Baader 3.5/4nm Ultra-Narrowband 2" CMOS Optimized Filter Set - Ha, OIII, SII

Baader 3.5/4nm Ultra-Narrowband 2" CMOS Optimized Filter Set - Ha, OIII, SII

Included in the filter set are three precision-grade 2" threaded filters: an H-alpha filter, an SII filter, and an OIII filter. With 3.5nm and 4 nm half bandwidth to harmonize the exposure time of the H-alpha with the OIII and SII filters, these filters from Baader are recommended for extremely fast optical systems from f/10 to f/3.5, like the Celestron RASA astrographs. The filters are designed to allow for 1:1:1 exposures. This matches the typical CMOS quantum efficiency and s/n ratio. The filters enable the high contrast, even in high levels of light pollution, minimize the size of the starts, and allow the finest details of nebulas accessible.

This Baader Planetarium ultra-narrowband filter set is CMOS optimized with Life-Coat, a hard coating that will not peel, flake, or physically degrade and will 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, even in the most extreme environments.

Not only do the filters have sealed coating edges with the Life-Coat, but they are also 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 well with CCD cameras too.

About the H-alpha Filter

H-alpha filters are highly favored when it comes to narrowband filters and are deep red in color. Hydrogen is the most common element in the universe and is present in emission nebula such as the North American and the Pelican, planetary nebula such as the Dumbbell and Ring, Wolf-Rayet objects like Crescent and Thor's Helmet, even supernova remnants like the Veil nebula.

About the OIII Filter

Oxygen III (OIII) narrowband filters isolate just the two doubly-ionized oxygen lines (496 nm and 501 nm lines) emitted by planetary and emission nebulae while blocking the rest of the overall spectrum of light. This results in extreme contrast between the black sky background and the faint photons of OIII light needed for detailed views of the Veil, Ring, Dumbbell, Crescent and Orion nebulae, and other objects.

About the SII Filter

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.

Baader 3.5/4nm Ultra-Narrowband 2" CMOS Optimized Filter Set Features

• Transmission Ranges: H-alpha, OIII, and SII

• Filter Thickness (w/out glass) 2 mm

• Half Bandwidth: H-alpha: 3.5 nm, SII and OIII: 4 nm

• Central Wavelenth: 656.3 nm, 500.7 nm, 671.7 nm

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

• Filter Size: 2"

• Threaded: Yes

• Usage: CMOS, CCD, H-alpha, OIII, SII

• Mounted: Yes

• Filter Type: Narrowband

• FIlter Shape: Round

• Feature Highlight: CMOS-Optimized with Life-Coat