Astronomik - Sulfur II Filter 6 nm, SC thread

The Astronomik SII filter is a narrow-band-filter for astro photography. The filter lets the light of the ionized sulfur [S II] pass, and blocks nearly the whole remainder of the visual spectrum as well as IR, in which the sensor is sensitive.

The full width at half maximum (FWHM) of 6 nm is optimal suitable for common astro 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 6 nm 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 6 nm filter, you often won´t find a usable guidestar.

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

Main use:

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

Other uses:

Using the H-alpha and the [O III] filters, you can obtain three-color images of emission line objects (gas nebulae) from locations with very strong light pollution. To do so, you would take an image in three different wavelengths, select each one as a color-channel in Photoshop and paste them together as one single color image.

If you plan to create color images from emission line data, our CLS-CCD filter is a great choice for the Luminance channel.

Suitability:

Visual observation (dark skies): Unsuitable

Visual observation (urban skies): Unsuitable

Film photography: It depends, but very long exposure times

CCD and CMOS photography: Very good, huge contrast enhancement at [S II]-emission nebulae

DSLR photography (original): Unsuitable

DSLR photography (astro modified): Very good, huge contrast enhancement at [S II]-emission nebulae

DSLR photography (MC modified): Very good, huge contrast enhancement at [S II]-emission nebulas

Webcam / Video (Planets): Unsuitable

Webcam / Video (Deep Sky): Unsuitable

Technical Data:

Transmission of over 97% with the [S II] line (672 nm)

Complete blocking of all disturbing wavelength ranges in the infrared

Parfocal with other Astronomik filters

Glass thickness: 1 mm

Completely resistant against high humidity, scratches and aging effects

Diffraction limited, the filter will not reduce the optical performance of your telescope!

Astronomik filters are delivered in a high-quality, long lasting, filter box