Antlia PRO Ha, SII, OIII Ultra Narrowband filter set, 3 nm (36 mm, unmounted)

The Antlia Pro narrowband filter optimizes the FWHM (full width half maximum) to 3nm bandpass. As the bandwidth becomes narrower, the 3nm Pro narrowband filters enhance contrast of emission targets by lowering the unwanted background signal. Antlia 3nm Pro filters are designed to deliver 88% or higher for Ha and SII, and 85% or higher for OIII 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 shows that Antlia 3nm Pro filters can be used with nearly all systems as fast as f/3 with minimal loss in emission signal and meets 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:

• Ultra-narrow 3.0 nm bandwidths, designed for astronomy imaging in both light polluted areas and at dark sites；
• Suitable for imaging of H-Alpha emission in nebulae, planetary nebulae and supernova remnants;
• With the Ha, SII, OIII set of filters you are able to process your images to achieve the impressive Hubble color palette;
• With the Ha and OIII filters these can be used to achieve great narrowband results using the Bi-Color process;
• High transmission of typically 90% and sharp cut-off delivers an excellent boost in contrast for emitting objects;
• All Antlia Narrowband filters are edge blackened to minimize interference from stray light;
• This filter is not suited to deep sky objects that do not contain Ha emissions. It can be used to image Ha regions in galaxies and such images can be combined into LRGB images to better highlight the Ha emitting regions of galaxies.
• Extends imaging time when the moon is up

Technical Data:

Basic Substrate: Schott optical substrate

Filter Thickness:   2mm+/-0.05mm for up to 2" and 3mm for 50mm unmounted

FWHM (Full width at half maximum): 3nm

CWL (Central Wavelength): 656.3nmnm

Peak Transmission: ＞88% for Ha and SII, ＞85% for OIII

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