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Robert Atkinson wrote:

> Likewise there is no point in attaching a high resolution
>analogue to digital converter to a limited dynamic range sensor. There
>are a number of cooled CCD cameras on the market that claim 16 bit
>resolution when the well depth of the CCD is less than 30,000 electrons.
>How do you measure 1/2 an electron?

You can still get 16-bit depth by binning - so long as the serial
register has sufficient capacity.  Often in quantitative work
it's worth sacrificing some spatial resolution to get better
numbers.  If you are measuring cytosolic Ca or mitochondrial
membrane potential you often have no need of 1280 * 1024 (or
whatever) pixel resolution.

In confocal rater than CCD work  find it's essential to use 12 bit
when doing spectra on my Leica TCS SP2 - the difference between
the highs and lows of the spectrum means that 8 bit isn't enough.
Of course, as George pointed out there aren't going to be that
many photons in one scan so long integration is the key - plan
to collect the spectrum while you're out to lunch!

                                                Guy


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