1.25" Orion Oxygen-III Extra-Narrowband Filter
Now you can capture dramatic Hubble-like CCD images of emission nebulas from the heart of the city or under a full Moon. How? By imaging with the Orion S-II, O-III, and H-alpha extra-narrowband "line" filters. These specialized filters transmit only the specific wavelengths of light that are important in emission nebulas, while blocking out all other light, whether artificial or natural Ñ from street lamps, the Moon, you name it! The result: high-contrast tricolor images from even grossly light-polluted skies.
The Orion O-III filter passes light at the 500.7nm wavelength (the Oxygen-III line) with very high 90% transmission and a bandpass of 7nm. It complements Orion H-alpha and Sulfur-II extra-narrowband filters, which together allow advanced tricolor imaging of emission nebulas with Orion monochrome imaging cameras or similar monochrome cameras.
These 1.25" astrophotography filters are made from high-grade glass and feature vacuum-deposited dichroic interference coatings and antireflection coatings. All three are parfocal, meaning no refocusing is needed when switching among them. Each filter is held in an anodized aluminum cell that is threaded to fit a standard CCD camera 1.25" nosepiece or an Orion multiple filter wheel.
Images taken with extra-narrowband filters typically look much different from those acquired using standard "true color" (RGB) methods. Rather than rendering an image in its "natural" color, the extra-narrowband filters provide a visual representation of the elemental makeup of a nebula, highlighting with assigned colors the areas where the light derives predominantly from either Sulfur-II, Oxygen-III, or Hydrogen-alpha ions. This is the approach used by astronomers for many of the nebula pictures taken with the Hubble Space Telescope. The extra-narrowband "false color" images, while beautiful, also reveal much about the chemical composition of the nebula and its various features.
So if you're ready to go beyond RGB imaging and capture your favorite nebulas in a revealing new light Ñ no matter how light-polluted your skies Ñ add Orion's O-III (and S-II and H-alpha) Extra-Narrowband filter to your astrophotography arsenal! Includes protective plastic case.