I was using a 28-105 mm zoom lens, so after centering the comet, I took images at maximum zoom:
The comet is just left of center and Cassiopeia's center star is at the right.
Here is an un-cropped wide-field image. Depending on how well this web media preserves the image size and quality, you may be able to click into the image and see the comet and the Andromeda galaxy.
When you think about it, the above image shows Earth, an object from our solar system, our galaxy, and a distant galaxy.
Using the telephoto lens, you can also detect the comet's movement against the background stars. This animation joins three images taken between 9:40 and 11:05 pm:
The first two frames were taken at focal length 70 mm, and the last at 105 mm. I wasn't planning to capture an animation, so I failed to keep consistent camera settings throughout my session, but you can tell the comet's motion is not due to my inconsistency.
Update: I've added a map showing where to look on Aug 25: