Re: News - Picture of Shuttle and ISS Silhouetted against Sun

On Mon, 2 Oct 2006 04:22:12 GMT, henry@xxxxxxxxxxxxx (Henry Spencer)
wrote:

Yes, even for light-gathering power, despite the smaller aperture, because the CCD needs a lot fewer photons
to form an image than the films the pros were using back then.

....On the other hand, there's two things about CCD that still makes
some astronomers prefer film:

1) The longer you expose a CCD in extreme low light, you get more
noise than you would with film. In addition, colors towards the red
end of the spectrum tend to get overly exaggerated as the exposure
progresses.

2) Cold-packing a CCD does absolutely nothing to improve the light
sensitivity, but freezing that film and then keeping the camera body
cold with an ice bag does improve the emulsion sensitivity by a
significant amount.


OM
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