Antlia 2.8nm Narrowband SII Ultra Filter

Antlia SII Ultra narrowband filter optimizes the FWHM (full width half maximum) to 2.8nm bandpass. As the bandwidth becomes narrower, the 2.8nm Ultra narrowband filters enhance contrast of emission targets by lowering the unwanted background signal. 

The out of band blocking specification is rated OD5 (0.001%) which delivers an excellent SNR(signal to noise ratio) and effective cut-off rate to minimize interference from other wavelengths.Improved sharp cut-off astrophotography 2.8nm Pro filters are designed to minimize halos around bright stars.

Application and Performance:

High transmittance and smallest bandwidth to maximize contrast

Steep spectral profile minimizes halos around bright stars

A single substrate to eliminate internal reflections

Narrowband Objects: H-alpha Emission Nebulae, Planetary, Wolf Rayet Nebulae and Supernova Remnants

Use in light polluted areas anddark sites

Extends imaging time when the moon is up

All Antlia Narrowband filters are edge blackened to eliminate internal reflections from stray light

Superior optical reliability reduces post image processing

This filter is not suited to deep sky objects that do not contain H-alpha emissions.

Technical Specifications:

Basic Substrate: Schott optical substrate

Filter Thickness: 2mm+/-0.05mm for Dia36mm

FWHM (Full width at half maximum): 2.8nm

CWL (Central Wavelength): 671.6nm

Peak Transmission: ＞88%

Blocking: > 5 OD(0.001% out of band blocking) @ 300-1000nm

Surface Quality: S/D (scratch/dig)= 60/40 (Refer to MIL-O-13830)

Transmitted Wavefront: Lambda/4 or better.

Parallelism: less than 30 arcsec

Single / Non-glued substrate

Warranty: 3-years against delamination