These filters are made from quartz glass which has an ultra-low thermal expansion coefficient and outstanding thermal and mechanical properties. Utilizing Antlia's precisely-controlled advanced coating process, these filters are exceptionally durable and can withstand the most challenging environmental conditions, making them ideal for remote observatories.

Compared to the 3nm Pro series, the 2.8nm Ultra filters have a higher transmittance with Ha/SII at ≥97% and OIII at ≥95%. This results in a much higher signal to noise ratio and excellent contrast. To even further enhance the contrast, and suppress the stray light and internal reflections, Antlia applies edge-blackening coating on each filter.

The maximum transmission of the Hydrogen Alpha line (656.3 nm) is 97% within 1nm of the centre bandwidth with a flat-top spectral profile, minimizing loss in transmission due to CWL-shift. For best optical performance, the 2.8nm filters are recommended for use with telescopes that have a focal ratio of ≥f/3.5.

Out of band blocking specification is an exceptional OD5 (0.001%), blocking interference from other wavelengths and minimizing halos around bright stars.

Every single filter is individually scanned to ensure a high quality standard, and the included test sheets included in the box are the actual measured spectra and transmission. The tight tolerance of the filters substrate assure a maximum deviance of ±0.05 from specifications, important for parfocality.

The filter cuts off the ultraviolet and infrared light so there is no need to use a UV/IR-cut filter. The quartz glass substrate and improved coatings make these filters more resistant to fractures and scratches.

Specifications:

DO NOT LOOK AT THE SUN WITH THE ANTLIA FILTERS. Serious eye damage will occur.

Antlia: Experts in Astronomy Filters

Antlia Astronomy Filters are built by Deep-Sky Photography Enthusiasts for Enthusiasts of Astrophotography all around the globe. Antlia prides itself on producing a series of exceptional quality, fully multicoated narrowband, dual-band, planetary and LRGB filters for astrophotography, designed for use with a range of monochrome and colour DSLR, CMOS and CCD cameras.

Product Code: ANT-H-Alpha2.8