Astronomik Filters SII 6nm CCD T2

In contrast to purely visual filters, photographic CCD filters have built-in IR-blocking, which prevents the optical problems caused by infrared radiation.

MRF-coating: thanks to the new MFRF coating technology, it is possible to use the filter on all devices up to an aperture of f/4.

Alternative: The line filters with 12nm full width at half maximum are interesting if you are using a DSLR or a CCD camera with a higher dark current. The 12nm filters are also the best choice if your camera has a built-in guiding chip, because when using the 12nm filter you typically have twice as many stars in the image.

A bit of help with your selection:

• As a first filter, we recommend the Astronomik CLS filter. This filter suppresses artificial light pollution and natural airglow. By using this filter you get a dark-sky background and can therefore use much longer exposure times to make fainter objects visible. The filter is optimised in such a way that objects are reproduced in their natural colours. Important: the simple CLS filter has no built-in IR-blocking. Therefore you will need the CLS-CCD filter for an astro-modified camera!
• A good choice for working in locations with really heavy light pollution is the Astronomik UHC filter. The transmission curve of this filter only allows the light of the H-beta, OIII, H-alpha and SII lines to pass through. The background suppression is significantly stronger than with the CLS, however this filter works only for gas nebulae! Star clusters and galaxies are largely filtered out.
• For a more in-depth introduction to astrophotography, we recommend the OIII, H-alpha and SII emission lines filters, available with full width at half maximum of 6nm or 12nm. With these filters you can create detailed images of faint objects even from locations with extreme light pollution and a full Moon high above in the sky. Images in these narrow emission lines are not naturally coloured.
• For the owners of astro-modified cameras we offer the Astronomik OWB filter: OWB stands for “original white balance”. The filter corrects the displaced colour reproduction of a converted camera so that it can also be used for normal every-day photography, without having to revise every image on the computer.