The K&F Concept Nano-X Magnetic Filter Set - the only three filters that you will ever need
Photographic filters are obsolete…
… is one good example of a completely false statement. But some of them are considerably less useful than they used to be. There are however three filters that we will probably always need to have on hand. These are the three filters that are included in this very nice kit from K&F Concept. The Nano-X Magnetic Filter Set includes a UV (ultraviolet) filter, a circular polarizing filter, and a 10-stop neutral density filter.
The filters are magnetic and made of a high-quality German optical glass. The filters themselves are extremely thin and very strong. Most important of all they have advanced multi-layer coatings that both strengthen the filter and almost completely block reflections. They are beautifully crafted and a pleasure to use. I spent several days working with these filters and found the experience great fun. I am embarrassed to say that this was my first experience with magnetic filters. And I love them.
But before I get into the review of the K&F Concept Nano-X filters, I would like to cover some filter basics so that you can make complete sense of the comments in my review.
the combined power of an ND1000 and CPL
So, when K&F Concept decided to create a kit they did it right, and used the only three filters that we are ever likely to need. But what about warming filters, cooling filters, and graduated neutral density filters? Modern editing software has rendered most of those specialty filters redundant.
I need to interrupt myself here. This article is not intended for professional landscape photographers, who may have stumbled upon this scribbling by accident. No, this article is not for the sorcerers who shuffle decks of impossibly expensive glass panes and, while muttering incantations, slide them, cryptically, into the strange talismanic contraption that squats, all-seeing at the gaping maw of their lens. This article is instead for ordinary human photographers who dabble not in such dark arts.
Where was i? Yes, the filters. The ones we really need. Allow me to explain. Modern cameras do not need ultraviolet filters. This is because the sensor on a modern camera is not susceptible to damage by ultraviolet light. Also, many of our lenses already have ultraviolet blocking properties. The only reason to use an ultraviolet filter is to protect the valuable front element of the underlying lens. This is a theoretical consideration in many cases. Consider a top end Nikon camera and lens dropped from the top of the Half Dome, in Yosemite National Park. There is no ultraviolet filter in existence that we will be able to provide adequate protection to the front element of this lens.
Where the UV filter really comes into its own is when you're crawling through a sesbania bush in in search of an elusive Eudiagogus pulcher. You may be thinking, “Why, that will never happen to me!”. Maybe… and maybe not… But it happened to me, just two days ago while I was on my hands and knees searching for a sesbania clown weevil that I had seen dodge behind a branch. In getting to it, I brushed up against a barbed wire fence and one of the spikes dragged across my UV filter. I have never been so happy to see a filter destroyed. My macro lens survived the ordeal.
Clouds, slowed by a 10-stop ND filter
But you could be mistaken to assume that any old UV filter would suffice if all it's doing is protecting your lens. It's important to remember that anytime light passes through a sheet of glass it has to negotiate two individual interfaces. The light bends as it passes through each of these interfaces, and if the glass is not perfectly flat and perfectly clear it could create problems with your image. Using a UV filter to protect the front element of your lens is good practice, but you must use a good UV filter.
By the way, if I can achieve the same results as I can get with a filter, by editing the image in Photoshop or Lightroom, then I will do so. So the only way that Photoshop could take over from my UV filter and protect the front element of my lens, would be if I loaded the program on a laptop computer, and held the computer in front of my camera and lens at all times. This will work, but it seems a bit, well, cumbersome?
The second filter that cannot be emulated by Photoshop is the circular polarizing filter. This is an indispensable filter for most photography. It is uniquely capable of reducing the intensity of some wavelengths of light, without interfering with others. The video that accompanies this article will give several examples of how this can be used as a creative tool. There are certainly ways that reflections can be removed in Photoshop, but this is tedious and difficult to do well. A circular polarizing filter changes the sky in ways that a neutral density filter cannot. It increases the contrast and slightly boosts the saturation of the sky. A neutral density filter, on the other hand simply darkens the sky.
The importance of adding a CPL to the mix
In both of the above images a CPL filter is being used. In the top image the CPL is not engaged, while in the second image the CPL has been turned through 90° to provide maximum polarization. The effect is striking. This is an example of some thing that would be very difficult to emulate in Lightroom or Photoshop.
The CPL diagram
If you want to learn much much more about these various filters and how to use them, please watch this video. In addition to an in-depth review of the filters from K&F Concept, I also cover a lot additional material you may find helpful. I will summarize my review in a few points, right after the video. I will also have some links for where these filters can be purchased with great discount. But first, to the video:
Let me try to sum up the key points from my video review. I really like these filters. They are beautifully crafted, professional grade optical filters that work exactly the way they are supposed to. The magnetic rings are a new feature to me, and something I wish I had discovered sooner. The filters are easy to put on and easy to takeoff, yet they hold very firmly to the front of the lens. The magnets are strong, and sometimes a finger nail is required to pry them apart.
