K&F Concept 100mm ND8 3 Stop Neutral Density Square Filter

I’ve just taken delivery of the K&F Concept 100mm ND8 3 Stop Neutral Density Square Filter to add to my growing collection of K&F filters.  As expected, the ND8 arrived in the usual high quality packaging, well protected for transit in it’s sturdy faux leather case with magnetic catch.

So what is an ND8 filter? Neutral density filters are available in different strengths/darkness which reduces by a specific number of stops of light.  The filters are labelled in two ways (neither of which is the number of stops!) by Optical Density or by ND Factor.  Here’s a simple table that shows the main filters.

Stops of Light ND Factor Optical Density
1 2 0.3
2 4 0.6
3 8 0.9
4 16 1.2
5 32 1.5
6 64 1.8
7 128 2.1
8 256 2.4
9 512 2.7
10 1024 (aka ND1000) 3

So, an ND8 filter reduces by just 3 stops of light.  As an example, under average day time conditions where we might be getting a correct exposure of 1/125s the ND8 would allow us to drag the shutter out to 1/15s.

Here is a useful grid to calculate the expected long exposure for different ND filters.

So the K&F Concept ND8 filter, based on the extra 3 stops, I decided would be best used to help me capture some minimalist wave photography on a recent visit to Seaham beach on the North East coast of England.

I was shooting on a fairly overcast morning and the correct exposure was 1/4s at f/11 on my Sigma 10-20mm, adding the ND8 pushed the exposure to 2 seconds.  1-2 seconds is a perfect length to capture the gentle motion of the waves lapping on the beach.

As with the other K&F Concept Pro ND filters, the coating is absolutely colour neutral and adds no colour cast to the final images.

Here is a selection of the final images taken on the day.

The K&F Concept ND8 100mm Pro Filter is available from the Kent Faith website and also from Amazon.  If you purchase by 30/12/2019 you can also get 10% OFF using the discount code: KF10UK

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