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Home > Filters > Nebulae filters > SII Filters > Astronomik > SII CCD > Astronomik Filters 2" SII CCD filter

Astronomik Filters 2" SII CCD filter

Product no.: 16763
Manufacturer: Astronomik

$ 330.00

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Astronomik Filters 2" SII CCD filter
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Product description:

Astronomik SII 12nm Filter

The Astronomik SII-CCD filter is a narrow-band-filter for CCD photography.The filter lets the light of the ionized sulfur (SII) pass, and blocks nearly the whole remainder of the visual spectrum as well as IR, in which the CCD is sensitive.

We have re-desgined all of our photographic filters. Since the end of 2008 we are shipping our new "Halo-Free" filters.

The full width at half maximum (FWHM) of 12nm is optimal suitable for common CCD cameras and allows the use of very fast optics. The range of application extends from 1:2.8 to 1:15. Transmission losses and chromatic distortions, which arise with other filters, only occur with Astronomik filters when extremely bright aperture ratios of 1:2 and more come into play. It should be noted, that the filter has a transmission of up to 99%.

Another advantage of the 12nm filters is the good availability of guiding stars for cameras with a built-in-autoguider (SBIG). If you use a very strong filter like our 6nm filter you often won't find a usable guidestar.

The Astronomik SII CCD filter increases the contrast between objects, in this case between those with SII emission lines and the skyglow background. Also, our Astronomik SII-CCD filter completely suppresses the emission lines of artificial lighting (mercury (Hg) and sodium (Na)) and skyglow.

Main use

The Astronomik SII CCD increases the contrast between objects, in this case between the SII emission line and the skyglow background. Our Astronomik SII CCD completely suppresses the emission lines of artificial lighting (mercury (Hg) and sodium (Na)) and skyglow. Due to the high optical quality of the Astronomik H-alpha-CCD substrate you will see the same needle-sharp stars as you would from your regular telescope.

How do I interpret these transmission curves?

  • the wavelength is plotted in nanometers on the horizontal axis. 400nm corresponds to deep blue, 520nm to green and at 600nm to red
  • transmission, in %, is plotted on the vertical axis
  • visual filters: The gray curve shows the relative sensitivity of the dark adapted human eye at night
  • photographic filters: The gray curve shows the relative sensitivity of a typical CCD sensor
  • orange: the main emission lines which contribute to artificial sky glow, e.g lines from mercury (Hg) and sodium (Na)
  • green: the most important emission lines from nebulae, such as the lines from hydrogen (H-alpha and H-beta) and the lines from oxygen (OIII)

17.10.2019
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