Re: [APML] Dynamic Range of CCD

[Aplanatic@aol.com]

Hi Loke,

I'm enjoying your tri-color Schmidt photography a lot.  Great stuff.

> The KAF3200 datasheet states that the dynamic range is 72-77dB or 3981
>  - 7079 and not 2300. Are you using a more stringent definition? Whatever
>  the definition of a minimum detectable signal, I would think that this
>  would be a clearly defined specification for CCD detectors. I would
>  presume Kodak would have taken this into account. 

Good point.  I had also considered using, as the noise floor for the dynamic 
range, the readout noise of the ST-10E, which is 11 electons RMS.  This would 
yield a dynamic range of 77,000/11 = 7000 and would agree with Kodak's 
specification.  This, by the way, is the "standard" method of calculating the 
dynamic range in electronics or at least one of the main ones.

But after reading Jerry's post a few times, I came to the conclusion that 
minimum detectable signal is closer to what he considers dynamic range for 
film.  At least I think so.  If the signal is equal to the noise then you 
basically can't claim to have detected it.  So, yes, I'm using a more 
stringent requirement.

Using a S/N of 3 as the minimum detectable signal is very standard.  It means 
that for a single pixel or the sum of a number of pixels, you can claim with 
reasonable certainty (99.5%) that the observed brightness is not due to 
random noise.  Of course, you might want to apply an even more stringent 
criteria if you were claiming to have discovered an asteroid from a single 
image.  <g> 

In the end, 10 or 11 stops of dyanmic range for daylight photography is quite 
reasonable, as a comparison to film's 7 stops.  But it still depends on your 
definition, or Kodak's.

Dave Rowe


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