Using Filters on the Camera Lens

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Penllergaer Waterfall, Swansea. B&W. Sutter Speed 1 sec ISO 400. F -16. Lens 18mm. Filter ND4.
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Penllergaer Waterfall, Swansea. Shutter Speed 1 sec. ISO 400. F - 11. Lens 18mm. Filter ND4.
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Stream, Brecon Beacons. Shutter Speed 8 sec. F-stop F29. ISO 100. Lens 18mm. Tripod and ND4 & ND2.