Re: [APML] Fw: images

[Chuck Vaughn <aa6g@aa6g.org>]

Radu,

I apologize that I'm having some difficulty understanding what you're 
trying to tell me. I think you're saying the same thing that Rick was 
implying and that is log data has a lower S/N than the same data in 
linear format. Of course this is not true.

The whole thing about CCDs (aside from QE) is that they do have much 
better S/N than film. This is the reason you're seeing a whole new 
level of detail emerge in familiar objects. You could produce the same 
results with film if you could stack, oh let's say, 100 negatives.

You put higher QE together with better S/N of the recording media and 
add in dark skies (also higher S/N) plus filtering techniques (even 
more S/N) and you get results like Tony presented.

Chuck

------------------------

>
> Chuck,
>
> There's a qualifier to the above argument: film's response to light is
> non-linear; if you convert your output (scanned) levels to light, your
> dynamic range extends. A more faithful comparison would be between
> digitised film and gamma-corrected ccd data. i think you will find that
> even though the ccd has significantly better SNR, the diference is not
> as large as it would seem at first sight.
>
> radu

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