Astronomical Stereos

[telscope@xxxxxxxxxx (Peter Abrahams) To: photo-3d@xxxxxxxxxxxxxxx]

Stereo photographs of the moon are true stereos. (Note: flame bait.) The effect of a baseline thousands of miles long is provided by the moon's libration. The moon does not present exactly the same 'face' to the earth over the months. It wobbles or swivels slightly on its axis, a very complicated motion whose greatest extent is side to side. The moon was a popular subject for stereophotography in the Nineteenth century. The first known lunar stereo was taken by Warren de la Rue in England in 1858. The solar eclipse of August, 1869, was photographed stereoscopically, but likely was a flat pair. Keystone produced about 30 astronomical views, most are scarce, but 8 are from its common larger sets. The moon was the only true stereo, photos of Mars, Saturn, Uranus, and meteors were quite flat. The view of the sun is also flat, but the potential for some stereo effect is there, since the sun rotates. However, the lack of features on its surface, other than a few sunspots, makes it hard to get a stereo effect. A very beautiful Keystone stereo (#600) is of Moorhouse's comet (of 1907, I believe.) This has a dramatic false stereo effect, provided by the motion of the comet across the sky in the day or days between exposures. There will be a wonderful opportunity for stereo photographers to try their luck at this type of picture in about a year, when comet Hale-Bopp is at its brightest. It is predicted to be very bright, and an easy object for a telephoto lens. See Stereo World, 11/12 1985, for an article on how to photograph Halley's Comet. It is very unlikely that Hale-Bopp will be as dim an object as Halley was on its last go-round. --On libration: a stereo photographer could get a true stereo portrait by asking the subject to turn slightly left or right. However, the background would not be shifted. Would the photo look unusual or less stereoscopic? Addenda?--Assessments???--Replies???
telscope@xxxxxxxxxx (Peter Abrahams)
the history of the telescope,
the prism binocular, and the microscope


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