SII filters: The narrow-band filter allows light from ionised sulphur atoms at 650 nanometres to pass through. This is the line in which many planetary nebulae, emission nebulae and supernova remnants shine.
Astrophotography: Monochromatic cameras are best used. Ideally, combine shots with SII, OIII and H-alpha filters. This results in an image that shows the delicate nebula structures in high contrast and clearly.
Line filters with a 12 nanometre half-width are useful if you are using a DSLR or a CCD camera with a higher dark current. The 12 nm filters are also the first choice if your camera has an integrated guiding chip, because when using 12 nm filters, you typically have twice as many stars in the image.
