Colour Magic 2-inch Duo-band C1 (Hα+OIII)

 The Colour Magic C1 2-inch Duo-band filter is designed for advanced deep-sky astrophotographers who are shooting emission nebulae, like the Orion Nebula (M42), Lagoon Nebula (M8), or the Ring Nebula (M57). 

Unlike most filters, which record a wide swath of the visible-light spectrum, this filter only records the specific, brightest colors of glowing hydrogen gas (the “H-α” or Hydrogen-alpha) in your camera’s red channel, and oxygen gas (the “O-III” or Oxygen-III) in the camera’s green channel. Because glowing nebulae often radiate light in these two colors, this filter is very good at increasing the contrast for nebula images—emphasizing the nebula and darkening the background and stars to a great extent. 

In the hands of an experienced astrophotographer, the Colour Magic C1 is capable of fantastic images on its own, but when paired with the Colour Magic C2 filter (which captures light from O-III and Sulphur II), the combined C1 + C2 filter set can produce color images in the so-called “SHO” or Hubble Palette. (You will need special image post-processing techniques to accomplish this, so Hubble/SHO images aren’t well-suited to beginners.) 

** For those of you already familiar with dual-narrowband filters, the Colour Magic C1 is very much like the well-known Optolong L-eXtreme and Askar’s Colour Magic D1 filters. All three filters (C1, D1, and L-eXtreme) are dual narrowband H-alpha + O-III. But the C1 filters have a wider (for a narrowband filter) bandpass than the other two filters, so they’re a much better choice for faster (f/2.8) optics. The C1 also passes a little more light through than the the D1 or L-eXtreme, so they will be a little easier to work with when  you're using the built-in guide cameras that ride along with some of the latest ZWO astro-cameras. If you need the tighter 7nm bandpass, stick with the L-eXtreme or D1—but otherwise, the C1 may be easier to work with overall and they’re less expensive!  They’re a compelling choice for folks just starting to work with narrowband images with color cameras.

Specifications

IC 1848 Soul Nebula(HOO)  |  ASKAR 103APO+0.6x Full-frame Reducer+ASI 2600MC Pro  |  Colour Magic C1 Duo-band Filter (Hα+OIII)