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Those of you interested in unusual photographic methods might be interested in the following article on nighttime photography.
The November, 2005 issue of Optics and Photonics News contains an article on nighttime photography by Dr. Joseph A. Shaw, Associate professor of Electrical and Computer Engineering at Montana State University. Illustrating his thesis with several nighttime photographs (one included here) he shows that the colors of the night sky and of the landscape it illuminates are the same as those found in the daytime. In other words it is possible to take the same pictures at night, without flash photography, showing the same colors, as would be taken in the daytime. This is a result most of us would not expect since what we see at night appears mostly black and white.
Shaw observes that the primary source of light, day or night, is the sun, and the nighttime sky is illuminated mostly by sunlight reflected from the moon. The nighttime sky appears black and white to us because of the physiology of the human eye under dim light conditions. But cameras do not have this limitation and can produce accurate color where we see only black and white. This is especially true of digital cameras, which produce pictures under an exceptionally broad range of illuminations. Film doesn’t do quite as well. It is less sensitive at long exposure times (called reciprocity failure). Of course if we want to take photographs using moonlight, and have them appear like daylight photographs, we have to use very long exposure times. Shaw calculates that exposures under full moon conditions have to be about 500,000 times longer than in daylight. A photograph made at 1/1000 second at f/5.6 in daylight would require an exposure of about 8 minutes at f/5.6 at night. Stars appear as streaks in these pictures due to the rotation of the earth during the exposure. If you point your camera toward the North Star you will find that these streaks form circles around it.
Exposure time varies with the phase of the moon and the location of the moon in the sky. Shaw did not discuss photographs taken when there was no moon. Starlight alone will be hundreds of times darker than moonlight and may not have the same color spectrum, so that pictures taken without the moon might show different coloring. If you want to take nighttime pictures try to find locations where there are no city lights, because they can overpower the natural light, a problem astronomers contend with on a regular basis.
So go try this and post some results. Dr. Shaw says he will answer any questions you might have, and I’d like to know if you found this posting of value.
Photo Dad
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Originally Posted by Photo Dad
Re: Mt. Diablo?
Apparently, Photography By Starlight IS Possible!
Astrophotography Films
