The Antlia SII 3nm Pro filter is designed to provide 88% transmission in the 671.6nm line, giving you maximum signal and well-defined nebula structures.
Conventional wider narrowband filters cause high transmission loss due to the strong center wavelength shift (CWL). We guarantee T>88% within the 1nm range of the central bandwidth, which means that the 3nm Pro narrowband filter can guarantee high transmittance to work with both long focal ratios and fast optical systems. The blueshift data shows that Antlia 3nm Pro filters can be used with almost all systems as fast as f/3 with minimal loss of the emission signal and meets the requirements of fast optics such as Hyperstar and RASA.
The out-of-band blocking specification is OD5 (0.001%), providing excellent SNR (signal-to-noise ratio) and an effective cut-off rate to minimize interference from other wavelengths. Pro 3 nm astrophotography filters with enhanced sharp cut-off are designed to minimize halos around bright stars.
Application and performance
High transmittance and minimum bandwidth to maximize contrast
Steep spectral profile minimizes halos around bright stars
Single substrate to eliminate internal reflections
Narrow band objects: SII emission nebulae, planetary nebulae, Wolf-Rayet nebulae and supernova remnants
Use in light-contaminated areas and dark locations
Extend imaging time when moon is present
All Antlia Pro narrow-band filters can be used down to F/3 with slight signal loss
All Antlia narrow band filters have blackened edges to eliminate internal stray light reflections
Superior optical reliability reduces image post-processing
This filter is not suitable for deep sky objects that do not contain SII emissions.
Technical Specifications
Basic substrate: Schott Optical Substrate
Filter thickness： 3mm+/-0.05mm
FWHM (Full width at half maximum) 3nm
CWL (Center Wavelength): 671.6nm
Maximum transmission: ＞88%.
Blocking: > 5 OD(0.001% out-of-band blocking) @ 300-1000nm
Surface Quality: S/D (scratching/excavation)= 60/40 (see MIL-O-13830)
Transmitted wavefront: Lambda/4 or better.
Parallelism: less than 30 arcsec
Single substrate / not bonded
Warranty: 3 years against delamination
Not recommended
Solar observation and imaging
Visual observation
DO NOT LOOK AT THE SUN WITH FILTERS ANTLIA.
Failure to heed this warning can result in serious eye injury.
When designing filters for astronomical imaging systems, we take into account how they will work together with the optical systems, carefully designing the blocking and bandpass parameters for optimum performance. The out-of-band blocking ratio is a very important performance index, as it is designed to sharply attenuate out-of-band wavelengths. The result is that the Antlia SII 3nm Pro filter offers excellent contrast with extremely dark backgrounds, while providing high transmission of the SII signal. These types of filters are more difficult to produce at a consistently high level of quality.
Each filter is individually tested and scanned to ensure that the quality meets high performance parameters. The end result is a filter that achieves excellent contrast, but at a higher production cost. We believe the price-performance ratio is more favorable than similar premium filters on the market.