The filters come in a padded pouch with separate compartments for each filter. The zip on the package appears to be weather sealed. The pouch can attach to a belt loop and has a metal ring, presumably for attaching the pouch to a backpack or a belt loop. I would be cautious, however, about trying to access the filters while the pouch is hanging by the metal loop. It seems to have a tendency to try to flip over in the forward direction, and could quite possibly spill a filter or two.
The idea to provide an empty metal frame as an alternative to using the UV filter as the base layer, was very clever. I am OK adding a UV layer in order to protect my lens, but if it was the only option for using as a base layer, I would've been less impressed with the kit. It is possible to stack these filters and the magnets are quite strong enough to stack all four on the end of the lens. But there would be no good reason to do that. The most I could ever see using together would be the empty mounting ring with both the CPL and ND1000 filters. You could also use the UV filter in place of the empty mounting ring, but I see no point for adding an extra piece of glass to the filter stack.
Of course this is all rather unimportant if the filters do not function as intended. But they most certainly do. The UV filter is thin, very hard, and demonstrates no tendency to flare, even under difficult photographic conditions. The profile of the filters is very low, allowing most of the filters to be used without any vignetting, all the way down to about 24 mm focal length. Problems begin when you select shorter focal length lenses. While it is still possible to use the mounting ring and a single filter element as low as 16 mm, adding a second glass element to the mix, usually results in some vignetting. In most cases when it occurs, the vignetting is slight and could easily be cropped from the image. Only when all of the filters are stacked together does severe vignetting overtake the composition.
The circular polarizing filter works exactly as intended. When it is unengaged there is approximately one stop of light loss. When fully engaged the light intensity is dropped by almost 2 stops. This is quite normal for a circular polarizing filter. One thing I really love about the CPL is that the magnet offers just enough resistance to rotation of the filter without being stiff. It is very easy to adjust the CPL with the tip of a finger, even when it is deep within a lens hood. Talking of lens hoods this is one definite weakness of the filter set. In many of my lenses, it is not possible to apply the filters and the lens hood together. This is really more a lens hood problem than a filter problem. On the few occasions that I was able to place a lens hood over the filters, I twice tried to remove it, forgetting that the filters were still attached, and causing the furthest filter to be accidentally dislodged from the stack. I didn't drop the filter, but it was close.
The do-dad
As you can see in the video, I performed a number of tests with each of these filters. I discovered that the ND1000 neutral density filter does in fact impart a slight color cast. The effect is a very slight warming of the images. Careful assessment of the changes suggests the shift is only about 300 Kelvin towards the warm side. This is neither very significant, nor difficult to correct in any editing program. As long as you are shooting in RAW.
There appeared to be a very trivial color shift with the circular polarizer when fully engaged. This was small enough to be considered a testing error. I was only able to appreciate it by looking at the color temperature readings in Lightroom (it was under 50K).
Perhaps the most consequential finding when using these filters was that I was unable to detect any evidence of internal reflection. This is an extremely important point, given the fact that a lens hood often cannot be used with these filters (as with many other filters). Without a lens hood the risk of internal reflection ruining a photograph is very significant, but I was quite unable to elicit any evidence of internal reflection with any of these filters. There is one other area of concern that I found in using these filters. It is common for filter makers to use aluminum alloys for the filter rings. This is a poor choice of metals but it is understandably the one most often chosen. It is light, cheap, and easy to form. It is also strong and resistant to oxidation. But it does have one major drawback; it binds with the filter threads of many lenses. This may seem like a trivial problem, until you are out in the field far from your vehicle and unable to remove a previously placed filter. It was sufficiently irritating that I began carrying a filter wrench with the filters, everywhere I went.
Now do your impression of Al Pacino!
As I mentioned in the video, these filters are not exactly cheap (they retail for $210 for the large 77mm size). K&F Concept is an organization that I have long admired for its dedication to bringing quality photographic equipment to the masses. They offer low-cost alternatives to the overpriced and over-hyped equipment that saturate the market today. As such, you might be forgiven for thinking that the company sells mostly lower quality merchandise. Indeed, some of the equipment they sell is not what most professionals would choose to purchase, but these filters fall in a different category all together. K&F Concept is clearly stepping up its game, with recent product releases competing with established domestic brands in many categories. The kit of three filters retails in the US for $210. That is about average for most of the good filters currently on the market. There are certainly outliers, some with prices well above that, but that is not the market in which these filters compete. I did not do any direct brand to brand comparison testing, but I do use a great many different brands of filters, and can say with confidence that these perform at or above the level of the majority of them.
If you are in the market for a set of high-quality photographic filters that are optically sound, mechanically solid, and a real pleasure to use, then this is a set that you should consider purchasing. It is well worth the relatively affordable price, especially in light of the generous discounts available through K&F Concept.
The following links are presented for your convenience. The first is to the K&F Concept retail store, where you can purchase this filter set (with a discount). All of the other links are Amazon affiliate links. Please be aware that as an affiliate I may be eligible for a small commission when qualifying purchases are completed using these links.
The filter kit from K&F Concept…
The same filter kit from Amazon…
My favorite lens ever (pre-VR 24-70mm)
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