Antlia ALP-T Dualband 3nm Ha and OIII Filter - 2" Mounted

Description:
The Antlia ALP-T Dualband 3nm Filter (2" mounted) is a narrow dual-band filter transmitting only the H-alpha (656.3nm) and OIII (500.7nm) emission lines. Designed primarily for one-shot color cameras (OSC), it can also be used as a luminance filter with monochrome sensors to reduce imaging time.

Its ultra-narrow 3nm bandwidth and high optical density (OD4.5) allow efficient blocking of light pollution, moonlight, and skyglow, resulting in high-contrast nebula imaging.

Recommended for optics slower than f/4. For faster systems, a pre-shifted highspeed version is available. Antlia uses double-sided ion-assisted coating on polished substrates for uniformity and precision.

Technical specifications:

• FWHM: 3nm (+0.6 / -0.1nm) for Ha and OIII

• Central wavelengths: 656.3nm (Ha), 500.7nm (OIII)

• Peak transmission: 90% (Ha), 82% (OIII)

• Blocking range: ≥ OD4.5 between 300 and 1100nm

• Thickness: 2mm ± 0.05mm

• Substrate: Optical, single-sided, non-glued

• Surface quality: 60/40 (MIL-O-13830)

• Wavefront flatness: Lambda/4 or better

• Parallelism: < 30 arcsec

• Thread: 2" (M48x0.75)

Additional information:

• Designed for OSC but also works with mono sensors

• AR coating to suppress halos and internal reflections

• Ultra-thin cell to reduce vignetting

• Permanent laser engraving

• Recommended with Antlia SII&Hb filter to create 4-channel narrowband images (Ha, OIII, SII, Hb)

• Not for solar imaging or nighttime visual use

• Do not observe the Sun with this filter

Technical Specifications

Spectrum Curve: