K&F Concept Square Filter Holder System (X-Pro series) review: a comprehensive starting point with an interesting design

K&F concept is well-known as a budget accessory brand that often produces products of a higher quality than their prices might suggest. And despite the likes of Kase, Lee and NiSi Filters dominating the square filter market, K&F Concept produces impressive glass filters at a considerably lower cost.

The K&F Concept Square Filter Holder System X-Pro series is a comprehensive professional filter kit to get you started with four filters and four adaptor rings included. The kit includes a square filter holder, a polarising filter, an ND8, an ND64, and an ND1000. You can also purchase ND grads separately, but you will need to either purchase the K&F filters that come with the required frame or purchase the filters and frames separately.

The X-Pro series differs from the competition in that the filter holder is wider than the filters themselves, which means the filter frames are an integral part of the system. Filters can’t be used without the frames, but the three included ND filters come framed and ready to go, so no worries.

The advantage of the frames is that you can handle the filters without touching the glass at all, using the frame edges or the tabs at the top and bottom. This approach makes sense in many ways, but it’s not perfect, and we’ll discuss that later. Find out more about photographic filters with our guides to the best filters for photography, the best polarizing filters and the best ND filters.

K&F Concept Square Filter Holder System X-Pro series: Specifications

K&F Concept Square Filter Holder System X-Pro series: Price

The K&F Concept Square Filter Holder System X-Pro series is packed with everything you need to get started with the filter system. Except for ND grads. It’s also extremely well priced at $330 / £269 / AU$528. What you get in the kit is comprehensive, and you can purchase 100x150 ND graduated filters separately to build your ideal system. Other kit combinations are also available.

The quality of the optical glass used for the filters is excellent, although K&F Concept square filters are less expensive than competitor brands. You will, however, have to purchase filters and frames separately, or purchase K&F filters that include the frame that’s required by the filter holder. In both cases, the filters and frames remain less expensive than the competition.

K&F Concept Square Filter Holder System X-Pro series: Design & Handling

The K&F Concept Square Filter Holder System X-Pro series kit is extremely well made, with the main body of the holder being constructed of aluminium; two plastic filter slots are screwed onto the front. And while looks are secondary, the orange accents against the black holder look great.

On the back of the holder, you'll find an orange metal wheel to rotate the polariser to achieve the desired effect, and an orange metal locking dial to secure the holder to the 67, 72, 77, or 82mm adaptor rings.

The ND filters don’t have a gasket to block light entering behind the filter; this is on the front of the filter holder itself and works equally well with no light leak. One thing I would say here, as a landscape photographer, is that I prefer three filter slots because I sometimes use three square filters at once. This approach to the gasket may sound odd, but when you use ND filters with ND grads, you should always put the ND filter in the rear filter slot anyway.

The polarising filter sits behind the square filters, within the holder body itself, using a unique arm that opens up to insert the polariser, and is then pushed down to hold it securely in place. The filter holder is just 12mm thick, which helps to avoid vignetting. The advantage of the rear positioning of large diameter polarising filters is that you can use ultra wide-angle full-frame lenses, such as 16mm, without vignetting.

As previously mentioned, the filter frames allow you to handle the filters without touching the glass, using the frame edges or the tabs at the top and bottom. The disadvantage for me is that the frames are quite a tight fit in the holder, so you have to push them out of the holder rather than pulling them, with the latter being more logical and convenient. Pushing them out is easiest when you remove the filter holder from the adaptor ring/lens.

Pulling the filters out can result in the frame coming apart since they’re made of two clipped-together sections. This certainly isn’t a dealbreaker for the system, but it’s something you might want to consider. I didn’t try loosening the screws that hold the filter slots in place, so this may allow for easier insertion. Also, the slots may naturally allow for easier filter insertion over time as the holder is used more.

The kit comes complete with a leather box-style case that keeps everything safe and in place, with dedicated compartments to store and carry everything. Only the adaptor rings sit behind the filter holder, in the larger section of the case, rather than having their own storage area. A nice touch is that you can pull an orange cord to expand the filter section of the case to reveal the ND filters in a stepped formation for easy access.

K&F Concept Square Filter Holder System X-Pro series: Performance

The filters are made of imported Japanese AGC Glass with 36 multi-layer coatings and double-sided polishing technology. These coatings make the filters resistant to water, scratches and oil. In rain and with waterfall splashes, water does typically run off, but like other glass filters from competitors, you get the odd droplet that doesn’t run away. A quick light wipe with a lens cloth solves the issue.

I dropped one of the filters on my desk as I inspected it as I write about performance, and it didn’t suffer any damage at all, despite clanking around for a second. The frames will provide a degree of protection when dropped, and K&F Concept claims that the frames can offer protection when filters are dropped from a height of up to 59in / 1.5m. Of course, this will always depend on the angle in which the filters fall and hit the ground.

I didn’t test oil resistance because any sane photographer will keep their filters away from oily residues; it’s ingrained to be this way for fear of an expensive mishap. However, the potential for this and other debris to be easily cleaned away could be useful on rare occasions, and welcomed if it does indeed work as claimed.

The glass used to manufacture the filters is undoubtedly of a high quality, with clear and sharp images possible with their use. Glass filters are head and shoulders above resin filters, which are nowhere near as optically clear and can suffer from areas of blur, as well as suffering more from scratches, even when handled with care.

The colour casts produced by the filters are also minimal, although the ND64 ND filter looks slightly green while the ND1000 looks slightly yellow and magenta. This is common for ND filters, despite being supposedly neutral, and this can be easily fixed in Adobe Lightroom and similar software. Even if you shoot JPEGs rather than Raw, you can use the Camera Raw Filter in Photoshop to fix white balance and other colour issues.

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When capturing the example images to show the effects of the filters, white balance was set to daylight and no colour adjustments were made during processing to allow you to see any colour changes. The first shows no filters, the second just the polariser and the subsequent photos show the polariser used in conjunction with each ND filter. This allows you to assess any colour shifts compared to the unfiltered photo.

Moving back to the filter strengths, the ND8 offers a 3-stop exposure reduction, the ND64 8 stops and the ND1000 10 stops. This provides landscape photographers with all the ND filters they’re likely to need, and I don’t say this to make the kit sound perfect. In my square filter kit for landscape photography, I have just these three ND filter strengths alongside my ND Grads and other more specialist filters for night photography and video capture.

K&F Concept Square Filter Holder System X-Pro series: Verdict

Many square filter holder kits simply come with a case, a few adaptor rings and a polarising filter. The K&F Concept Square Filter Holder, on the other hand, also includes four adaptor rings and three ND filters to get you started. Build quality is excellent, while the quality of the filters can’t be faulted. The only caveat is that the system requires frames to be added to 100x100mm and 150x100mm filters to fit into the holder. Filter and frame combinations are also available separately.

The quality of the glass is impressive, and the system as a whole works well except for the stiffness of the filter slots and the fact that there are only two, rather than three slots. What’s most impressive is the price of the kit, since it’s extremely affordable for both what’s included and the overall quality of the individual components.

Alternatives

The NiSi JetMag Pro Landscape ND Kit is a magnetic filter kit where the filters attach magnetically to adaptor rings. This type of filter system is much smaller and lighter than traditional square filters, and NiSi Filters is also widely known for its excellent quality filters.

If you’d prefer the most minimal ND filter solution available, the budget-friendly Tiffen Variable ND filter could be exactly what you’re looking for. Variable NDs can be rotated to adjust the light-reducing strength, but they often produce an unsightly X effect at high strengths.