re: Astronomical Stereos

["Richard M. Koolish" <koolish@xxxxxxx> To: photo-3d@xxxxxxxxxxxxxxx]

Peter Abrahams writes:

>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.

There are at least two problems with using libration to get a stereo effect of the moon. The first is to get the same sun angle and the second is to get the two images when there is only libration in the horizontal direction. Paul Wing had a large collection of moon stereo pictures and was only too glad to point out the faults in most of them. 


>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 

I'm not sure I would call this false stereo. There is a real difference in the position of the comet with respect to the background stars. It doesn't make any difference if the comet moves or if the earth and the camera move. 

You can make a similar image of a solar eclipse by using the motion of the moon in front of the sun to provide the parallax. 


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