- 2" O-III Filter greatly enhances contrast during visual observation of gaseous and planetary nebulae in all sky conditions. Astrophotographic 2" filter allows high-contrast imaging even in areas with strong light pollution.
- Especially useful for large aperture telescopes through which the light of the Moon can be extremely overwhelming. Allowing just for the Double Ionized Oxygen lines between 496mm to 501nm to pass through at 95%.
- Completely blocks virtually all other visible wavelengths of light so views of nebulas are optimized. Increases contrast through selective filtration-Anti-reflection coated to prevent glaring and ghosting.
- Not only useful at light-polluted sites; the contrast is also increased at dark sky sites, can be used with all 2" eyepieces. Filter made from high-grade glass with dichroic interference and antireflection coatings.
- Each Astromania 2" O-III Filter is individually inspected and proudly inscribed with the percentage of light transmittance of the two O-III emission lines.
The Astromania 2" O-III Filter is comparable to the Astromania UHC filter in its function. The difference is that this filter only allows the light of doubly ionized oxygen through. This means that there is an enormous increase in contrast with diffuse, planetary and extremely dim nebulae. This is a special narrowband filter which allows an even smaller range of wavelengths than the Astromania UHC filter. Even so, there are innumerable astronomical objects which can be first observed in detail with this filter or cannot be seen at all without it. A prime example is the Veil nebula in the constellation of Cygnus. It's a great accessory for observations of nebulae due to its capability to suppress all light that lies outside its 4960-5010 angstrom (496-501 nm) passband. This filter can be used for astrophotography as well. The O-III 2" Filter has a standart barrel diameter so you can use it with a telescope of any brand. Note that this filter gives a green tint to observed objects. The O-III provides an even greater contrast boost on some objects than the UltraBlock narrowband filter. And for nebulas, every little bit helps! It substantially improves contrast and outperforms the UHC for most planetary nebulae while on apertures of 10" or more, it outperforms the UHC filter for all types of nebulae. The Astromania 2" O-III Filter isolates just the two doubly ionized oxygen lines (496 and 501nm lines) emitted by diffuse, planetary and extremely faint nebulae. Thus, these faint objects become much more visible against the blackened background of space. The Astromania 2" O-III Filter produces near-photographic views of the Veil, Ring, Dumbbell and Orion nebula, among many other objects. Performs well under both light-polluted and dark skies.