P3D Re: slide film or neg film?

[Brian Reynolds <reynolds@xxxxxxxxx>]

Michael Kersenbrock wrote:
> 
> One thing I forgot to ask about.  I recall your posting saying that digital
> cameras have only a 6-stop (bit) dynamic range.  It seems like that may 
> improve with time.  It certainly isn't inherent.

The limiting factor in many CCD based cameras is thermal noise.  In
order to get the full 8 bit range of CCD chips some form of cooling is
generally needed.  For astronomical cameras this varies from simple
heatsinks with fins, to thermoelectrical cooling (TEC), to liquid
cooling.  Consumer level astronomical cameras (with cooling) are
generally limited to 12 bits (although some do have 16bit DACs
(digital to analog converter)).

> The following link (company who's address looks to be less than a
> mile from where I am :-) shows a digital CCD camera with 18-bits of
> dynamic range!!!!!  Certainly not a $100 camera, but.... it can be
> done with effort (and money).  :-)
> 
> 	http://www.tateweb.com/news-pixel-sv330.htm
> 

This is a thermoelectrically cooled camera meant for spectrographic
use.  This camera does not take "normal" photographs.  Note that
although the theoretical limits for this camera exceed 18 bits of
dynamical range the DAC used only has 16 bits of resolution.

-- 
Brian Reynolds                  | "Dee Dee!  Don't touch that button!"
reynolds@xxxxxxxxx              | "Oooh!"
http://www.panix.com/~reynolds  |    -- Dexter and Dee Dee
NAR# 54438                      |       "Dexter's Laboratory"


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