Between mercury vapor, sodium, Low CRI streetlights, there are many undesirable wavelengths of light that pollute the night sky. The glow from these can keep your camera from seeing the sky properly and ruin your night images. <br><br> Because of this, <b>NiSi </b> has created the <b>Natural Night Filter </b> to block the most common wavelengths of light pollution.<br><br> <b>Like the rest of the NiSi line, this filter is made of high quality, precision annealed, optical glass. Its surface is finely ground and polished to ensure sharpness for today’s ultra high megapixel cameras.The NiSi Natural Night Filter features NiSi’s unique NANO Coating technology. This multi-layer coating reduces reflection on the surface of the filter to help with ghosting and flare. </b> <br><br> It also includes a protective layer that makes it easy to wipe off water, dust, and oil from the filter without worrying about scratching your glass. The NANO Coating process achieves this without loss in sharpness.