The Antlia S-II 4.5nm Edge 1.25" narrowband filter has the same excellent transmittance characteristics as their 3nm Pro series but at a more affordable price.
The 4.5 nm bandpass is only 1.5% of the entire visible spectrum, increasing the signal to noise ratio and delivering high contrast images and extremely dark backgrounds. 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 Sulphur II line (671.6 nm) is above 90% within 1nm of the centre bandwidth.
Blue-shift data shows that Antlia Edge 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.
Each filter is individually tested to ensure a high quality standard. The tight tolerance of the filters substrate assure a maximum deviance of ±0.05 from specifications making these filters parfocal.
The filter cuts off the ultraviolet and infrared light so there is no need to use the IR-cut filter.
DO NOT LOOK AT THE SUN WITH THE ANTLIA FILTERS. Serious eye damage will occur.
|Passing band||4.5 nm (FWHM)|
2.0 mm ±0.05
1/4 λ (wavefront)
|Off-band transmission||OD5 @ 300-1050 nm|
|Coating||Double-sided multilayer nano-coating|
|Surface quality||60/40 (in accordance with US military watch MIL-O-13830)|
|Glass type||Monolithic optical substrate (non glued)|
|Filter size||Mounted 1.25"|
|SKU 2" filter