Astronomik SII 4nm Filter 36mm (SKU: 8h11uq / 10204336) all astro filters opinie

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Astronomik SII 4nm 36 mm Filter is a narrowband emission line filter designed for imaging nebulae emitting light in the ionized sulfur SII lines at wavelengths of 671.7 nm and 673.0 nm. It significantly enhances nebular contrast relative to the sky background under both light-polluted and dark sky conditions.

Key features

• selective transmission of SII emission lines (671.7 nm and 673.0 nm)
• very narrow 4 nm bandwidth for maximum background suppression
• effective blocking of sodium (Na), mercury (Hg) vapor lamps, natural airglow and most moonlight
• high contrast imaging of sulfur-rich nebulae under heavy light pollution
• complete blocking of unwanted light from UV to IR
• suitable for HSO (H-alpha, SII, OIII) narrowband imaging

Astrophotography applications

• imaging sulfur emission nebulae
• complementing H-alpha and OIII filters in narrowband filter sets
• operation under heavy light pollution and bright moonlight
• imaging faint targets in dense Milky Way star fields

Differences between Astronomik SII filters

• 4 nm version: maximum background suppression, recommended for very low dark current cameras and extremely light-polluted sites
• 6 nm version: balance between background suppression and guide star availability
• 12 nm version: designed for DSLR cameras and CCD sensors with higher dark current

Astronomik MFR and MaxFR coatings

• MFR coating: full UV–IR blocking, extremely high contrast, no reflections or halos
• SII 4 nm with MFR coating: recommended for optical systems from f/4.5 to f/15 without significant transmission loss
• MaxFR coating: optimized for very fast optical systems (4 nm version currently under development)

Technical specifications

• filter type: narrowband SII emission line filter
• bandwidth (FWHM): 4 nm
• SII wavelengths: 671.7 nm and 673.0 nm
• guaranteed transmission: >90% at both SII lines
• typical transmission: 93%
• blocking range: UV to IR
• glass thickness: 1 mm
• diameter: 36 mm (unmounted)
• material: finely polished optical glass free of striae and internal stress
• coating: Astronomik MFR
• parfocal: yes, with other Astronomik filters
• optical quality: diffraction limited
• durability: resistant to humidity and aging effects
• quality control: individually measured with a PerkinElmer spectrophotometer
• manufacturer: Astronomik
• SKU: 8h11uq / 10204336