Giving nebulae a BOOST

AMONG THE MOST PHOTOGRAPHED OBJECTS in the night sky are emission nebulae. These expansive fields of eye-catching red and magenta nebulosity, with occasional flourishes of orange, make for beautiful celestial portraits. However, getting those rich colours isn’t always easy, particularly if you live and shoot from light-polluted locations. While one-shot colour cameras like DSLRs or mirrorless cameras can capture the entire spectrum of visible light, often their utility is compromised by light pollution and skyglow.

One way around this limitation is to image through narrowband or other specialised filters to increase the contrast in the images. Ultra High Contrast (UHC) filters sold by various manufacturers are a type of combined narrow-bandpass filter. They work by passing specific wavelengths of light, commonly found in nebulae, while blocking unwanted wavelengths from most sources of skyglow. Oceanside Photo and Telescope’s new Triad filter works in a similar fashion.

Individual narrowband filters allow only a fraction of the visible spectrum to be seen by the camera. Most commonly used is the hydrogen-alpha (Hα) filter that blocks all wavelengths except those surrounding ionised hydrogen emitting light at 656.3 nanometres. Since