[filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!

["Austin Franklin" <darkroom@ix.netcom.com>]

Hi Toooooodd,

> > Ouch. Sigh. Dynamic range:
> > 1. The difference, in decibels, between the overload level and
> the minimum
> > acceptable signal level in a system or transducer.
> > <snip>
> > 5. The difference between the maximum acceptable signal level and the
> > minimum acceptable signal level.
> > (Modern Dictionary of Electronics, 6th ed.)
> >
> > Austin is, of course, right on this one.
>
> I don't claim to know DyR better than anyone else but I have followed the
> discussion for some time. So, I'm not sure why what you cite
> above supports
> Austin any better than Julian.
>
> My reading of Julian is that he is in full agreement/compliance
> with what is
> written above.

Possibly, but it depends on how it and the terms used are "interpreted".  I
don't recall who believes what means what, but the terms CAN be
ambiguous...and the ones cited certainly are.

> I believe he feels DyR is exactly: 5. The
> difference between
> the maximum acceptable signal level and the
> minimum acceptable signal level.
> (Modern Dictionary of Electronics, 6th ed.)

Again, what does "minimum acceptable signal level" mean?  Is that the
minimum measurable change in signal, or the lowest "voltage" the signal can
attain....  What does "maximum acceptable signal level" mean?  The largest
amplitude the signal can attain, or the highest voltage the signal can
attain?

> My reading of Austin is that he believes DyR is the The difference between
> the maximum acceptable signal level and the
> minimum acceptable signal level, divided by noise, (where noise is
> typically/frequently specified as 10.

It depends.  Using the definitions above, and using what I believe the terms
mean, I'll define the terms here...

Per definition 5 (because it's easier and more to the point):

"maximum acceptable signal level" means the largest amplitude.  It is
EXACTLY the same as the largest voltage the signal can attain, minus the
minimum voltage the signal can attain.

"minimum acceptable signal level" means the smallest amplitude that can be
measured.  Typically, this is noise.

If that is the definition of those two terms, than #5 is correct.  You can
extrapolate those definitions to #1 if you like, and therefore it's correct
too...

What happens is people don't understand the CONCEPT of dynamic range, and
therefore don't understand what the terms actually mean...and draw a
different understanding as to what dynamic range is.

> > Comment: this went back and forth interminably, and I think most of that
> > could have been avoided by actually quoting standard
> definitions of the term
> > and working from there.
>
> Just curious, would those standard definitions and terms BE what you quote
> above? If so, lets see if it makes a difference. I doubt it will...

That's the point, there ARE no standard definitions and terms...

Austin

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