----- Original Message -----
From: "Jan Steinman" <Jan@xxxxxxxxxxxxxx>
> >I think 36db is a wrong value, most agree slide has D-Range of roughly
4.0,
> >which is 10000:1 and 80db.
>
> Might you be confusing voltage (or current) ratio with power ratio? Light
intensity is always expressed as a power ratio.
>
Are you sure? seems that I have seen the video cam quote much more than 34db
SN ratio, they are better than slide?
> Each power increase by a factor of 10 yields another 10 decibels, or
another 1 point of dynamic range. Thus, a 10,000:1 power ratio is 40 db, or
a Drange of 4.0.
>
> If one were measuring potential or flow (voltage or current), one would
have 20 decibels for each 10x increase.
>
> Good drum scanners can see a Drange of 4.0, but in my experience, Velvia
doesn't stretch nearly that far. On my ColorGetter Falcon, 4"x5" RVP
(Velvia) seems to run from 0.16 to 3.4 or so.
>
Really? I just think Velvia provided the deepest color of all slides, if 3.4
is good enough then why people make the dmax 4.0 scanner? BTW, I found my
LS4000 (dmax 4.0) is much better than my LS2000 (dmax 3.6) in capture the
shadow details. You can curve up the shadow area to find out the details you
will not see in projection.
C.H.Ling
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