【2020 NEW】L-eXtreme Dual-band Filter
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.
  • Description

  • Specification

1.  L-eXtreme Introduction

Optolong L-eXtreme is a two 7nm 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 nebulas, even in bright, light pollution skies. Optolong believes the design of L-eXtreme filter would be better choice for fast systems in 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 is living in very light polluted areas, or when the moon is out, the L-eXtreme will be a good filter.

 

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.

Unlike the L-eNhance filter which is a tri-band (transmits Hb, Ha, and OIII), the L-eXtreme filter is dual band that passes Ha and OIII emission lines.



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.

 

2.Spectrum and Characteristic
 

Sbustrate: B270
Thickness: 1.85mm
FWHM:  O3 7nm+Ha 7nm
Blocking range: 300-1000nm
Blcoking depth: light pollution  line blocking >99%
Surface quality: 60/40
Transmitted Wavefront RMS: λ/4
 Parallelism: 30s

 

 

How to read the chart?

▲The horizontal axis is the Wavelength in Nanometers(nm).

▲The vertical axis is transmission in %.

▲The RED line shows the transmission of the filter. The artifical emission lines are shown in ORANGE. And the emission lines from constellation are shown in GREEN.

 

 

3. L-eXtreme Gloable MAP

 

      Item's Name           Specification           Detail Price in $US     
L-eXtreme 1.25" $239.0
L-eXtreme 2" $309.0

 

 

4. Manufacturing Technology

  • High-precision grinding and polishing to make sure the substrate parallelism is greater than 30" and the surface accuracy is better than λ/4 ;
  • Purified water ultrosonic clearning is aim to effectively remove impurities and dust from the substrate surface.
  • Electron-beam gun evaporation with 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; IAD not only consolidates membrane compactness, increases film firmness, but also changes vacuum coating material characteristics.
  • Planetary rotation system offers precision and homegeneity of coating ensuring high value on transmission of pass-band and Optical density of off-band;
  • Non-cementing optical substrate coating;
  • Quality Control: each filters is examined by Spectrophotometer for spectrum characteristic, and Laser Interferometer for surface accuracy.

 

 

5. Packing

Outer Box: silve box

Plastic Box: PP material

Lining: imported high pressure white EVA material

2020 NEW PACKAGING

※NOTE:

New and old packaging replacement period, random delivery. Many thanks for your understanding.

 

6. L-eXtreme Filter Performance

 

I. Compare: L-eXtreme VS no filter © Vincent Cheng

Object: M42 Time : 15th.--16th. March 2020 Place: HongKong-Shatin

Camera : ZWO ASI183MC Pro Telescope : f/5 @ Sky-Watcher N130/650 w coma corrector

Filter : Optolong  L-eXtreme 2"

Mount : iOptron CEM25EC

Guide : 120mm mini guide scope, ZWO ASI120MM mini

Light pollution level 7~8(City center, light pollution disaster area)

Copyright: ©Vincent Cheng (Hong Kong)

 

 

II. IC1396 "Elephant Trunk Nebula" to Sh2-129 "Flying Bat", imaged by José Jiménez

The Optolong L-eXtreme, a dual band of H-Alpha and OIII in 7nn, two in one !! Increasingly, light pollution is the main problem for those of us who dedicate ourselves to astrophotography and this filter is a great solution, since it effectively isolates and enhances the emission lines of the H-Alpha and OIII nebulae, I definitely recommend it to reduce light pollution, increase the contrast of emission nebulae and save time in the process combining narrow band shots with RGB shots, ideal for those who use DSLR and CMOS color cameras !!

La Jonquera - Girona - Spain - April 2020

Equipment used :

Canon 6D mod & WO SpaceCat 51

RGB 25 x 600" ISO 3200 - Optolong L-Pro
H-Alpha & OIII 20 x900" ISO 3200 - Optolong L-eXtreme

Sky Watcher EQ6 Mount
Guide camera QHY5
Flats, Darks & Bias

 

 

 

III.  M8, imaged by Vincent Cheng (HongKong)

Date : 30 APR, 1 MAY 2020
Location : Lower Shing Mun Reservoir, Shatin, Hong Kong
Camera : ZWO ASI183MC Pro (cooled at -10C)
Telescope/Lens : SVBONY SV48 (500mm f5.5)
Filter : Optolong L-eXtreme 2" Prototype
Tracking Mount : Sky-Watcher AZ-GTi
Autoguide : 120mm mini guide scope, ZWO ASI120MM mini
Controlled through ASIAIR PRO and SkySafari 6 plus

Total Exposure Time : 5mins X 21frames
w Dark Frames
process w PI, PS CC
Bortle scale: level 7~8

 

 

Optolong L-eXtreme features 1 sizes:

★1.25"(1 1/4" mounted),  2" mounted for eyepiece