Optolong L-eNhance is a dual-band pass filter which has been designed for DSLR (digital SLR), color CMOS and monochrome CCD cameras. The convenience and cost effectiveness of this filter allows amateurs to image a rich selection of astronomical images, even in bright, heavily light-polluted areas. It effectively isolates the H-Alpha, H-Beta, and Oxygen III nebula emission lines and achieves a maximum transmission of up to 90%. The performance of this filter delivers images that superbly control.
 
L-eNhance Introduction
The relentless spread or urbanization and its associated light pollution have become a growing problem for all amateur astro photographers. The current solutions to the problem can be expensive and might include the purchase of a monochrome camera, several types of narrowband filters and a filter wheel.
Optolong L-eNhance provides an economical and practical solution for amateurs. It is a dual-band pass filter which has been designed for DSLR (digital SLR), color CMOS and monochrome CCD cameras. The convenience and cost effectiveness of this filter allows amateurs to image a rich selection of astronomical images, even in bright, heavily light-polluted areas. Optolong believes the design of our L-eNhance filter is a technical innovation among filters. It effectively isolates the H-Alpha, H-Beta, and Oxygen III nebula emission lines and achieves a maximum transmission of up to 90%. The performance of this filter delivers images that superbly control the impact from light polluted skies.
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.
 
Spectrum and Characteristic
Sbustrate: B270
Thickness: 1.85mm
Tpeak:  T>90%
Blocking range: 300-1000nm
Blcoking depth: light pollution  line blocking >99%
Surface quality: 60/40
Transmitted Wavefront RMS: λ/4
Parallelism: 30s
 
Specifications
Optolong L-eNhance features:
★1.25"(1 1/4" mounted), 2" mounted for eyepiece
★SLR Camera clip filters: EOS-C
 
Coating Technology
Multi-layers anti-reflection coating
Non-cementing optical substrate coating
Optolong L-Pro filter adopts precision coating based on Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL(central wavelength) no deviation affected by temperature change.
Planetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and Optical density of off-band.
How to read the chart?
The horizontal axis is the Wavelength in Nanometers(nm).
The vertical axis is transmission in %.
The WHITE line shows the transmission of the filter. THe artificial lines are shown in YELLOW. H-Beta line is shown in BLUE, OIII line  is shown in GREEN, and H-Alpha line is shown in RED.
COATING TECHNOLOGY
Multi-layers anti-reflection coating
Non-cementing optical substrate coating
Optolong L-Pro filter adopts precision coating based on Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL(central wavelength) no deviation affected by temperature change.
Planetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and Optical density of off-band.