Optolong L-eXtreme F2 Dual Band 2 Inch Nebula Filter


  • €349,95
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Optolong L-eXtreme F2 Dual Band 2 Inch Nebula Filter


Optolong L-eXtreme F2 is a dual-band (500.7 nm and 656.28 nm, FWHM=7 nm) narrowband pass filter that meets the requirements for transmission at continuously varying angles. Astronomically characterised spectral lines (OIII, Ha) as the main transmission wavelengths, the OIII and H-Alpha nebula emission lines pass accurately at f2 - f3.3 Focal Ratio.


Together with one-shot colour astronomical cameras, monochrome astronomical cameras, and Digital SLR cameras, you can fast and quickly obtain clear and detailed images of the deep sky;

Ideal for fast optical system, like RASA, Hyperstar and other fast focal ratio telescope users;

Recommended for using fast optical system with focal ratio from f2 to f3.3;

Anti-light pollution、better contrast、more details of the celestial bodies:This filter cuts out background light and noise beyond the target celestial bodies to get better details and contrast of the images. L-eXtreme F2 can effectively block light pollution so that the images will not affected by unwanted lights, and sky light of the background. You can quickly get satisfactory pictures in fast optical systems.

L-eXtreme F2 Coating Technology

Multi-layers anti-reflection coating

Non-cementing optical substrate coating

Optolong 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.

L-eXtreme Specification

Substrate: Optical Glass
Thickness: 1.85mm
Blocking range: 300-1000nm
Blocking depth: >OD4
Surface quality: 60/40
Transmitted Wavefront RMS: λ/4
Parallelism: 30s


WARNING: The filters of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.


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