An iTelescope Article by Dr. John Ebersole
If you enjoy photographing nebulae, I hope you will try narrowband imaging. The results are worth the small amount of extra effort.
For many of us, our first view of a narrowband image was the 1995 release of the “Pillars of Creation” from the Hubble Space Telescope (HST) (Fig. 1). It was significantly different from the typical views of red emission nebulae, when RGB filters are used. Not only were the colors different, but there was remarkable color contrast and a 3-D effect unusual for traditional color images. This image was taken with emission line filters for ionized Hydrogen alpha (Ha), Sulfur II (SII), and Oxygen III (OIII). These three grayscale images were combined into an RGB color image using the now classic, wavelength-ordered (longest to shortest), HST palette, wherein SII is portrayed in red, Ha in green, and OIII in blue.