[at-l] Idea for WOW pic on AT

[shane@xxxxxxxxxxxxxxxxxxxxxx (Shane Steinkamp)]

> Film records whatever light shines on it (within the
> limits of it's latitude) for as long as it shines on it.
> One of the limitations of digital is that the sensors (at
> least those used in consumer cameras) don't "remember"
> light over long periods of time so exposure isn't
> cumulative like it is with film. Many of the photos on
> AOPD are digital (all of them from the Hubble telescope
> and other space based images) but I think they
> must be compiling repeated exposures or computer enhancing
> them. Any astronomers out there who know how they do that
> digitally?

The sensors are actually sampled repeatedly, and the image data accumulated
digitally.  The sensors can't 'remember' anything at all - only report.  A
digital sensor (CMOS or CCD) can be left 'on' and it's information
accumulated forever - an infinite exposure.  The problem with this process
with digital technology is the power consumption.  Long exposures eat
batteries...  Most digital cameras keep you under ten seconds.  The higher
end cameras go to fifteen seconds - and the really good ones give you thirty
seconds.  My Sony MVC-CD300 only give me eight...

Shane