The Antlia OIII 3nm Pro Highspeed 1.25" is a narrowband imaging filter optimized for fast optical systems with focal ratios between f/2.6 and f/3.6. Its pre-shifted central wavelength ensures strong OIII emission contrast and excellent signal-to-noise performance, even under light-polluted skies.

Key features

• optimized for fast f/2.6–f/3.6 optical systems through a pre-shifted central wavelength
• 3 nm FWHM for high contrast in the OIII emission line
• peak transmission of about 90%
• effective compensation of blue-shift effects in fast optical systems
• off-band blocking to at least OD5 (0.001%) from 300–1000 nm
• single-substrate optical construction minimizing halos and internal reflections
• ultra-thin 1.25" filter cell minimizing vignetting
• black anodized housing with laser-engraved markings
• suitable for imaging emission nebulae, planetary nebulae and supernova remnants
• effective under both light-polluted and dark skies, including bright Moon conditions
• not intended for visual observing or for solar observing
• manufacturer warranty: 3 years against coating delamination

Included items

• Antlia OIII 3nm Pro Highspeed 1.25" filter in M28.5×0.6 threaded cell

Technical specifications

• filter type: narrowband, oxygen OIII
• diameter: 1.25" (mounted)
• thread: M28.5×0.6
• full-width at half maximum (FWHM): 3 nm
• central wavelength (CWL): 501.9 nm (pre-shifted for fast systems)
• peak transmission: about 90%
• off-band blocking: ≥ OD5 (300–1000 nm)
• recommended focal ratio: f/2.6–f/3.6
• applications: emission nebulae, planetary nebulae, supernova remnants
• substrate: single optical-grade, non-glued
• surface quality: scratch/dig 60/40 (MIL-O-13830)
• transmitted wavefront: λ/4 or better
• parallelism: <30″ (arcseconds)
• thickness: 2.0 mm ±0.05 mm
• not recommended uses: visual observing, solar observing

Warning: NEVER look at the Sun through the Antlia OIII 3nm Pro Highspeed 1.25" filter. Ignoring this warning can cause permanent eye damage.