Antlia ALP-T narrowband dual filter, 3nm bandwidth, 2" mounted, designed to isolate H-alpha and OIII lines. Perfect for imaging nebulae in light-polluted environments.
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
Hydrogen-alpha | Oxygen III | |
FWHM | 3nm +0.6/-0.1nm | 3nm +0.6/-0.1nm |
CWL (Central Wavelength) | 656.3nm | 500.7nm |
Peak Transmission | 90% | 82% |
Blocking | ≥OD4.5 @ 300-1100nm | |
Filter Thickness | 2mm+/-0.05mm | |
Basic Substrate | Optical, Single / Non-glued substrate | |
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 | 2'' (M48*0.75) | |
Spectrum Curve:
