Optolong H-Alpha 7nm Narrowband Filter
Optolong improved version of H-Alpha 7nm filter is the popular narrowband filter allowing 7nm bandwidth of light centered on a wavelength of 656nm through, and reducing the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). Better choice of narrowband H-alpha astrophotography filter for highest contrast and revealing subtle nebula details.
Main use and performance:
Suitable for viewing on faint emission nebula of H-Alpha line in full moonlight or in severe light pollution.
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.
※This curve is only for reference, and is not used as the final product data.
How to read the chart?
▲The horizontal axis is the Wavelength in Nanometers(nm).
▲The vertical axis is transmission in %.
·Multi-layers anti-reflection coating
·Non-cementing optical substrate coating
·Optolong filter adopts precision coating based on 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.
·Planetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and Optical density of off-band.