The Lagoon Nebula

Here is a reprocessing effort on some data collected in 2006. H alpha nebulae have always been a difficult target as I use an unmodified Canon DSLR which doesn't have the best sensitivity at those wavelengths. In order to make the nebula visible, extreme stretches are generally needed. These stretches usually result in bloated and excessive numbers of stars that tend to obscure the nebula as shown in the image below. The picture that shows up when your mouse is not over the image is a 15 minute exposure at ISO 800. It is a stack of three, five minute shots. Calibration and stacking was done in Deep Sky Stacker . There was some collimation and tracking issues that have not been corrected. The stacked image was stretched and the red channel was given a slightly (?) excessive midlevel stretch to try to emphasize the nebula over the stars.

Click on the image to see the reprocessed version. In this case the calibrated and stacked image was contrast enhanced using digital development processing in Images Plus three times producing three images with different amounts of stretch applied to each. These images were then combined using a layered, masked stretch (LMS processing) and the bloated stars were reduced in size using a single pass of star shrink processing . The background was equalized  and a duplicate layer was produced and given an extreme contrast enhancement using the clarify function in Paint Shop Pro. The two layers were recombined using a mask made from the luminance channel to blend them together based on brigntness. Star colour was enhanced and masked noise reduction was applied. Finally the result was sharpened using Focus Magic and the unsharp mask function in Paint Shop Pro.

Click on the image again to see the original. The images are at slightly different scales as the original was cropped to remove amplifier glow while the reprocessed version has had it removed.

Object The Lagoon Nebula (M8) RA 18:03:00 Dec +24:20:00
Exposure 15 minutes (3 X 5 minutes)
ISO 800
Camera Canon 350D DSLR
Optics Prime focus of a 200mm Meade Schmidt-Newtonian

St. Croix, Nova Scotia

Processing See above