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