The Biggest Physics Stories of 2024
17 hours ago
2011-07-03
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4 comments:
Hi there, Austin
That's a great photo, and one that demonstrates your point very neatly. The original (on Flickr) also neatly demonstrates the relative motion of the Earth and the sky: the exposure is just long enough for the stars to appear as very short trails.
As a point of interest, the photo would not be possible in Britain: we're too far north for the more spectacular half of the Milky Way ever to appear in our sky, and also a fairly high proportion of the country now has too much light pollution to be able to see much in the night sky at all :-(
Take care
Mark
In point of fact, that was from the top oh Haleakala in Maui - 10k feet up (that's, what, 3km?). I think it's possible to get something low over thesouthern horizon from the socal deserts, but I haven't tried yet.
And yeah,the trace paths of the stsrs are just starting to show there at 60 seconds. I want to get a better camera and/or lens where I can take a wider shot with a shorter duration and still get the same visibility; the 17/2.8 becomes a 26/2.8 on my camera, and it just wasn't wide enough.
Hi there, Austin
For some reason, I thought the photo was taken by the sea: the hazy grey area between the black silhouettes and the sky looked rather like the sea, with a low wall in front as one might find at the top of a beach. It's only on looking more closely that I've seen the telescope domes on the right-hand side of the picture.
Another tactic for avoiding star trails would be to do what astronomers do with telescopes, and put your camera on a motor-driven mount so that it follows the angular motion of the sky. I've no idea whether anything like that is commercially available, though - most people taking their astrophotography that seriously will be using a telescope in the first place.
Take care
Mark
It's called an equatorial mount, and they're pretty commonly available though expensive. Even using telescopes, you have to use one else your telescope will lose sight of your target after a few seconds. The problem with a mount is not only that it has to be calibrated for your location but that anything on the ground then becomes blurred by motion lines; if you're just doing star shots, that's obviously not an issue.
That grey area is actually cloud. At 10k feet, you're above most of the cloud level for the island.
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