iOptron SII Narrowband Filter -1.25"

An improved narrowband SII filter (Sulfur II for CCD) is designed for nebula observation. The filter isolates the light at the wavelength of 672nm. It allows it to pass through and reduces the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).

Narrowband filter do not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.

WARNING: iOptron filters are not designed for direct solar observation. NEVER use these filters for observing or imaging the Sun, or permanent eye and equipment damage will result.

• 1.25" mounted filter for 1.25 in filter wheel, such as iEFW-15
• Can be used for a 1.25" eyepiece (M28.5X0.6)
• Multi-layer anti-reflection coating for high transmission
• High surface quality of 60/40
• Surface flatness <λ/4
• Parallelism 30"