Lucky stars
September 17, 2007 12:50 PM Subscribe
Using a $20,000 CCD camera and some new software, ground-based telescopes can now get images as good as the Hubble Telescope in many situations [some images ]. By taking many high-quality pictures quickly and taking the best parts of each, Lucky imaging compensates for atmospheric effects to produce lovely images. You can do it too, using free software and any webcam.
Too bad we used all that money for Hubble. We could have spent it wisely in Iraq.
posted by notreally at 1:29 PM on September 17, 2007 [1 favorite]
posted by notreally at 1:29 PM on September 17, 2007 [1 favorite]
If this interests you you might also be interested to hear about super-resolution.
posted by TheOnlyCoolTim at 1:34 PM on September 17, 2007
posted by TheOnlyCoolTim at 1:34 PM on September 17, 2007
Install it on Hubble and you'll have a super telescope x10. Don't worry I'll send my job application to NASA soon.
posted by romanb at 1:55 PM on September 17, 2007
posted by romanb at 1:55 PM on September 17, 2007
Metafilter: Collimating and guiding on the Airy disk even when seeing is bad.
(W-ever-TF that means...)
posted by twsf at 1:56 PM on September 17, 2007
(W-ever-TF that means...)
posted by twsf at 1:56 PM on September 17, 2007
twsf: Stars twinkle because their light must pass through pockets of Earth's atmosphere that vary in temperature and density, and its all very turbulent. On rough nights, a star appears to constantly shift position as its light is refracted this way and that. The process has been likened to watching a coin appear to dance at the bottom of a pool.
With dense stellar clusters, the twinkling can make thousands of tightly packed stars look like one giant blob of light. (Horrible resolution). That's what it means when the "seeing is bad". Some nights are worse than others depending upon the weather / upper atmosphere.
posted by spock at 2:07 PM on September 17, 2007 [1 favorite]
With dense stellar clusters, the twinkling can make thousands of tightly packed stars look like one giant blob of light. (Horrible resolution). That's what it means when the "seeing is bad". Some nights are worse than others depending upon the weather / upper atmosphere.
posted by spock at 2:07 PM on September 17, 2007 [1 favorite]
This is very cool and similar to how one takes an interior shot of Grand Central Station (which never closes) and yet show it as empty/devoid of people. You take a series of exposures on the SAME PIECE OF FILM with a camera on a tripod. You use a high shutter speed and small aperture so that very little light gets to the film. So if, for example, at f/32 you would need a 1 second exposure you instead take 500 exposures of 1/500th of a second. Each exposure is too short to register the moving people in the scene. The only light that consistently gets painted on the film (with each of the 500 exposures) is of the things which aren't moving (the building interior). When the image is developed, it is essentially a stack of 500 mini-exposures.
This "lucky imaging" does essentially the same thing, but the short exposures are stacked from those brief millisecond moments when the atmospheric seeing is clear. The complexity is in a camera that takes exposures that briefly AND your camera isn't on a "tripod" it is on a telescope that must be guiding along with the stars as the earth turns (which is not as simple as you might think, at high magnifications).
posted by spock at 2:19 PM on September 17, 2007 [2 favorites]
This "lucky imaging" does essentially the same thing, but the short exposures are stacked from those brief millisecond moments when the atmospheric seeing is clear. The complexity is in a camera that takes exposures that briefly AND your camera isn't on a "tripod" it is on a telescope that must be guiding along with the stars as the earth turns (which is not as simple as you might think, at high magnifications).
posted by spock at 2:19 PM on September 17, 2007 [2 favorites]
That was a great explanation, spock. I would have messed it up with the red-herring term "integration".
posted by DU at 5:03 PM on September 17, 2007
posted by DU at 5:03 PM on September 17, 2007
Nifty. Thanks, blah.
posted by weapons-grade pandemonium at 10:23 PM on September 17, 2007
posted by weapons-grade pandemonium at 10:23 PM on September 17, 2007
Damn your vulcan blood, spock, I'm a wonderchicken, not an astronomer!
(Which is to say, thanks for the explanation. That's pretty cool. As the price of processing power and data storage continues to drop, I look forward to all the other way clever stuff people are going to come up with.)
posted by stavrosthewonderchicken at 2:02 AM on September 18, 2007
(Which is to say, thanks for the explanation. That's pretty cool. As the price of processing power and data storage continues to drop, I look forward to all the other way clever stuff people are going to come up with.)
posted by stavrosthewonderchicken at 2:02 AM on September 18, 2007
This has been an issue in industrial espionage (at least) for fifteen years that I'm aware of. Pixel jitter and edge detection over many frames can increase the resolution of a composited image significantly enough to read text on a computer screen in the background of a video camera frame, for instance.
It's not as good as the absurd examples seen on TV and in movies ["Enhance that image! Zoom in and enhance it again! My God, the killer is wearing a silver ring with a small three-toed sloth engraved on it!"], but it's better than you might think.
posted by lothar at 9:19 AM on September 18, 2007
It's not as good as the absurd examples seen on TV and in movies ["Enhance that image! Zoom in and enhance it again! My God, the killer is wearing a silver ring with a small three-toed sloth engraved on it!"], but it's better than you might think.
posted by lothar at 9:19 AM on September 18, 2007
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posted by blahblahblah at 1:18 PM on September 17, 2007