SHO in OPTOLONG SHO FILTER KIT stands for SII, H-Alpha, OIII narrow-band filters, generally working with astronomical monochrome cooling CCD and modified DSLR imaging in each single-channel . Corresponding with RGB channel (Ha, OIII, SII), photographers can process Hubble images by astronomical post processing software. The OPTOLONG SHO FILTER KIT contains one H-ALPHA 7NM, one SII 6.5NM and one OIII 6.5NM filter.
The OPTOLONG 7NM H-ALPHA FILTER is the most popular narrowband filter allowing 7nm bandwidth of light centered on a wavelength of 656nm.
The narrowband OPTOLONG 6.5NM OIII FILTER is designed for nebula observation allowing 6.5nm bandwidth of light centered on a wavelength of 500nm.
The Optolong Sulfur-II 6.5nm Extra-Narrowband Filter transmits a 6.5nm bandwidth of light that is centered at 672nm and drastically reduces other transmissions, including wavelengths of light that are responsible for light pollution (both artificial and natural).
All of the Optolong Filters blocks infrared wavelengths from 700nm to 1100nm so you don't need a separate IR-Cut filter.
Hubble look of images can be made by the combination of H-alpha, OIII-CCD and SII-CCD, such as the famous “Pillars of Creation” (M16 Eagle Nebula). Narrowband imaging with SHO set (H-alpha, OIII-CCD and SII-CCD) can be done with the moon up in heavy light pollution, so your equipment is not sitting dormant for several weeks. H-alpha filter is the first narrowband addition to LRGB set for most imagers who blend a black-and-white Ha image into RGB data to enhance structural detail while maintaining natural look.
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: The filters of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.
Thickness 2.0 mm
Surface Quality: 60/40 (Refer to MIL-O-13830)
Fine-optically polished to ensure accurate 1/4 wavefront and <30 seconds parallelism over the both surfaces
OIII transmission:90% transmission at major OIII line 495.9nm and 500.7nm
SII transmission: 80% transmission at SII line 672nm Infrared wavelength 700-1100nm cut-off
H-alpha transmission: 80% transmission at H-alpha line 656nm, infrared wavelength 700-1100nm cut-off
Precision off-band blocking, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm)
Non-cementing optical substrate coating
Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL(central wavelength) no deviation affected by temperature change
Aerometal Material | Precise CNC Machining | Sand Blasting Process | Black Anodized Finish | Extinction Treatment to Prevent Reflection | Laser Engraving No Fading