Antlia ALP-T Dual Band 5 nm H-alpha & OIII — 2" mounted (standard) The Antlia ALP-T Dual Band 5 nm is a dual line-pass filter, designed mainly for one-shot-colour cameras such as DSLRs and colour astronomy cameras. It isolates the red H-alpha and blue-green OIII lines of emission nebulae with OD4.5 suppression of light pollution, moonlight and airglow.…
Manufacturer model: Antlia ALP-T Dual Band 5nm Ha&OIII, 2-inch mounted (standard) · Specifications checked against manufacturer data on 2026-11-03
The Antlia ALP-T Dual Band 5 nm is a dual line-pass filter, designed mainly for one-shot-colour cameras such as DSLRs and colour astronomy cameras. It isolates the red H-alpha and blue-green OIII lines of emission nebulae with OD4.5 suppression of light pollution, moonlight and airglow. It can also be used as a narrowband filter with mono cameras to save imaging time.
Coating and construction
Ion-gun-assisted deposition coatings on a double-side-polished substrate give extremely steep band edges and a flat-topped passband. Antlia designs it to work from Bortle 1 to Bortle 8 skies, and it blocks near infrared to 1100 nm. The filter sits in an ultra-thin cell that maximises clear aperture and minimises vignetting.
Standard or Highspeed
This is the standard version, which Antlia recommends for optics slower than f/3.6. For f/2.2 to f/3.6 systems, Antlia makes a separate Highspeed version with slightly shifted passbands.
Not for solar use. Do not look at the Sun with this filter.
Specifications
H-alpha band
CWL 656.3 nm; FWHM 5 nm; peak transmission 92%
OIII band
CWL 500.7 nm; FWHM 5 nm; peak transmission 88%
Blocking
OD4.5 or better, 300–1100 nm
Thickness
2 mm ±0.05 mm
Recommended focal ratio
Slower than f/3.6 (standard version)
Cell
2-inch, M48 × 0.75; ultra-thin, black anodised, laser engraved
Standard version assumed (title has no 'Highspeed'). Highspeed version: CWL 657.8/502.2 nm, 88/82%, OD4.5 300–1050 nm, for f/2.2–f/3.6. Not the SII&H-beta ALP-T.
Antlia ALP-T Dual Band 5 nm H-alpha & OIII — 2" mounted (standard) The Antlia ALP-T Dual Band 5 nm is a dual line-pass filter, designed mainly for one-shot-colour cameras such as DSLRs and colour astronomy cameras. It isolates the red H-alpha and blue-green OIII lines of emission nebulae with OD4.5 suppression of light pollution, moonlight and airglow.…
Manufacturer model: Antlia ALP-T Dual Band 5nm Ha&OIII, 2-inch mounted (standard) · Specifications checked against manufacturer data on 2026-11-03
