Can cheap ND filters be good? The K&F Concept SN25T1 filter kit says yes

Aug 2, 2020

Paul Monaghan

Creative photographer based in Scotland, Sigma UK Ambassador.

Can cheap ND filters be good? The K&F Concept SN25T1 filter kit says yes

Aug 2, 2020

Paul Monaghan

Creative photographer based in Scotland, Sigma UK Ambassador.

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Over the years neutral density filters have become a staple in my photography. Allowing me more control over my camera exposure.

Good quality filters demand a premium, and while the price has fallen over the years, I often get asked why they cost so much. Particularly for the superior glass filters and filter holders. Well, they don’t have to.

Enter the new K&F Concept SN25T1, a 100mm filter kit with 10stop ND costing just over $70.

General Observations


This 100mm filter kit comes packed with value. It comes with the 100mm holder, several step-up rings, and a 10 stop ND filter. You can see the kit sitting on my Sigma fp and 24-70m f2.8 Art.


While the holder is pretty basic with space for only two 100mm filters and no rear CPL holder.  It is built well and comes with a felt coating to help block stray light from getting behind the filter.

The side of the holder has a small golden release button. Pressing this allows you to remove the holder from the adaptor ring.

I feel this is better than having to pull on pins or leavers that I’ve seen on other filter holders.

This kit comes with a whopping eight adapter rings.  Starting at 49mm all the way to 82mm.

These rings allow the kit to be used on most lenses right away. plus, if you have lenses with different filter sizes then you can leave an adaptor ring on each allowing you to swap the filter holder over easily.


Lastly, the filter is a newly designed 10-stop optical glass ND filter from K&F Concept that comes with a lovely little two-tone case for safe storage.

Inside the case is a little orange tab that runs all the way under the filter and allows for easy removal by pulling the tab up. Sometimes it’s the little things that make me happy.


The most common use I feel for a 10 stop filter would be long exposures.  they make nice smooth water even on fast-moving rivers like the Falls of Dochart at Killin.


Here’s a behind the scene image of me using filters on the Sigma fp with 24-70 f2.8 DG DN Art lens and the K&F SA254T1 tripod.

 

Quality

Considering this entire kit costs less than a decent optical ND filter is the filter itself any good?

For the first test, I grabbed my Sigma sdQ-H with 70-200mm f2.8 at 135mm f8. The reason for this combo is that I’ve had ND filters in the past go soft at longer focal lengths.


I’m happy to say sharpness isn’t an issue at all with it being almost identical to using no filter or the $144 Benro Master 10 stop.  Color shift was -6 Temp and -5 Tint next to the no filter which is pretty minimal and slightly less than the -8 Temp -13 Tint of the Benro.

Next, I wanted to test for Infrared pollution, so I took a shot using a full spectrum sdQ-H (by removing the IR filter) and Kolari Vision IR Chrome filter to show what’s most affect by infrared light.

The difference between having a filter on and using no filter is minimal. (at least after using -6 Temp and -5 Tint correction). This shows that infrared pollution isn’t having a big impact. The K&F holding is ground next to the much more expensive Benro that features an IRND Coating to minimize IR and UV pollution.

Conclusion

For the money, there’s no denying that the K&F filter kit is tremendous value with the 10 stop ND filter delivering optical quality next to filters costing much more. The holder itself is basic but well-built and easy to use.

Anyone looking to start with filters and long exposure should consider this kit for filter alone. (Consider the holder a bonus).  Some holders from other brands do have more advanced features like rear CPL or light shields which is always worth considering before investing tough.

I’ll leave with a few more images taken with the kit and my Sigma fp. I hope you all enjoy:

Glenlyon

Falls of Dochart at Killin

Bonus

I always like to share and help people. I wanted to leave a behind the scenes photo showing how I made the product shots.

Shot using the Sigma sdQ-H with 105 Art

I used some wooden boards, some RGB led lights (Insstro c1) with some paper towel as diffusers at the sides. The main light was a Spiffy Gear Spekular with some tissue diffusing part of it and a little lumiee hiding on top of the boards.

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Paul Monaghan

Paul Monaghan

Creative photographer based in Scotland, Sigma UK Ambassador.

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12 responses to “Can cheap ND filters be good? The K&F Concept SN25T1 filter kit says yes”

  1. Cristiano Diniz da Silva Avatar
    Cristiano Diniz da Silva

    I have one that I bought from Amazon and costed me about 30 bucks and it gives great results. A better filter would bring better results, no doubt in that. Better gear better results.

