Alin,
I provided conversion factor in my email (re: Pos vs
neg grain(RMS conversion).
You may have missed it. If you wish, I'll supply URL.
Jack
"rule-of thumb, multiply neg RMS by 2.5 to compare to
pos RMS"
--- Alin Flaider <[EMAIL PROTECTED]> wrote:
>
> Jack,
>
> First I want to correct myself: I meant Kodak RG25
> not 50 (I don't
> even know if there was such a beast as RG50).
> Second I am not aware there may be different RMS
> measurements or
> interpretations for negative and slide film.
> According to Agfa
> technical documents they use the same technique
> for both negative
> and slide. Maybe you are referring to PGI (Print
> Grain Index) Kodak
> introduced to scale emulsion grain to printed
> paper grain? They do
> claim that negative film grain cannot be directly
> compared to
> positive film and a translation is in order (via a
> reference
> printing system / reference paper). Whether this
> supports a real
> fact or Kodak just wanted to avoid a direct
> comparison to its green
> rival is anybody's choice...
>
> Servus, Alin
>
> Jack wrote:
> JD> Alin,
> JD> Useful and much appreciated information. Thanks!
> JD> Pos and neg RMS factors relate to two different
> JD> scales. The actual conversion factor escapes me
> at the
> JD> moment. If I should locate it, I'll put up on
> list.
> JD> This isn't to say that the total of all other
> JD> information you furnished isn't exactly right.
> Just
> JD> wanted to make the minor point.
>
>
>
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