This H-alpha 3nm Pro narrowband filter is the upgraded version of the Antlia H-alpha 3.5nm filter. The narrower bandwidth of this filter enhances the contrast of nebulae that emit H-alpha by decreasing transmission of out-of-band wavelengths from light pollution, the moon, and chromatic aberration of bright stars. The filter rejects out-of-band wavelengths by up to 5 OD (99.999%).

This filter is suitable for imaging most emission nebulae, planetary nebulae and supernova remnants with monochrome astronomy cameras. It can bring out a tremendous amount of detail in nebulae where H-alpha emission is present. Because the filter passes little light outside the H-alpha band, longer exposure times and larger apertures or faster focal ratios may be necessary.

The H-Alpha 3nm Pro filter is designed to deliver >90% transmission at the center wavelength of 656.3nm. The transmission of the H-alpha 3nm Pro over its working bandwidth guarantees high transmittance when working with both long focal ratios and fast optical systems (as fast as f/3).

For the H-alpha 3nm Pro narrowband filter, we use latest coating technology to achieve 5 OD (0.001%) out of band blocking. Each filter is individually tested and scanned to ensure that product quality meets our high-performance parameters. The end result is a filter that achieves excellent contrast but with a price-to-performance ratio that compares more favorably than similar premium filters in the market.

Features:

    Extra narrow 3nm bandwidth for superb contrast and ability to record the faintest H-alpha nebula detail
    > 5 OD (0.001%) (out of band blocking) @300-1000nm
    Steep spectral profile minimizes halos around bright stars
    Peak transmittance guaranteed >90% at the emission line 656.3nm to increase the contrast in the shortest possible imaging time
    3nm Pro Narrowband filters are coated to the edge of the part and are edge blackened to minimize reflections and stray light
    A single substrate to eliminate internal reflections
    3nm filters can be used with fast optical systems to f/3 with only slight loss of signal
    Parfocal with Antlia LRGB, SII and OIII filters (telescope optics need additional consideration)
    The Ha filter can be used with SII,OIII set of filters to achieve the impressive Hubble color palette
    Superior optical reliability reduces post image processing
    This filter is not suited to deep sky objects that do not contain Ha emissions
    NOT SAFE FOR USE AS A SOLAR FILTER

Specifications:

    Substrate: 1.25’’ mounted (2mm+/-0.05mm)
    Surface Quality: 60/40 (Refer to MIL-O-13830)
    2 sides fine-optically polished to ensure accurate 1/4 wavefront
    30 arc second parallelism
    Center-Wavelength of Antlia H-Alpha 3nm Pro filter: 656.3nm
    H-Alpha 656.3nm T＞90%, 90% transmission at H-Alpha line 656.3nm
    > 5 OD(0.001%) @ 300-1000nm
    2 sides multi-layers anti-reflection coating
    Single / Non-glued substrate

Filter Ring:

    1.25’’ (M28.5x0.6)
    Ultra-thin filter cell to minimize vignetting
    Black anodized finish
    Laser engraving No fading

Not Recommended:

    Visual observation
    DO NOT LOOK AT THE SUN WITH ANTLIA FILTERS