Antlia 3nm Pro OIII filter

Antlia OIII (Oxygen III) 3nm Pro filter

Interferential Filter for Astrophotography

The Antlia OIII Pro narrow-band filter optimizes the width at half-maximum (FWHM) to 3nm. This narrow width enhances the contrast of emitting targets by reducing spurious background signal. It is designed to offer 88% transmission at 500.7nm wavelength, guaranteeing maximum signal and excellent definition of nebulous structures.

Wider narrowband filters generally result in a significant loss of transmission due to center wavelength shifts (CWL). The 3nm Pro filter guarantees >88% transmission in a ±1nm range around the center band, enabling compatibility with high-speed optics up to f/3 without significant signal loss.

Out-of-band rejection is rated at OD5 (0.001%), offering an excellent signal-to-noise ratio and effective cutting of spurious wavelengths. This filter is designed to minimize halos around bright stars, thanks to its sharp spectral profile.

Application and performance

• High transmission and narrow bandwidth for maximum contrast
• Steep spectral profile to limit halos
• One-piece substrate to avoid internal reflections
• Target objects: OIII nebulae, planetary nebulae, Wolf-Rayet, supernova remnants
• Suitable for polluted skies or dark sites
• Extends imaging time even with the Moon
• Compatible up to f/3 without significant signal loss
• Blackened edges for unmounted filters to avoid internal reflections
• Optical reliability reduces post-processing retouching
• Specially designed for deep-sky objects containing OIII emissions

Technical specifications

Spectral curve

Mounting ring

• 1.25'' (M28.5×0.6), 2'' (M48x0.75)
• Ultra-fine cell for reduced vignetting
• Black anodized finish, unalterable laser engraving

Major nebula emission lines

• H-α : 656.3nm
• H-β : 486.1nm
• OIII: 495.9nm and 500.7nm

Available sizes

• Mounted: 1.25″, 2″
• Unmounted: Ø31mm, Ø36mm, Ø50mm, square 50x50mm

Not recommended for :

• Solar observation
• Visual observation at night

Warning:

NEVER LOOK AT THE SUN WITH THIS FILTER. Serious eye damage may occur.