OPTOLONG L-Extreme Filter NK-Z Compatible with Nikon Full Frame Micro-Single Camera Built-in Filter Z Series: Z5 Z6 Z6II Z7 Z7II Z8 Z9 ZF

• The L-eXtreme filter is dual band that passes Ha and OIII emission lines.The advantage of the L-eXtreme filter is that there is no transmission between the H-beta and OIII lines, as there is no nebula emission lines there. In this case, it isn't letting light pollution come through so that maximize nebulas signal and make the sky background darker while imaging. The L-eXtreme filter should better isolate the emission lines only and better protect from light pollution.
• Hydrogen is the largest, the most primitive, the simplest, and the oldest element in the universe. Scientists consider that Hydrogen amounts to more than 90% of visible substance in space. Our sun is 5 billion years old, but so far hydrogen is still the key matter of nuclear fusion. While the sulfur element does not have much scientific significance, so keeping H and O is meaning for exploration of life. Therefore, we highlight H-a, H-b, O3 and O2, and reduce the signal of sulfur.