6.5nm SII Narrowband Filter
Optolong
From ~$146.93
3 stores
In stock
The Optolong SII 6.5nm Extra Narrowband Filter offers precise filtration, transmitting a narrow 6.5nm bandwidth centered at 672nm while blocking unwanted wavelengths, including light pollution. The filter can be used in conjunction with H-Alpha and OIII filters for false color emission line images like the Hubble Space Telescope. Due to the narrow bandwidth and high transmission rate, this filter delivers a major boost to contrast, making the sky black with half as many stars visible compared to a 12nm SII. Like all Optolong CCD filters, the SII blocks infrared wavelengths from 700nm to 1100nm so you don't need a separate IR-Cut filter.
Specifications
| Infrared Blocking Range | 700 |
| Substrate Thickness | 2 mm |
| Bandwidth | 6.5 |
| Coating Technology | Ion-assisted deposition with electron-beam gun evaporation |
| Clear Aperture 2 inch | 45 mm |
| Surface Quality | 60/40 |
| Weight (36mm and 1.25 inch versions) | 0.15 kg |
| Filter Type | Sulfur II (SII) |
| Off-Band Transmission | 0.1% |
| Substrate Material | Schott B270 optical glass |
| Wavefront | 1/4 wave |
| Central Wavelength | 672 |
| Parallelism | 30″ |
| Clear Aperture 1.25 inch | 26 mm |
| Optical Density | OD3 |