M8
Lagoon Nebula in Sagittarius

10.1″ f/4.5, Mallincam DS432cTEC with Astronomik UHC filter
Exposure = 5-7.5 sec, Live Stacked frames = 20-20 (40 total), Gain = 50 of 250

M8 is a giant H II emission nebula in the Milky Way, about 4000 light years away. Despite lying low in my Bortle 8 skies it still appears quite spectacular. The dark rift separating the bright core of the nebula from the open cluster (NGC 6530) at bottom-left is visible in the eyepiece. Fainter extensions of the nebula reach well toward the left-side of this view and spill over the field of view. The bright star at top-right is 7-Sagittarii, a massive star visible to the naked eye (magnitude 5.37).

North at 11 o’clock, East at 8 o’clock

10.1″ f/4.5, Mallincam DS432cTEC
Exposure = 5-7.5 sec, Live Stacked frames = 20-45 (65 total), Gain = 20 of 250

The above view of M8, taken three weeks after the one at top, was done without a filter using similar exposure settings in order to compare against the Astronomik UHC filter. The gain needed to be a little higher for the filtered image because less light is transmitted. Note that there is a slight orientation difference too due to the images being taken at different times in the evening.

The image with the filter (at top) has a little more detail in the dimmer extended areas of the nebula, for example towards the bright star 7-Sagittarii. The image without the filter (above) appears to have greater contrast in the darker areas, which enables viewing more details in the bright regions near the core for example. Also, the image without the filter provided a more pleasing vibrant rosy-red colour to the nebula whereas the filter tended to colour the nebula brown (colour in the image was subsequently adjusted in post-processing but it still has more brown than red).

North at 2 o’clock, East at 11 o’clock