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* Cesco * ha scritto:
Siamo sicuri che sia quella la foto? Perchè mi sembrava di averla gia vista in giro tempo fa...
04/10/2009, 12:17
04/10/2009, 13:26
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si tratta di saturazione del ccd della videocamera o telefonino. il sole con la sua intensa luminosità satura il sensore che spegne le celle troppo illuminate facendole risultare nere. inoltre vi è un chiaro blooming che appare come fascio di luce verticale. altro difetto dei sensori fotografici che travasano parte della loro carica elettrica in eccesso dalle aree luminose alle celle adiacenti, di solito verso una direzione o entrambe.
ecco un altro esempio:
http://www.flickr.com/photos/11282735@N00/28932104
C'è anche chi ne ha fatto una forma...d'arte!!! http://www.harlanerskine.com/blog/2008_ ... chive.html
tratto da: http://mintaka.sdsu.edu/GF/observing/artifacts.html
blooming:What you see here is leakage along the columns of the CCD, caused by the overexposed solar image. I'd have expected this streak to appear red, but maybe the green hue is due to a color-balance shift of the kind discussed above: notice that the clouds around the Sun appear yellow, rather than the reddish orange you'd expect. In any case, this is a camera artifact, not an atmospheric phenomenon.
What's happening here is that the Sun's bright image produces vastly more photoelectrons than the maximum capacity of the little "electron wells" in the chip that hold and transport the charges forming the image. It's sort of like those plastic ice-cube trays that have little grooves between the compartments, so that you can run water into one, and it will progressively flood the others. Here, it's electrons instead of water, but the overflowing process is analogous: excess charges flood the column, producing a bright artifact in the image, as if it had been exposed to a vertical strip of light in the image plane.
sovraesposizione estrema:The black stripe at the bottom is a different side-effect of extreme overexposure. Apparently the intense illumination at the solar image has made the column "leaky", so that it failed to shift out all the image charge from the more distant rows, which have to be passed along the electronic "bucket brigade" more times than those at the top. So electrons that should have contributed to the brightness at the bottom of the affected columns failed to appear in the readout, and this area came out black!
04/10/2009, 15:16
* Cesco * ha scritto:
Siamo sicuri che sia quella la foto? Perchè mi sembrava di averla gia vista in giro tempo fa...
04/10/2009, 15:26
04/10/2009, 17:59
05/10/2009, 08:48