Dmax with b&w negatives

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

[originating from Leafscan Mailinglist, CC to IR-list]

A few weeks ago, I wrote on the Leafscan Mailinglist about my
assumption that b&w negatives could have a far higher Dmax than any
other film, in the context of scanning performance....that
assumption was countered by someone on the list back then....but
recently I found a (German, sorry) message in which my assumption is
confirmed, at least for one type of film (Agfa Ortho)....Dmax 3, if
not 4....trying to find out more right now (including other films
like this, therefore CC to IR-list....Kodak HIE didn't seem extreme 
in this department, scanned fine on an old Dmax 2.4 scanner (Microtek 
1850)....are only the ortho-type films problematic?).

xxxxxxxxxxxxxx
> Die Kontrastprobleme rühren vermutlich daher, dass das Negativ sehr
> steil ist (über 3 Dichten oder so), was bei Negativen normalerweise
> nicht vorkommt (wegen Gamma 0.6).

Jep. 

Der Agfa Ortho 25 hat nen Gamma > 2,5 und eine Dichte weit ueber 3, 
vermutlich auch jenseits der 4 (logD). