One of the fundamental issues in astrophotography is the general lack of light. To combat this, many serious astrophotographers turn toward equatorial mounts to allow them to get more light, but this can create difficulties if you have a foreground subject as well. This helpful tutorial will show you how to composite a foreground shot with a tracked night sky shot.
Coming to you from Milky Way Mike, this great video tutorial will show you how to composite a foreground scene with a tracked night sky shot. Because the night sky gives off so little night, in addition to using wide aperture lenses, many serious astrophotographers turn to equatorial mounts. These are special motorized camera mounts that synchronize to the rotation of the Earth to counteract star trails caused during long exposures. The problem then is that by rotating the camera to follow the night sky, the foreground then rotates relative to the plane of the camera, thereby blurring it. Photographers solve this by taking a separate exposure, but compositing the two can be a bit tricky since the camera moves during the sky exposure. Check out the video above for the full rundown of the technique.