Antlia SII 3nm Pro narrowband filter optimizes the FWHM (full-width half maximum) to 3nm bandpass. As the bandwidth becomes narrower, the 3nm Pro narrowband filters enhance the contrast of emission targets by lowering the unwanted background signal. Antlia SII 3nm Pro filter is designed to deliver 88% transmission at the 671.6nm line which provides you with the maximum signal and well-defined nebulae structures.
Conventional broader narrowband filters cause a heavy loss in transmission due to the strong (Center Wavelength (CWL)-shift. We guarantee T>88% within 1nm range of the center bandwidth, which means that the 3nm Pro narrowband filter can guarantee high transmittance for working with both long focal ratios and fast optical systems. Blue-shift data show that Antlia SII 3nm Pro filters can be used with nearly all systems as fast as f/3 with minimal loss in emission signal and meet the requirements of fast optics like Hyperstar and RASA.
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 3nm Pro filters are designed to minimize halos around bright stars.
Application and Performance:
High transmittance and smallest bandwidth to maximize contrast
A steep spectral profile minimizes halos around bright stars
A single substrate to eliminate internal reflections
Narrowband Objects: SII Emission Nebulae, Planetary, Wolf-Rayet Nebulae and Supernova Remnants
Use in light-polluted areas and dark sites
Extend imaging time when the moon is up
All Antlia narrowband Pro filters can be used down to F/3 with a slight loss of signal
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 SII emissions.
Basic Substrate: Schott optical substrate
Filter Thickness：2mm+/-0.05mm for 2” mounted
FWHM (Full width at half maximum): 3nm
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