ZWO 36mm H-alpha SII OIII 7nm Filter Set

The ZWO 36mm H-alpha SII OIII 7nm Filter Set allows only Hydrogen, Oxygen, and Sulfur emissions to be photographed. These filters will enhance contrast for these wavelengths and block most wavelengths produced by city lights. Narrowband filters will reduce the transmission of most wavelengths and only allow certain ones narrow bands to pass.

Technical Data of the ZWO 36mm Filter Set

• FWHM: 7±0.5nm.
• Glass Thickness 2.0+/-0.03mm  (1.25 inches/ 31mm/ 36mm).
• Fine-optically polished to ensure accurate 1/4 wavefront over the both surfaces.
• About 90% transmission at H-alpha line 656nm (H-Alpha filter).
• About 90% transmission at SII line 672nm (SII filter).
• About 90% transmission at major OIII line 500nm (OIII filter).
• Infrared wavelength 700-1100nm cut-off.
• <0.1% transmission of off-band, OD3 (Optical Density).

Transmission Curve

• Observe increased contrast between nebula and the night sky, without brightening the nebula. 
• Each polished to reach an accurate one-fourth wave.
• Multi-layered anti-reflection coatings.

• H-Alpha filter.
• SII Filter.
• OIII Filter.
• Case x3.