Askar Filters Colour Magic D2 Duo-band Filter 2" (ASKAR DUO-BAND D2)

The Askar Colour Magic D2 Duo-band 2" Filter is a high-quality imaging filter designed to significantly enhance the contrast and detail of nebula photographs, even under heavy light pollution.

This filter transmits light from ionized oxygen (OIII) and sulfur (SII). Capturing both spectral ranges at the same time allows astrophotographers to produce excellent images without relying on filter wheels or multiple separate filters. Compared with the Askar Color Magic C2 Duo-band 2" filter, the D2 version features a narrower passband and a much higher equivalent optical density for blocked wavelengths.

The Askar Colour Magic D2 Duo-band 2" Filter is not recommended for visual observing. It must never be used as a solar filter.

Key Features of the Askar Colour Magic D2 Duo-band 2" Filter

• Transmittance above 85% for both SII and OIII bands

• Passband half-widths of 6.5 nm (OIII) and 8.5 nm (SII)

• Excellent suppression of mercury and sodium lamp emission lines thanks to an equivalent optical density of OD5

• Ideal for imaging emission nebulae and planetary nebulae

• Suitable for very fast astrographs

Included in the Set

• Askar Colour Magic D2 Duo-band Filter 2"

Technical Parameters

• Filter type: Dual-band

• Filter diameter: 2"

• Filter thickness: 1.85 ± 0.05 mm

• Filter shape: Round

• Transmitted bands: SII, OIII

• OIII central wavelength (CWL): 500.7 nm

• OIII half-width (FWHM): 6.5 ± 0.5 nm

• OIII maximum transmission: >85%

• SII central wavelength (CWL): 672 nm

• SII half-width (FWHM): 8.5 ± 0.5 nm

• SII maximum transmission: >85%

• Blocked wavelengths: Mercury (435.8 nm, 546.1 nm, 577 nm, 578.1 nm) and sodium (598 nm, 589.6 nm, 615.4 nm, 616.1 nm)

• Equivalent optical density for blocked lines: >OD5 (200–1000 nm)

• Surface quality: 60/40

• Parallelism: 30"

Warranty

24 months