Antlia 4.5nmnm H-alpha (Ha) EDGE Filter
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Antlia 4.5nmnm H-alpha (Ha) EDGE Filter

£201.00✓ 2 year warranty


1x in stock shipped 1-2 working days

About this product

Model:  antlia_ha_4_5nm_31mm

Antlia 4.5nmnm H-alpha (Ha) EDGE Filter

Antlia H-alpha EDGE narrowband filter optimise the FWHM (full width half maximum) to 4.5nm bandpass. The suppression of optical density (OD) 5 on unwanted wavelengths and the excellent transmittance characteristics found in the Antlia 3nm Pro series has been incorporated into the 4.5nm EDGE narrowband filters. The result is that these filters deliver superior SNR (signal to noise ratio) and better contrast in your images.

Antlia H-alpha 4.5nm EGDE filters are designed to deliver high transmittance at the 656.3nm line that provides you with the maximum signal to reveal the faintest H-alpha nebulae structures.

Conventional broader narrowband filters cause a heavy loss in transmission due to the strong Centre Wavelength (CWL)-shift. We guarantee T>90% within 1nm range of the centre bandwidth, which means that the H-alpha 4.5nm EDGE narrowband filters can guarantee high transmittance for working with both long focal ratios and fast optical systems. Blue-shift data shows that Antlia 4.5nm EDGE filters can be used with nearly all systems as fast as f/3 with minimal loss in emission signal and meets the requirements of fast optics.

IMPORTANT: These filters are NOT designed for observing or photographing the Sun. DO NOT use these filters to observe or photograph the Sun. If you do it will result in permanent eye damage! 


  • 4.5nm FWHM Ha filter - 656.3nm centre wavelength
  • High transmittance and narrow bandwidth to maximise contrast
  • Steep spectral profile minimises halos around bright stars
  • A single substrate to eliminate internal reflections
  • Narrowband Objects: H-alpha Emission Nebulae, Planetary, Wolf Rayet Nebulae and Supernova Remnants
  • Use in light polluted areas and dark sites
  • Extends imaging time when the moon is up
  • Antlia narrowband EDGE filters can be used down to f/3 systems with minimal loss of signal
  • Edge blackened to eliminate internal reflections from stray light
  • Superior optical reliability reduces post image processing
  • This filter is only effective for deep sky objects that contain H-alpha emissions
  • 2mm+/-0.05mm thickness for 1.25", 2" mounted, 31mm and 36mm unmounted
  • 3mm+/-0.05mm thickness for 50mm and 50x50mm unmounted
  • Fine-optically polished on both sides 

Transmission Chart

Purple Line - Represents the transmission curve of the filter.

The Major Emission Lines of Nebulae: H-α (656.3nm), H-β (486.1nm), OIII (495.9nm) and OIII (500.7nm)

The Major Emission Lines of Artificial Light Pollution: Hg / Mercury (435.8nm, 546.1nm, 577nm and 578.1nm), Na / Sodium (598nm, 589.6nm, 615.4nm and 616.1nm)



Basic Substrate: Optical, Single / Non-glued substrate

Filter Thickness:   

2mm+/-0.05mm for 1.25", 2" mounted, 31mm and 36mm unmounted
3mm+/-0.05mm for 50mm and 50x50mm unmounted

FWHM (Full width at half maximum): 4.5nm

CWL (Central Wavelength): 656.3nm

Peak Transmission:>90% Blocking: > 5 OD (out of band blocking) @ 300-1000nm

Surface Quality: S/D (scratch/dig)= 60/40 (Refer to MIL-O-13830)

Transmitted Wavefront: Lambda/4 or better. Parallelism: less than 30 arcsec

Filter Ring:

1.25’’(M28.5*0.6) or 2’’(M48*0.75)

Ultra-thin filter cell to minimise vignetting

Black anodised finish Laser engraving

No fading

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