Optolong 1.25'' L-Ultimate 3nm Dual Band Filter
 Optolong 1.25'' L-Ultimate 3nm Dual Band FilterOptolong 1.25'' L-Ultimate 3nm Dual Band Filter 

Optolong 1.25" L-Ultimate 3nm Dual Band Filter

£299.00✓ 2 year warranty


7x in stock shipped 1-2 working days

About this product

Model:  optolong_l_ultimate

Optolong 12.5" L-Ultimate 3nm Dual Band Filter

The L-Ultimate filter is a 3nm dual narrow band filter designed to drastically reduce the effect of light pollution and hugely increase the quality of your narrowband images.

The 3nm bandpass isolates emission nebulae's emissions into H-Alpha (Red) and OIII (Green and Blue).

This filter effectively blocks light pollution, maximises the signal (OIII 496nm/500nm and Ha 656nm) from your emission nebula target, and darkens the sky background.

The L-Ultimate also effectively blocks artificial light from mercury vapour lamps, high and low-pressure sodium vapour lights and unwanted natural light caused by the emission of neutral oxygen in our atmosphere.

The L-Ultimate is ideal for use with DSLR cameras and dedicated Mono/Colour CMOS and CCD Cameras. 

The advantage of the L - Ultimate is that it only passes the emission lines OIII( 5 0 0 . 7 nm) and Ha( 6 5 6 . 3 nm). Consequently, all other light pollution emission lines are eliminated so that only the emission and reflection signals of the nebula are captured during imaging. Therefore, the sky background of the image is darker, and the contrast between the nebulae and the signal-to-noise ratio is improved to the greatest extent.

The L-Ultimate is different from Optolong's other dual- narrowband Filters ( L- eNhance and L- eXtreme ) in that the L- Ultimate is a dual- 3 nm bandwidth filter that only passes through Ha and OIII emission lines. You will get a darker sky background, more contrast of the image and suppression on stars. L- Ultimate has also been to minimise halos, so there is no obvious halo when shooting a bright star.

This filter is not recommended for use with fast optical systems.



  • 1.25" Mounted
  • Ultra Dual Narrow Band Filter
  • Provides Pinpoint Stars and High Contrast
  • Supplied in a protective plastic case with EVA foam lining
  • More than 150 coating layers on B270 glass.

Transmission Chart



Substrate Optical Glass
Glass Thickness 1.85mm
FWHM 3nm OIII and Ha
Blocking Range 300-1000nm
Blocking >OD4
Surface Quality 60/40
Transmitted Wavefront RMS Lambda/4
Parallelism 30 Seconds


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