I made it out to my dark sky site again on Mother’s Day, 2017. Mom’s house was on the way there, so I managed to visit with her before my imaging session, which worked out pretty well.
Comet Johnson was my only target on this evening. I used my Canon T3 with no LP filter at ISO 3200 with 3 minute sub-images. That was about max for this particular night in that area of the sky. A few high clouds interrupted me after about 8 shots, but I was able to continue shooting after they moved on.
I was hoping to catch a glimpse of the ion tail with a single exposure, but no luck in that department. The LP dome to my northeast that the comet was embedded in was the limiting factor here. Maybe the LP filter would have let me use longer exposures and I might have been able to detect the ion tail like that.
The 3 minute subs let me track the stars with only minimal pseudo-nucleus smearing, but anything longer and I would have had to track the comet. That makes it harder to do star-freeze processing if the stars are trailed, however. I either have to fix the trailing in post-processing or shoot a set of star-tracked sub-images.
Here is another go at Comet Johnson from the city with my older Canon XS camera. The light pollution was at a minimum with above average transparency and low humidity levels this night. Still, being limited by the LP in exposure time made getting the ultra-dim ion tail and the full extent of the dust tail almost impossible.
I wanted to go to my dark sky location and shoot this, but the conditions were so iffy that I stayed in town. Clouds plagued the area all afternoon and it was just before twilight ended that the skies became clear enough to image. So, I probably could have done good away from the city, but the risk of it not clearing and wasting my time waiting for the clouds to leave was just too high.
Here is another Comet Johnson image from my Bortle red zone location. I used my older, modified Canon XS camera and ISO 200. I had read somewhere that ISO 200 on the XS series was close to unity gain and I wanted to see for myself how sensitive it was shooting in the red zone LP at this setting.
I went with 5 minute subs with tracking on the comet enabled and got 11 before moonrise. I probably could have gone 8 minutes in these conditions with ISO 200 to hit mid-histogram, but I stuck with 5 minutes since the histogram hump was still well away from the left hand side. Plus, it was about 70 degrees this night and the camera showed lots of hot pixels even using ISO 200. It would have just gotten worse with longer subs.
The comet was at a low altitude starting out, so the LP and atmospheric extinction hindered me getting the really dim ion tail and the more subtle parts of the dust tail. With moonrise coming so soon, I couldn’t wait until it got any higher, unfortunately.
It is not a great image but not too bad, either. At least I tested the XS and verified what it can do. It is more suited for shooting nebula, since it is a modified camera, but I haven’t used it in so long that I forgot how it performed on comets.