Review: K&F Concept ND Filters

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Recently, I was contacted by K&F Concept to review two of their products — one is a variable ND filter and the other is a kit of three, different strength, ND filters. K&F Concept is not paying me for this review but they did send me the filters for free. Also, I am not an affiliate for them so I won’t make any commission if you purchase the product mentioned. Please read my Code of Ethics Statement HERE

K&F Concept is a Chinese company offering bargain prices on photography gear and as many of you know, in the past, I’ve reviewed a camera backpack and a tripod from them and found those items to be, for their price, excellent. When they asked me to review their ND filters, I was excited to try them out — typically, to get a good ND filter means to part with significant dollars. The products they wanted me to review were very reasonably priced — so much so, I was a bit skeptical as to whether they’d be any good. You’ll see, my skepticism was warranted.

For those of you that aren’t familiar with ND filters, ND stands for Neutral Density. Theoretically, a neutral density filter will restrict the amount of light entering the camera but not shift the color. Photographers like to use neutral density filters on brighter days to achieve slower shutter speeds or wider apertures. For example, a landscape photographer my want to blur the flow of water over a waterfall by using a slower shutter speed. If it’s bright out, they often won’t be able to achieve a shutter speed slow enough to get the blurred water they desire. An ND filter solves that problem

Another example is a portrait photographer shooting in existing light. The photographer may want to use a wide open aperture to blur the background behind their subject but, if it’s too bright, they may not be able to open up their lens enough to achieve the bokeh they desire. An ND filter will restrict the light hitting the sensor allowing them to use the wider aperture they require.

As I mentioned, they sent me two different products — the first we’ll talk about is their ND Filter Set consisting of three different ND Filters — ND2, ND4, and ND8 representing the light reduction as follows:

  • ND-2 >> -1-stop
  • ND-4 >> -2-stops
  • ND-8 >> -3-stops

The pouch is nice but the filters seem to be cheaply made. Feather light and plasticy feeling — a single one of these filters weighs 0.4oz whereas the equivalent filter from Tiffen weighs 1.3 oz’s. So, the Tiffen filter weighs more than three times as much as the K&F Concept Filter.

The kit came with a nice carrying pouch and a small, multifiber cloth.

Weight isn’t the deciding factor – performance is. When you use them, how do the pictures look?

To find out, I took my Nikon D850, Nikon 24-70mm F2.8 Lens and my tripod down to the shore of Lake Erie. I felt the waves would make obvious the effect a slower shutter speed might imbue upon the scene.

I setup my tripod and put my camera in aperture priority mode — F8.0 with an ISO of 64. As reference, I took the following shot without any filter on the camera:

1/160 sec, F8.0 iso: 64 at 29mm

All images were processed minimally in Lightroom.

I then put on the ND-2 Filter and took the following picture:

1/80 sec, F8.0 iso: 64 at 29mm

Two issues I’ve encountered with ND filters are 1.) they often aren’t accurate, meaning if they say they’re 1-stop, they’re actually, 0.80-stop — as you can see, this filter seems accurate — 1/80th of a second is exactly 1-stop less than the image shot without any filter — 1/160th of a second. 2.) They often will shift the color and all too often, the color shift is difficult to remove in post. Neither of these images were color corrected and depending on your monitor, you may be able to see a slight color shift. Definitely nothing major and something that should be easily corrected in post.

Next, I put on the ND-4 filter — 2-stops of light reduction:

1/40 sec, F8.0 iso: 64 at 29mm

Again, it’s perfect as far as the light reduction – 2-stops is 1/40th of a second — also, the color shift isn’t severe at all.

Finally, I put on the third filter of the set, the ND-8 – 3-stops of light reduction:

1/20 sec, F8.0 iso: 64 at 29mm

Awesome! It turned out to be exactly 3-stops of light reduction and the very slight color shift can easily be corrected.

So, individually, they work fine but as you can see, 1, 2, and 3 stops of light reduction are not very significant. Usually, we’ll require more and the nice thing about these types of ND filter sets is that you can stack them. Their light stopping characteristics are additive when stacked so if we stack all three of these filters, we’ll end up with a 6-stop ND filter. Here is that result:

0.6 sec, F8.0 iso: 64 at 29mm (Not color corrected)

6-stops of light reduction should have produced a shutter speed of 0.4 sec but, as you can see, this image came through at 0.6 sec. This is more likely because the light in the scene got a bit darker between shots. The main issue is the severe color shift. As you can see, this image is significantly cooler than the others. I was able to correct it in post… kind of — I really don’t like the color though and it would require more white balance work to be acceptable:

0.6 sec, F8.0 iso: 64 at 29mm (Color corrected)

You’ll notice that I shot all of these images at 29mm. When you stack these filters, like any stack, of any filter, you must be cognisant of vignetting of the image when you shoot wide. 29mm was the widest I could go without getting any lens vignetting. Below is an image shot with the three filter stack at 24mm — the widest this lens can go:

3-filter stack shot at 24mm

Overall, these filters performed a bit better than I expected but, they’re not something I would use. I think they’re too cheaply made and like most filters, if you screw them on a bit too tight, you’ll get them stuck and unlike better filters made of heavier material, I believe you’ll destroy these getting them unstuck.

The other reason I won’t use these is, as mentioned, 1, 2, and 3 stops of light reduction is not very significant and once you start stacking the filters, you’ll start to see a large color shift. Most, higher end, ND kits contain filters that have reductions of 2, 3, and 4 stops allowing, when stacked, a reduction of 9-stops without minimal color shift.

The price is attractive — ranging, on Amazon, between $12 and $18 for the entire set depending on what size you purchase. Still, I cannot give these my endorsement hence, I will not supply my Amazon Affiliate link for the product.


Next, I tried out the K&F Concept Variable ND Filter

This filter seemed to be significantly better made then the kit filters. It is of rather robust build and weighs 1.8 oz’s. It comes with a microfiber cloth and a plastic case.

This variable ND filter is supposed to range from ND-2 (1-stop) to ND400 (~9-stops – actually, 8.65 stops but it is often rounded up when referenced).

All variable ND Filters consist of two pieces of polarized glass – one fixed and one that spins in relation to the other. The more you spin it, the less light gets through.

The main issue photographers encounter when using variable ND filters is they turn them past the point suggested on the filter. After all, the more you turn it, the darker it gets and most often, we want to get a very slow shutter speed or, use a super wide aperture so we’d like to get the filter as dark as possible. When a variable ND Filter is turned too far, too dark, you’ll encounter a weird cross banding that ruins the picture — there is no way to get rid of it in post.

As far as this filter is concerned, when you look at the side of it, and as you can see in the picture of the filter below, there is a “max” setting. Shooting the same scene, I set this filter to that MAX setting. AS a matter of fact, I set the filter so it was directly set to the “A” in MAX:

 

This is the result:

That is the weird banding I’m talking about. So, you cannot set it to MAX. Maybe they meant that dot that is located directly before MAX. The lens won’t be as dark but let’s try it:

0.8 sec, F8.0 iso: 64 at 29mm (Not color corrected)

The color shift isn’t too significant but, that banding is there — lightly but there none-the-less and it’s impossible to remove in post production. Also, it came through with a shutter speed of 0.8 sec. which equates to between 7 and 8 stops of light reduction. So, it didn’t come close to ND400 (~9-stops) without banding.

$26 for a variable ND filter did seem too good to be true and unfortunately, I cannot endorse this product either.

It appears that to get expected results from an ND Filter, you’ll have to pony up the bucks for a quality product.


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