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K&F Square 100mm ND1000 filter review

  |   Articles and reviews, Filters, Hardware review, K&F, Photography Ideas, Review   |   8 Comments

100mm square ND1000 neutral density filter

K&F Concept square filter holder and filter

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Square filter holders let you use the same filter for a range of lenses, just changing the thread adapter on the back.

Ones like the K&F one here also let you stack filters (2), although in this instance we’re only looking at the ND1000 filter.

Neutral density filters let you use longer exposures or wider apertures by stopping some light getting into the camera during your shot. The deep 10 stop light reduction of the ND1000 lets you use considerably longer exposures. Typically they are used for blurring movement. Keith has also tried a similar sized reverse graduated ND filter

100mm Square ND1000 filter from K&F Concept

The filter set is also available directly via Amazon
There is an Amazon 10% off code EUFT1495UK valid to the end of March 2019

The 100mm square filter system

The system consists of two parts. First, a mounting frame, which accepts up to two 100mm square filters.


Secondly a set of 7 adapter rings to attach the frame to your lens.


The rings fit the filter thread of your lens.

Sizes supplied are 52mm / 58mm / 62mm / 72mm / 67mm / 77mm / 82mm

Here’s the 82mm on my Canon TS-E24mm MkII tilt shift lens [TS-E24 Lens review]



and EF50mm F1.4


There’s a small brass button that acts as a release clip.


Here’s the frame/adapter attached to the lens.


The filter slots into the frame. A springy plastic guide ensures there’s enough grip to hold it firmly in place.


The filter covers the whole aperture.


One of the advantages of the square filter system is that it lets you use a single set of filters on a range of lenses, such as here on the EF50/1.4

The ND1000 10 stop filter

The filter comes with its own padded case.

100mm nd1000 filter

The case has a magnetic flap, making it unlikely to come open in your bag.

It’s a snug fit, so I prefer to keep the filter glass wrapped in a bit of tissue paper to make it easier to grip when removing it from the case. I used the paper the filter was originally wrapped in.

The ND1000 rating means that about 1/1000 of incident light is getting through the filter

ND1000 is equivalent to 10 stops, meaning that if I needed a 1/1000s exposure for a shot, the filter would lengthen this to 1 second.

That explains typical uses of such filters – long exposures.

ND filter ratings can come in different notations.

ND1xx Notation
ND.xx Notation
NDxx Notation
Fractional Transmittance
Optical density
f-stop reduction
% transmittance
1 1 0.0 0 100%
ND 101
ND 0.3
1/2 0.5 0.3 1 50%
ND 102
ND 0.6
1/4 0.25 0.6 2 25%
ND 103
ND 0.9
1/8 0.125 0.9 3 12.5%
ND 104
ND 1.2
1/16 0.0625 1.2 4 6.25%
ND 105
ND 1.5
1/32 0.03125 1.5 5 3.125%
ND 106
ND 1.8
1/64 0.015625 1.8 6 1.563%
ND 2.0
1/100 0.01 2.0 6 2/3 1%
ND 107
ND 2.1
1/128 0.0078125 2.1 7 0.781%
ND 108
ND 2.4
1/256 0.00390625 2.4 8 0.391%
1/400 0.0025 2.6 8 2/3 0.25%
ND 109
ND 2.7
1/512 0.001953125 2.7 9 0.195%
ND 110
ND 3.0
1/1024 0.0001 3.0 10 0.1%

Note that you need better than ND5000 to photograph the sun with a camera using liveview. Nearer to ND100,000 for safely looking at it.  You also need to be sure that the filter is not letting damaging levels of UV or IR through.

So, if you want to look at the sun, get a specialised solar filter.

Using the square filter system

10 stops lets me reduce my shutter speed to the 1-10 second range, depending on how small an aperture I want to use.

Any colour shift is quite small and easily dealt with through white balance and RAW processing adjustments.

The main use in my work is to blur moving people in my architectural work (see the review of the circular ND1000 filter for more examples).

At 3.2 seconds, most moving people are lost as a faint blur, unless someone is sitting down.
[click to enlarge images]

vjp 3.2 seconds

You’ll notice that at this timescale, people’s feet are often all that shows clearly.

This next shot is at 2.5 seconds and was deliberately taken as the person walked through the beam of sunlight.

Both images taken with a TS-E24mm Mk2 lens shifted upwards.

You do need a bit of luck with such images, so take plenty and see how the patterns of movement look.

Filter build quality

The hard coated filter proved quite resistant to finger marks, and easy to clean. I chose to handle it by the corners where possible, or by the edges.  It’s a snug fit in the soft case, which is well padded.

If you don’t intend stacking filters and only want to use the one lens, the circular version I tested before may be more convenient – it’s much easier to fit in your pocket. although the release clip makes the square filter much easier to fit/remove for composition.

About the filter

This is the second ND1000 filter I’ve looked at. The last one was also from K&F, a normal 82mm ND1000 filter [review]

K&F offer the frame on its own and square filters (currently ND8, ND64, ND1000 and night lighting filters)

The filter is dark enough that you simply can’t see through it when fitted. This means fitting it just when you want to make the exposure, or you may be able to use liveview.

With a DSLR, be careful to cover your viewfinder, since light can leak in to your camera during exposure. Normally this isn’t a problem, but with the much reduced light coming in through the lens when using the filter, it can be an issue.

My main use of filters like this is for my architectural photography where I may wish to blur the movement of people, either to make them less recognisable, or to give a sense of movement and flow.

Buying the filter

K&F 100mm ND1000 filter

The filter set is also available directly via Amazon
There is an Amazon 10% off code EUFT1495UK valid to the end of March 2019

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  • Keith | Aug 19, 2020 at 2:20 pm

    It fits well, but if I had a strong light source hitting the filter from behind I’d definitely want to shield it.
    At ND1000 I’ve never seen this in practice, but if you went darker it would matter a lot more

    For the ND1000 I find the 82mm screw-on one I’ve got easier to use

  • ManixZero | Aug 19, 2020 at 12:37 pm

    Thanks for the review,
    I have a simple question regarding this system.
    How well does the filter fit from a light tightness point of view?
    On issue often found with “cheaper” square filter systems is that the leak light from between the filter and the holder.
    Did you notice any issues, you don’t mention it but I thought worth an ask.


  • Keith | Jun 18, 2020 at 2:33 pm

    Whoops – our comment system dropped my earlier replies.
    As far as I know, K&F don’t actually make a square polariser, so I’ve not tested anything else other than the grad filters they do as well.

  • Ian | Jun 18, 2020 at 1:47 pm

    A helpful and informative article but I have the same question as Andres above. Can you please advise me on what circular polarisers can be attached/slotted in to the K&F filter holder?

  • Keith | Aug 2, 2019 at 1:00 pm

    If you could find one the right size of polariser – K&F don’t do one

  • Keith | Aug 2, 2019 at 12:10 pm

    Yes, there is a very slight loss of contrast with strong lens shift in the periphery. I didn’t notice it with unshifted images but I’d expect a slight loss that would be amenable to different image sharpening.

  • Andres | Aug 2, 2019 at 12:34 pm

    Great article.
    Just a simple question, Are you able to use or attach a circular polarizer filter to this filter holder ?

  • earl.dieta | Aug 2, 2019 at 12:00 pm

    Hi, just wanted to confirm that you did not see any lost IQ with the K&F ND filters?

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