A Bresser Messier AR 102xs f/4.5 ED refractor was mounted on an HEQ5 GOTO mount. An SVBONY SV305M Pro was fitted with an Optalong L-eNhance narrowband filter. This filter has two bandpass zones with high transmission. The bandpass at the longer wavelengths in the red, includes H-alpha but not SII. The other bandpass includes the peaks of H-beta and OIII.
Transmission curve of the Optalong L-eNhance narrowband filter
The spectral lines of sodium and mercury, two major components of artificial light glow, comprising light pollution, are filtered out as there is zero transmission at their wavelengths. This filter passes about 95% of the light from H-alpha, H-beta and OIII nebulosity, cutting out most of the spectrum that could lighten the background of an image.
This experiment was to capture a monochrome image in the wavelengths of H-alpha, H-beta and OIII, using an SVBONY SB305M Pro monochrome camera.
AstroDMx Capture for Windows was used to capture 60 x 60s exposures with matching dark-frames and 50 x bias frames.
Screenshot of AstroDMx Capture for Windows, capturing data on the Bubble Nebula in Cassiopeia
The images were stacked in Affinity Photo and also in Deep Sky Stacker. The results from these two work flows were further processed in Affinity Photo, The Gimp 2.10, Fitswork and Neat Image.
Final image of the Bubble Nebula NGC 7635
The Optalong L-eNhance filter is primarily intended for use with an OSC (one shot colour) camera to enable the production of images with palettes comprising H-alpha, H-beta and OIII colours. This will be done in the future, but this filter acquitted itself well in producing a monochrome image, which could, in another narrowband scheme using H-alpha, OIII and SII, be used as luminance data.
