Περιγραφή
The 4.5nm H-Alpha filter can be used in areas with a lot of light pollution to obtain a very well contrasted and perfectly centered image in the wavelength of 656.3nm.
Antlia’s narrowband has extremely high transmission, allowing for superior contrast while reducing light pollution from artificial sodium and mercury lights.
Contrast makes it possible to see subtle colors separately from the deep sky, the narrower the filter the greater the contrast.
The T is kept stable at 656.3nm with a signal of 95%, where the filter becomes more sensitive to the spectrum to ensure the best Signal-to-noise Ratio and a cut-off rate of OD3 (0.1%) is necessary to reduce interference from other wavelengths.
The H-Alpha filter is commonly used to photograph emission nebulae, planetary nebulae and supernova remnants, it can easily highlight the H-Alpha details of these objects.
Compared to the classic or PRO version, the EDGE version offers a bandwidth of 4.5nm instead of 3.5nm, particularly suitable for very short focal lengths, less than F/4.5.
A 4.5nm narrow band for your CMOS
Antlia Filters has developed the 4.5nm EDGE Ha-OIII-SII series with next-generation CMOS cameras in mind, both the narrowband and V-LRGB series are specifically developed with the needs of CMOS cameras in mind, as well as the use of very short focal lengths, down to F/3.0.
The NarrowBand of Antlia filters is very narrow, only 4.5nm so the result is a minimal amount of light, therefore it is recommended to use these filters on large diameter telescopes, telescopes with a high focal ratio or to take long exposures to get enough signal for the details of the faintest objects.
Production process
The manufacturing process of Antlia filters undergoes the highest standard of controls. Each filter is individually checked, tested and analyzed to ensure it meets the required parameters.
In particular, the filter substrate must have a maximum tolerance of +/- 0.05mm, a very high control standard.
In fact, when light passes through an optical material, it is refracted and the thickness of the glass influences the angle of refraction.
All Antlia filters are parfocal with a maximum tolerance of +/- 0.05mm.
All narrowband filters are blackened at the edges, this process is done manually and is extremely labor intensive, however it is the only way to guarantee a filter free from edge reflections.
Another extremely important data is the cut-off rate of these filters; many users are extremely focused exclusively on the transmission value of the filters and neglect the cut-off rate.
The latter is an extremely decisive quality index, usually not released by other brands on the market, as its production is very difficult, requires very sophisticated machines, constant control and a long production process.
This results in an extremely dark background and minimizes halos around bright stars.
Spectral curve
Main usage and performance
They work very well with monochrome or color CCD and CMOS cameras, CMOS cameras are recommended
Suitable for deep sky imaging of emission nebulae, planetary nebulae and supernova remnants
Extremely high transmission, over 95%
