ANTLIA Narrowband 4.5nm H-alpha EDGE Filter - 31mm Unmounted (glass only)

Application and Performance:

• High transmittance and narrow bandwidth to maximize contrast
• Steep spectral profile minimizes halos around bright stars
• A single substrate to eliminate internal reflections
• Narrowband Objects: H-alpha 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
• Antlia narrowband EDGE filters can be used down to f/3 systems with minimal loss of signal
• Edge blackened to eliminate internal reflections from stray light
• Superior optical reliability reduces post image processing
• This filter is only effective for deep sky objects that contain H-alpha emissions

Technical Specifications:

• Basic Substrate: Optical, Single / Non-glued substrate
• Filter Thickness: 2mm+/-0.05mm for 1.25”, 2” mounted, Dia31mm and Dia36mm unmounted; 3mm+/-0.05mm for Dia50mm unmounted
• FWHM (Full width at half maximum): 4.5nm
• CWL (Central Wavelength): 656.3nm
• Peak Transmission:＞90%
• Blocking: > 5 OD (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

Filter Cell:

• 1.25’’ (M28.5x0.6), 2’’ (M48*0.75)
• Ultra-thin filter cell to minimize vignetting
• Black anodized finish
• No fading laser engraving

Available Sizes：

• Mounted： 1.25’’， 2’’
• Unmounted：Dia31mm，Dia36mm，Dia50mm

Not Recommended:

• Solar Observing and imaging
• Visual observation

Warranty: 3-years against delamination

DO NOT LOOK AT THE SUN WITH ANTLIA FILTERS. Serious eye damage will result if you fail to observe the warning.

When Antlia design filters for astronomy imaging systems, they look at how they will work together with optical systems,carefully designing the out of band blocking rate, transmittance and band-pass parameters to achieve an optimum result. Each filter is individually tested and scanned by strict QC to ensure that the quality meets the high-performance parameters. The result is that Antlia is known for designing filters for astrophotography that achieve exceptional quality and performance parameters at affordable prices. We believe the price to performance ratio compares more favorably than similar premium filters in the market.

IMPORTANT NOTE: 

No returns of Antlia narrowband filters are accepted due to halos appearing around brigth stars.

Antlia made huge efforts to minimise halos around bright stars and achieved very good results by doing so, therfore you will most likely rarely if ever see halos, however this is a very complicated topic as halos can be caused by varios elements in the optical train. There are thousands of possible scenarios and they simply cannot promise that there will be no case when some level of haloing will appear.  The Antlia filters are extremely good and represent very good value, but only much more expensive filters (like Astrodon and Chroma) are likely to provide halo-free images. We also supply these filters, however in most cases Antlia filters would offer a near-to-perfect solution.