bought this mostly to save some bag space so I'm not having to either stack and carry multiple ND filters.Considering the price, the image quality is reasonable. I did not experience the dreaded X from the graduated filter. You can see some product and test images I did at home to test the product. ( the camera settings remained the same throughout the test images with adjustment on just the ND settings).

Useless. sent it back for a refund. didn't really change then made a crossover of the two lens. see photos.

I wanted a lens you could use for a 30 second exposure, it doesn’t do the trick. The picture is uneven. Also the glare from lights if doing nighttime photography is problematic. I had high hopes for this product

The lack of end stops is annoying as the filter just turns past min/max points making it impossible to accurately set without looking at the dial. A few others have mentioned the colour cast and I thought it'd be easy to correct by adjusting the white balance, but it's not. It's not just that the image is warmed, it has a mix of cuts across the colour range so would need a custom curves layer to be applied to correct it all out and get back to true colours. However, that's not possible because the cast isn't consistent across the whole field of view so it's not possible to get back to accurate colours across the whole shot.Neutral Density is supposed to mean NEUTRAL. This is SO FAR FROM NEUTRAL it's not worth using. Returned for refund.

I understand how these filters work, you have 2 polarising filters and as you cross them they get darker.The problem with this one is that as they het darker you send up with a huge dark X shape created by the filters. It is effectively useless. A complete waste of money.

This filter works well up until the 'MAX' setting, at which point the dreaded "purple cross" effect appears. If you take it back a few notches it works fine. I'm quite happy to put up with this as I knew this was likely to happen and I can deal with it, if only for the sheer convenience that it offers.

To be honest this is a medium product. I would not use this in important projects. It's a good product to play around with if you don't mind adjusting the colours in Photoshop.

Not something I use often, but it is a no fuss solution. Colour shift is negligible, though when I do use it I tends to be for black and white.