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Astronomy > Filters > Nebulae filters > SII Filters > Astronomik > SII 12nm > Astronomik Filters SII 12nm 31mm
Product no.: 67126

Filters SII 12nm 31mm

$ 193.00 incl. VAT plus shipping costs
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  • Increases contrast when photographing SII regions
  • Additionally blocks infrared light
  • Also suitable for fast optics up to f/4

Product description

The SII filter increases the contrast between SII regions and the sky background. Due to its narrow half-width and high transmission of almost 100% in the SII line, the filter achieves a significantly greater contrast increase than broadband filters. The half-width of 12nm is optimally matched to the use of typical CCD and CMOS sensors.

Even in large cities, images taken with cooled cameras are usually limited by dark current. Therefore, further suppression of the sky background by lower half-widths does not reveal more details in the object. Compared to very narrow-band filters, the H-alpha 12nm filter has the advantage that you can usually find guide stars for almost all cameras with built-in tracking sensors.

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 6nm half-width are interesting if you want to photograph objects in very starry areas of the sky with short focal lengths, if you have a camera with very low dark current or if you are observing from a location with extreme light pollution. The number of stars in the image is typically halved.

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.

Specifications

Capacity


Central wavelength (nm)
672
Half-value width (nm)
12
Frame
ring
Mount material
Aluminium
Coating of optical system
MRF
Filter Size (mm)
31

General


Type
Filters
Type of build
line filter
Series
SII 12nm

Area of application


Visually useful
no
Useful for photographs
yes
Anti light-pollution
yes

Product safety

Manufacturer: astro-shop, Eiffestr. 426, 20537 Hamburg, DE, www.astro-shop.com
Astronomik Filters SII 12nm 31mm
Light transmission curve

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