Review on K&F Concept 77mm ND8 (3-Stop Fixed Neutral Density Filter) ND Lens Filter - Premium 28-Coating HD Hydrophobic Ultra Slim Nano-X Series Filter for Camera Lens by Seth Gomez

The K&F Concept filter comes in a round protective case which appears to be versatile as it fits many filter sizes. The filter itself is of high quality and has knurled handles that are on opposite sides of the filter to ensure a good grip. The filter is very light thanks to the aluminum frame and thin glass. The filter has a very low profile to minimize vignetting, but is still threaded to accept other filters. The aluminum frame is also the biggest weakness of this filter. Unlike my other ND filters with brass frames that snap on and off easily, the K&F's lens threads seem so unusual that it frays and binds horribly when trying to attach it to the lens. I was able to partially screw it onto the lens to test it but never fully fastened for fear of damaging the lens. In terms of optical performance, it reduces the light by the indicated three stops (1/8 reduction). The MRC coating on the filter is easy to clean and I didn't notice any significant signs of glare, so the coating does the job in that regard. Many of these types of filters impart a color cast depending on the materials and coatings used - for example, B&W Schott glass is known for its yellow cast. The K&F filter is very neutral in this regard - it does give the image a blue-green tint, but it's so weak it's almost invisible. The most ND filter I own is the Breakthrough Photography X4 ND filter and this one is almost as good but only 1/6 the price. I really wanted to like this filter. It has decent optical performance and a low enough profile to be used as a stack filter. Unfortunately, the threading on my sample renders the filter almost useless, which isn't a good thing at all costs. I would give this filter 5 stars for looks and 4 stars overall if the filter threads were ok. Filaments aside I think this filter works quite well optically so if you can get a good sample it's a fantastic deal.