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Optolong H-Alpha 7nm CCD Filter - 1.25" Mounted - HAL7-125
Optolong H-Alpha CCD 7nm Filter - 1.25”
The Optolong H-Alpha 7nm is an extremely narrow emission-line filter that works by allowing a 7nm bandwidth of light, centered on the 656nm wavelength through, and blocking the transmission of contrast-killing light pollution wavelengths. Wavelengths that are responsible for natural light pollution, or skyglow, are drastically reduced, as is artificial light pollution caused by high and low pressure sodium vapor and mercury vapor lights. The result is a high contrast image that reveals the H-alpha line in all its glory.
This Optolong H-Alpha filter will provide the ultimate in contrast between the skyglow background and H-alpha emitting objects, but because it has a FWHM of just 7nm, you won’t see as many stars in the final image as you would with the Optolong 12nm H-Alpha Filter. Use this filter alone for CCD or DSLR imaging, or use together with OIII 6.5nm and SII 6.5nm filters to get a tricolor image of gaseous nebula from light polluted skies. Like all Optolong filters that are designated as “CCD”, this H-Alpha filter also blocks infrared wavelengths from 700nm to 1100nm so you don't need a separate IR-Cut filter.
The Optolong 1.25” H-Alpha 7nm Filter is made with Schott glass that has been multi-coated with an ion-assisted deposition technology to ensure scratch resistance and stability on the central wavelength, or CWL. The filter cell is made of lightweight, strong metal and is CNC machined, sand-blasted, black anodized, and then laser engraved. The result is a super thin filter cell that will produce a clear aperture of 26mm.
Please Note: This h-alpha filter is NOT for use on the Sun. To do so could cause irreparable eye damage or blindness. Don’t even think about it!
Quality Filter Materials:
- Schott B260 substrate material from Germany, 2.0mm thick
- CNC machined and black anodized aero-metal filter cell that is ultra-thin to provide largest clear aperture; Laser-engraved to prevent fading
- Multiple layers of anti-reflection non-cementing coatings applied via electron-beam gun evaporation with Ion-assisted deposition
Optolong Filter Manufacturing Processes and Parameters
- Filter substrate is fine-optically polished to 1/4 wave and <30 parallelism over both surfaces
- Surface quality, according to MIL-O-13830, is 60/40
- 80% transmission at H-alpha 656nm
- Infrared wavelength of 700-1100nm is cut off
- 0.1% transmission Hg at 435nm and 578nm
- 0.1% transmission Na at 589nm
- High value transmission of pass-band and optical density of off-band is assured through Optolong’s planetary rotation system, a homogenous and precise coating procedure
- Thin metal cells have a clear aperture of 26mm for 1.25” filters
- Each filter comes with a plastic case with high pressure EVA case lining
Optolong is the Astronomy Filters division of Yulong Optics, an optical filter design and processing company out of Kunming, China that has provided filters for over 700 optical companies since 1999. All Optolong filters pass European Union RoHS requirements and have been certified by TUV Rheinland and Bureau Veritas.