K&F Concept 37mm ND Filter Variable Fader NDX Neutral Density Adjustable ND2 to ND400 Lens Filter Kit + Cleaning Cloth for Cameras Lens

Good

N/A

I m happy about this 10 stop ND filter it’s good for long exposure photography

Wide diameter and easy to adjust. Comes in a protective box for transporting it.I fancied trying some long exposure shots with my smartphone. I already had bought fixed filters but there was no adjustment to them without shooting through several layers of glass. Thought I'd try this one as it was adjustable. It's like having two polarising filters mounted together and is infinitely variable from light to very dark just by twisting the frame.It does take a bit of fiddling and post editing to get some natural colour back, but it did what I wanted it to and am waiting for some better weather to spend a bit more time tatting with it. Its is big enough to cover all the lenses on the back of the phone with room to spare for hand movement though you do need to hold it very close.Obviously a tripod is needed and a steady hand is helpful.It was suitable form my needs and I recommend it.

If you're photographing macro, jewellery, insects, etc, and you need the flash really close you're going to have really overpowered flash usually, and need a ND filter so you can stay at around 5.6 and avoid diffraction and then stack, and with the lights that close to the lens you'll need a lens hood to avoid flare. You can't do both with this filter.

Unless you're looking for a huge shadow in your photography then I'd leave this well alone, I risked it as I like the quality of this companies tripods so thought these may avoid the dreaded darkened X in the photo.At all but the lowest settings there was some sort of shadow in the picture, making any shots unusable, luckily I experimented before taking it away on holiday

I love k &f concept filters they are very well made of quality materials I no longer look at other brands as they are priced well also this is my 4th purchase of their filters also normally come in a well made pouch

They do not work with lenses with a focal length shorter than about 100 mm. The filters have a severe flat field problem with shorter focal lengths. See image below of a 'flat' blue sky. I beleive the problem is either due to the 2 layers of glass or else an impact of the dual polarisers which is how these work. Compounded by the angle the light goes through the filter with wider angle lenses.