I captured a few images with the Canon T4i (unmodified) with the 70-300mm zoom at 200mm and fully open at f/5.0. I was using the camera tripod so limited the exposure to 2seconds at ISO1600. Of the 17 images, only 4 were usable. The others exhibited serious camera shake even though i was using mirror lockup and a 2sec timer. I manually aligned and stacked (blended) the best 4 in Photoshop and then stretched them in PixInsight. I could not get the tail to show up very well, although with a little imagination the comet does appear teardrop shaped.
Camera: Canon T4i (unmodified)
Lens: 70-300mm zoom at 200mm, f/5.0
Exposures: 4x2sec @ ISO1600
Mount: Camera Triod
Aligned and Stacked: Photoshop