In a piggyback shot, the camera is mounted on a moving platform, usually a telescope with a motor drive, which cancels out the rotation of the earth. A properly aligned telescope can provide the piggyback photographer with breathtaking images of the night sky. However, when those shots include foreground objects such as buildings or trees, those foreground objects invariably appear blurred. This is because the telescope's motion is following the sky, setting the terrestrial objects into apparent motion over the course of an extended exposure.

The above photo is an animation of 3 two minute shots taken over a period of about 7 minutes. Notice how the sky is apparently motionless as the animation proceeds but the trees appear to rise and shift to the left (camera pointed southwest at milky way in Sagittarius). The longer the piggyback exposure, the more blurred the foreground objects will appear. This is not an error on the photographer's part, but a fact of life in piggyback photography. Many piggyback photographers will shoot a stationary shot of their foreground composition to later edit into their piggyback shot, giving the best of both worlds.