Playing with stars and planets

(Location: Falling Waters State Park, Florida)

The photo is actually a "stack" of seven photos, taken over a three minute span, to capture the Earth's movement in relationship to the night sky.

The bright object(s) is the planet Jupiter. The others are surrounding stars. They are moving east to west (left to right in the photo). You'll notice a gap, where I stopped to adjust the shutter speed.

I took this photo(s) in response to a question I was asked about photographing the night sky and why the stars appeared to streak. It demonstrates a number of problems. Primarily, available light and how to deal with it. Apart from the dealing with the primary problem, it also demonstrates the technique of photographing star and planet "trails" as the object(s) move across the sky. If the central focus of the photo had been the North Star, instead of Jupiter, the streaks of light would go around in a circle.

Note the equal lengths of the first five objects in the sets. Exposure time for each was 20 seconds. For the last two, exposure was changed to 8 seconds and 4 seconds, respectively. With less exposure time the objects more closely assumed their circular shape. At 10 seconds each object would be represented with a single long streak of light. Optimal exposure time to capture the object without movement, using a still camera, is in the one to two second range. The problem would be how to capture that far away light in such a short time.

The solutions are varied, and involve changing film or digital chip speed, and a larger aperture setting (smaller number). This example was taken at F/5.8, ISO 100. A setting of F/2 ISO 400 would allow for more light to reach the chip (or film) faster and thus reduce the necessary shutter speed and eliminate the Earth's rotation.

Below is an example of stopping the night sky's motion. The arrow points to jupiter.

100mm F/2.8, ISO 800, 1 sec exposure

By the way, Jupiter is approaching it's closest position to Earth over the next few days and is an awesome sight in the camera lens or a good set of binoculars.

... and so it goes.