Baader SII 1.25" Ultra-Narrowband CMOS Optimized 4nm Filter

Baader SII 1.25" Ultra-Narrowband CMOS Optimized 4nm Filter

Baader Plentarium has designed this 1.25" SII ultra-narrowband filter to be precision-grade and provide astrophotographers an excellent complement to their imaging setup. SII filters are suitable for imaging cosmic bodies like nebulae that are along the singly ionized sulfur (SII) wavelengths. This narrowband filter works well both in conditions of light pollution or dark skies! SII filters block all wavelengths from UV to infrared, including the emission lines of sodium/Na and mercury/Hg artificial lighting, except for the SII singly ionized sulfur wavelengths which occur as a doublet at 671.7 nm and 673 nm.

With 4 nm FWHM, this filter from Baader is ultra-narrowband and is recommended for extremely fast optical systems from f/10 to f/3.5. The filters are designed to allow for 1:1:1 exposures. This matches the typical CMOS quantum efficiency and s/n ratio.

This Baader Planetarium SII ultra-narrowband filter is CMOS optimized with Life-Coat. This coating is a hard coating that will not peel, flake, and will not physically degrade even in the most extreme weather conditions. This coating is also designed to withstand repeated cleaning with fine optical cleaning equipment. This coating is so durable that Baader is confident it will last the life of the filter.

Not only do the filters have sealed coating edges with the Life-Coat, but they are also individually hard coated with Reflex-Blocker and planoptically polished. All of the edges are blackened for increased contrast and eliminate any reflection that would come from light falling on the edge of the filter. The filters are also equipped with a filter-lead-side-indicator in the form of a frontside outer rim. The filters are optimized for CMOS cameras, but they work great with CCD cameras as well.

Baader Ultra-Narrowband 1.25" CMOS Optimized Filter Features

• Transmission Ranges: SII

• Filter Thickness (w/out glass) 2 mm

• Half Bandwidth: 4 nm

• Central Wavelenth: 671.7 nm

• AR-Coating: Reflex Blocker hard coated and planoptically polished

• Filter Size: 1.25"

• Threaded: Yes

• Usage: CMOS, CCD, SII

• Mounted: Yes

• Filter Type: Narrowband

• Filter Shape: Round

• Feature Highlight: CMOS-Optimized with Life-Coat