The He-II filter reveals the emission line of ionised helium at a wavelength of 486 nanometres. This line is not usually visible with h-alpha and O-III filters. In this line, structures become visible that are located in regions surrounding bright radiation sources, for example planetary nebulae around hot white dwarfs with a surface temperature of several tens of thousands of kelvin.
The Astronomik filters supplied with the QHY Camera miniCam8 Mono Combo have been specially developed for this camera and the connected filter wheel. They are optimised for astrophotography. You can supplement the filter set supplied with the camera with this filter.
