The advantage of the L-eXtreme filter is that there is no transmission between the H-beta and O-iii lines and there are also no nebula emission lines there. In this case, it isn't letting light pollution come through so it maximizes nebula signals and the sky background is made darker while imaging.
The L-eXtreme filter should better isolate the emission lines and better protect from light pollution.
Optolong L-eXtreme is a two 7 nm bandpass filter which can be used with one-shot color cameras like DSLR's (digital SLR), and monochrome CCD cameras, it is also more suited for fast systems. The convenience and cost-effectiveness of this filter allows amateurs to image a rich emission nebula, even in bright, light pollution skies. Optolong believes the design of L-eXtreme filter would be a better choice for fast systems at a competitive price. It isolates the H-Alpha, and Oxygen III nebula emission lines so that the contrast and signal-to-noise ratio between nebulae were maximized. For people who are living in very light-polluted areas, or when the moon is out, the L-eXtreme will be a good filter.
Unlike the L-eNhance filter which is a tri-band (transmits H-b, H-a, and O-iii), the L-eXtreme filter is dual-band that passes H-a and O-iii emission lines.
Comparison of transmission lines of L-eXtreme, L-eNhance, and L-Pro:
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 for the exploration of life.
Therefore, we highlight H-a, H-b, O-iii, and O-ii, and reduce the signal of sulfur.
Spectrum and Characteristic
Thickness: 1.85 mm.
FWHM: O37 nm+Ha 7 nm.
Blocking range: 300 to 1000 nm.
Blocking depth: light pollution line blocking >99%.