Astronomik SII 12nm CCD T-Mount (M42x0,75) (SKU: 10216042 / 8h00bq) all astro filters opinie

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Astronomik SII 12 nm CCD T-Mount (M42x0.75) Filter (SKU: 10216042 / 8h00bq) is a narrowband filter designed for imaging nebulae with sulphur SII emission. It significantly increases contrast between objects emitting at 671.7 nm and 673 nm and the sky background, both under light-polluted skies and at dark sites. The 12 nm version is designed for use with typical DSLR cameras with CMOS sensors and CCD cameras with normal or high dark current.

The filter selectively transmits the SII emission lines (671.7 nm and 673 nm) while effectively blocking unwanted light at other wavelengths from UV to IR. It fully suppresses emission lines from sodium (Na) and mercury (Hg) lamps, all natural airglow lines, and most interfering moonlight.

In areas with low light pollution, image background is typically limited by the sensor’s dark current rather than sky brightness. Therefore, further background suppression by reducing the bandwidth (smaller FWHM) does not necessarily reveal additional object detail compared to the 12 nm version.

Completing a narrowband set with an SII filter enables false-colour imaging in the HSO (H-alpha, SII, OIII) palette. Compared to the 4 nm and 6 nm filters, the 12 nm version is intended for cameras with normal or higher dark current and is often preferred for cameras with an integrated guiding sensor because it shows more guide stars.

Key features

• narrowband filter for SII emission lines: 671.7 nm and 673 nm
• significant contrast enhancement against the sky background
• complete suppression of sodium (Na) and mercury (Hg) lamp emission lines
• complete suppression of natural airglow lines and most moonlight
• effective blocking of unwanted light from UV–IR
• extremely scratch-resistant, durable coating
• fully resistant to high humidity and ageing effects
• Astronomik MFR coating
• parfocal with other Astronomik filters
• diffraction-limited design
• supplied in a high-quality, durable filter box

Box contents

• Astronomik SII 12 nm CCD T-Mount (M42x0.75) filter
• high-quality, durable filter box

Technical specifications

• emission lines: 671.7 nm and 673 nm
• full width at half maximum (FWHM): 12 nm
• guaranteed transmission: > 90% at both SII lines
• typical transmission: 96% at both SII lines
• blocking range: UV–IR
• glass thickness: 1 mm
• glass: finely polished optical glass, free of striae, internal stress and bubbles
• coating durability: extremely scratch-resistant and rugged
• coating stability: fully resistant to high humidity and ageing effects
• coating: Astronomik MFR
• recommended f-ratio range: f/3–f/∞ (for MFR coating)
• optical quality: diffraction-limited design
• parfocality: parfocal with other Astronomik filters
• packaging: high-quality, durable filter box

Astronomik SII 12 nm is a practical choice for capturing nebular structures in the SII emission lines, combining strong selectivity with effective background suppression under light pollution.