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.

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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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