Astronomik H-alpha 12nm

The Astronomik H-alpha filter is a narrow band filter for CCD photography. The filter lets the H-alpha light of emission nebulae pass and blocks nearly the whole remainder of the spectrum where 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. read more...

The full width at half-maximum (FWHM) of 12nm is optimized for the use with common CCD cameras and allows the use of very fast optics. It should be noted that the filter has a transmission of up to 99%.

Another advantage of the 12nm filters is the 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 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.

Main use

The Astronomik H-alpha-CCD (12nm version) increases the contrast between objects, in this case between the H-alpha emission line and the skyglow background. Our Astronomik H-alpha-CCD (12nm version) completely suppresses the emission lines of artificial lighting (mercury (Hg) and sodium (Na)) and skyglow.

Other uses

When using the OIII CCD and the SII-CCD 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 a color image.
The Astronomik 6nm H-Alpha filter may NOT be used for solar observation.
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: Reasonable, but very long exposure times
CCD photography: Verry good, huge contrast enhancement at H II-emission nebulas
DSLR photography (original): Good, reduced sensitivity in the H-alpha band
DSLR photography (astro modified): Verry good, huge contrast enhancement at H II-emission nebulas
DSLR photography (MC modified): Verry good, huge contrast enhancement at H II-emission nebulas
Webcam / Video (Planets): Unsuitable
Webcam / Video (Deep Sky): Good, good contrast enhancement with bright objects

Technical Data

Transmission of over 97% with the H-alpha line (656nm)
Complete blocking from all disturbing wavelengths in the infrared
Parfocal with other Astronomik filters
Glass thickness: 1mm
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