This is Comet Lovejoy (C/2014 Q2) as shot on January 11, 2015, from near Silver City, New Mexico, using a 135mm telephoto lens for a field of 15 by 10 degrees. The comet was in Taurus. The image records the faint blue ion tail stretching back for nearly half the field, about 5 to 6 degrees. This is a stack of 24 x 1 minute exposures at f/2 and with the Canon 5D Mk!II at ISO 1600. Tracked but not guided with the Sky-Watcher Star Adventurer.
The Amazing Sky 