In my earlier attempt to capture the Spaghetti Nebula I found that the 200mm camera lens wasn’t quite wide enough. And that a faster (lower focal ratio) lens would also be beneficial. So I put an 85mm f/1.8 Nikkor lens (stopped down to f/2.8) on the QSI camera and tried again last night. It didn’t work. The moon was full last night, and even with a 3nm H-alpha filter, there was enough sky illumination to almost completely overpower the Spaghetti. I’ll try it again when the Moon goes away, but I have to comment again on what this says about the dimness of the Spaghetti Nebula. Never before have I seen H-alpha nebulosity that was completely lost to Moonlight. In fact, my first few shots (when it was still fairly low in the sky) showed a significant gradient – greater background brightness in the areas closest to the horizon. That is, with such a long exposure, a 3nm H-alpha filter failed to suppress even fairly low levels of light pollution.
But while I was waiting for the Spaghetti Nebula to rise in the east (it didn’t get high enough to start shooting until about 1AM), I captured 8 frames of H-alpha covering the area around the stars Deneb and Sadr in the constellation Cygnus. This includes a large number of nebulae that I have photographed separately over the years: Starting in the upper left we have the North America Nebula, with the Pelican Nebula just to the right of it. Deneb is the bright star to the right of the top of the Pelican. Sadr is a little harder to pick out, as it is surrounded by bright nebulosity, but you might find the Butterfly Nebula down and to the right from Deneb. Sadr is just above the right end of the Butterfly. Above that and a little to the right is the Propeller Nebula, but there are several other interesting structures in this area that I’ve never seen or photographed before. Finally, the Crescent Nebula is in the lower right corner.
I’ll capture at least O-III frames and maybe also S-II frames to make this a full color image, but that will, again, have to wait for the Moon to go away.
Wide angle shots like this are very useful in trying to find new targets – and to better understand the “neighborhood” of targets already captured. And sometimes they make pretty pictures themselves! Processing such wide-angle images is a bit different from the more “close up” images I normally shoot. For example, many of the stars in this image are so tiny that they are indistinguishable from “hot pixels” – individual photo sites that produce a stronger signal than they should. Therefore, I couldn’t apply the filter that I normally use to eliminate hot pixels. But if you look at some of the images I’ve captured with super-wide-angle lenses, you might notice that individual stars in the dense parts of the Milky Way actually disappear as they merge into a “cloud” of brighter sky.