  2. Lawrie Avatar
    Lawrie

    The link to purchase this unit isn’t working
    Googling your model number doesn’t get any results
    Where can we get one
    Thanks

  3. Mathieu Carbou Avatar
    Mathieu Carbou

    Hi Paul,

    I was intrigued by these filters too but didn’t have a chance to test them.

    I have a mixed feeling when reading the article because we see a lot of articles like this one on Internet comparing filters but it doesn’t really tell if the filter performs as expected. I would have liked to see some more scientific observations regarding the transmission, color neutrality and also if possible for the IR range. I have some questions:

    1. Would you be able to output some more scientific observations regarding the transmission and color neutrality and compare them with some other brands?

    2. What do you mean by “IR” pollution ? There are 2 types of ND filters: normal ND, that are supposed to block IR light and only reduce visible light, and IRND ones, that are supposed to have the same transmission characteristics for both visible and IR light. These filters can consequently be used for IR photography. So what are you really testing here ?

    3. What is the purpose of the IR Chrome filter ? This filter is probably the worst one to use in some comparison because this is a special filter that is mixing some wavelengths from the visible spectrum and IR spectrum. It requires a full spectrum converted camera as such.

    For reference, here is how I am testing the transmission and color neutrality of some Kolari, Formatt and Breakthrough filters (up to 20 stop): https://www.mathieu.photography/Articles/IR-Neutral-Density-Filters

    Thanks :-)

    1. Paul Monaghan Avatar
      Paul Monaghan

      Hi Mathieu.

      When I used the IR chrome filter I removed the internal filter to all the full spectrum of light to enter of my sdQ-H (its user removable)

      The reason I used the IR chrome as it seems to highlight IR sensitive stuff in red making it easier to visualize areas that could be affected more instead of having a full red image.

      Your right this approach might not be the best and I’ll try think of a better way to do this.

      I don’t have any tools to directly measure light waves, but the purpose was to show if IR light was going to have a negative impact on normal long exposurse use which seems to be minimum.

      Sometimes using ND filters can cause say a black t-shirt to change color as the infrared light starts to pollute the image.

      I had a quick look at your testing band it looks very in depth, going to have a proper look once I get settled down.

      Sorry for the late reply, I had an 8 hour drive today for work.

      I hope this helps.

      1. Mathieu Carbou Avatar
        Mathieu Carbou

        Thanks for your fast reply! I understand a bit more what you wanted to test! It is true that depending on the coating, some filters might react differently for the color, transmission and reflection also of IR light. I.e. in my testing I saw that the Firecrest Ultra filters were more susceptible to have some flares when stacked on a deep ir filter.

        1. Paul Monaghan Avatar
          Paul Monaghan

          Interesting, I did like the fire-resistant ultra and the fact the ND coating is on the inside seems to make them more durable.

          Being more complex though they do come at a higher premium and other filters seem to offer slighter better sharpness atleast when I could test with the s1r 147mp.

          In real world use though I feel it would be negligible.

          I’m going to take a better look at your site when I get home, I’m in Orkney just now and want to use my time here wisely.

    2. sir_c Avatar
      sir_c

      On Lenstip dot com they did some nice and thorough test on polarizers a few years back. Would have been nice to have them do the same for ND.

  4. Nermin Huskić Avatar
    Nermin Huskić

    I have some Njy touch, fantastic filters

    1. Paul Monaghan Avatar
      Paul Monaghan

      Nermin Huskić haven’t tried that brand personally but we are lucky in having so many great options these days.

  5. Brianna Jackson Avatar
    Brianna Jackson

    ……………., hi to all photographers. i bough yesterday very cool camera with nice features. i was surprised because have not though that camera for this price can be so perfect for me. i just wanted to share my opinion and maybe some other photographers would like to get it as well, if they do not have budget to buy very expensive ones.hurry up,because it is now in discount 25% in amazon. find the link below:
    https://amzn.to/2Ef4scb

  6. Aris Bottas Avatar
    Aris Bottas

    Dear Paul

    Thank you very much for this excellent review.
    May I ask you whether you have tried the K&F Concept system with Canon lenses like 24-70mm and if you noticed any vignetting issue?
    And a second question : does this system (including the adapter ring) cooperate well with a CPL filter? I guess we screw the CPL filter in the lens and then the adapter ring or the opposite?

    Thanks Paul