I started my astrophotography about a year ago with Canon 1100D and 70-200mm f/4 lens. Now Ive upgraded to full frame DSLR (6D) and also bought second-hand Sigma 120-300mm f/2.8 for wider aperture and more focal lenght. First light for this lens was small comet that moves along the Milky way, Jaques C/2014 E2. I dont have my own tracking mount yet, however my friend does have astrotrac and often we shoot together so I get a chance to use it.
Finding Jaques was quite hard, at the time I started and finaly found it 30 minutes later after around 20 test shots around the constellation of Cassiopeia I stumbled on a problem. The comet was too hing on the sky to get it in the center of the frame for better sharpness! I usualy get my subjects in the center of the frame for less vignette and better sharpness because I need to crop the images anyways so composition can be adjusted in post-processing.
Tracking was quite successful, I managed to get 30s with no trailing at 300mm, however the time had passed and the clouds moved in, luckily there was some gaps in the clouds and I maged to get 10 cloud free shots.
I aligned the images in Hugin, clicking control points in the comets core. After saving the exposure layers I stacked them using EnfuseGUI and of course ended up with sharp comet but star trails.
I did second stack using same method but for stars, then removed the comet in Photoshop CS2 and merged the images together. You could do this with DeepSkyStacker or any other stacking program dedicated for astrophotography. However I use free softwares and Hugin / EnfuseGUI does fantastic job for alignment and also it keeps the colors unlike DeepSkyStacker.
The downside is that these programs require more manual work that DSS because they are less automated, however when you get a hang of it its really simple and does fantastic job for colors and alignment.
This is what I ended up with:
