K&F Concept Nano-Xcel Pro GND 100mm square filters review: top quality filters at a fair price

The best Graduated Neutral Density filters, also called ND grads or GND filters for short, are similar to ND filters, which act a bit like sunglasses for your lens, reducing the intensity of sunlight and enabling longer exposures. However, as the 'graduated' part of their name suggests, ND grads are part dark and part clear, so the darkening effect transitions gradually. They are most commonly used in landscape photography, where the sky is much brighter than the land beneath it, and thus help produce a balanced exposure.

GND filters come in different strengths to help you tame weak or strong sources of light, and also have hard or soft graduations so you can choose one that works best with your transition from light to dark – a dead-straight horizon will likely need a hard graduated filter, while a more ambiguous horizon with rolling hills, buildings, or mountains will need a softer graduation to help transition between your bright sky and dark foreground more gently.

K&F Concept is a Chinese filter manufacturer based in Shenzhen and is known for producing good-quality photographic accessories for photographers on a budget. K&F Concept’s X-Pro square filter system, which houses its graduated ND filters and filter frames, won the prestigious iF and Red Dot design awards back in 2021, and the filters are billed as a “professional filter system for a budget price” so I was very excited to get my hands on the XPro filter system, as well as the graduated ND filters, to put them through their paces. Here’s how I got on…

K&F Concept Nano-Xcel Pro GND filters: Specifications

K&F Concept Nano-Xcel Pro GND filters: Price

The list price for a single GND filter is $109.99 / £99.99. In terms of value, these K&F Concept filters are similar in price to other glass filters on the market. The filter frames cost $19.99, but come bundled with the filters, so you’ll only need to purchase these if you need spares. The filters also come with individual filter pouches with a drawstring when bought separately.

However, K&F Concept offers several bundles that offer better value for money, should you wish to purchase a GND along with more items for the system. One bundle that caught my eye includes a Soft GND8 filter, filter holder, circular polarizer, and ND1000, and costs $259.99, which will save you about 80 bucks if you were to buy those items separately. This bundle also comes with a large PU leather hardcase to help keep everything secure and tidy in one place in your kit bag.

K&F Concept Nano-Xcel Pro GND filters: Design & Handling

K&F's GND filters measure 100x150mm and come in Soft GND8 and Hard GND8 versions. There’s also a Soft GND16, but no Hard GND16 in the range currently. There are also Reverse GND filters (where the darkest part of the filter is at the center and is used for shooting with the sun near the horizon) in GND8 or GND16 versions.

The range also includes a circular polarizer (CPL), seven square 100x100mm ND filters (ranging in strength from ND4 to ND3200), four square Black Diffusion filters, and a Light Pollution Cut filter. Overall, there are plenty of options in the range to suit a variety of different shooting styles and situations.

The Red Dot design winner comes with a plastic protective frame, increasing the size from 100x150mm to 115x163mm, though there is a chunky tab at the top, bringing the tallest point of the filter frame to 192mm. The tabs are featured at both the top and bottom of the filter frame, so you can handle them without getting your fingerprints all over the glass – nicely thought out! The filters can also be stacked, and the tabs alternated, so they are easy to grab without them overlapping.

If you purchase the K&F Concept X-Pro Square Filter System (with the CPL, ND1000, and Soft GND8 filter), you also get a sturdy hard case that is big enough to accommodate the tall ND grads. The top flap of the case shuts magnetically, so it’s quick to access the filters and holder, while a nifty drawstring can be pulled to raise the filters out of the case at different intervals, making them easy to grab.

I don't recommend removing the plastic frames, as I did in my testing, even though they are available to buy separately. I couldn't put it together quite as tightly and snuggly as when it came new. However, if you wanted to remove the filters from their frames to use in standard 100mm filter holders, such as the LEE100 filter system, you could do so easily – even if that's not what the manufacturer intended.

Adapter rings are available for the K&F Concept XPro filter system in just four sizes – 67, 72, 77, and 82mm, so it’s a bit more limited than other systems on the market. You can, however, still adapt it to smaller lenses; you’ll need a step ring, which is a bit of a clumsy solution – I’d have rather seen more adapter rings readily available to fit the filter holder to smaller filter threads natively.

K&F Concept Nano-Xcel Pro GND filters: Performance

The glass filters are treated with a 36-layer coating on both sides, along with an anti-reflective film to tame surface reflections. I subjected the GND filters to various stress tests to see how they would react to water, oil, and greasy fingerprints. The good news is the filter has a hydrophobic coating, so water beads off it nicely, and most moisture can simply be shaken off. This also makes them really easy to wipe clean.

To test the anti-scratch coating, I first dragged the tip of a wooden toothpick across the filter surface, and it remained unscathed. So, to up the ante, I switched to a sharp metal nail and pressed it against the filter surface, gradually ramping up the pressure. I was seriously impressed, as even pressing hard with a pointy metal screw, I couldn’t inflict any discernible damage.

K&F Concept is also confident that the frame helps protect its filters and shouldn’t break even when dropped from a height of 1.5m, so, of course, I had to put this claim to the test. The filter landed directly on one of the large plastic tabs of the filter frame, which took a small scuff about 2mm in size – it didn’t shrug it off quite like one of the metal frames from the likes of the Cokin Nuances range, but did a good job at protecting the glass, which didn’t break or scratch as a result, so it was a pretty valiant effort!

K&F Concept’s Graduated ND filters are made from Japanese AGC optical glass. AGC, formerly known as Asahi Glass Co, is known for its high performance, precision, and light transmittance. In testing, I found the image quality from the Japanese glass to be very good and, to my eye, didn’t impact sharpness even when zoomed into 100%. It also didn’t introduce any additional chromatic aberration or vignetting, and flare was well controlled when shooting towards the sun, too.

K&F Concept Nano-Xcel Pro GND filters: Verdict

These K&F GND filters offer a lot of bang for your buck and will offer pretty much everything an amateur or enthusiast photographer could want. With brilliant features, like a 36-layer nanocoating for excellent water and scratch resistance, quality glass materials for stellar image quality, and an easy-to-use filter holder that has won a Red Dot Award, you get a lot of filter for your money and more features than even some more expensive GND filters and holders that I have tested.

Alternatives

Marumi Magnetic Graduated ND Filters offer good value, boast a novel magnetic clip-on system that enables them to be quickly attached to and detached from their holder, and will be a hit with those who like to work fast.

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If you’re looking for a compact GND solution that provides more control than a screw-in GND filter, you may be interested in LEE Filters' LEE85 Neutral Density Grads. They are part of a compact filter system that offers pro features but is designed for smaller cropped-sensor cameras.

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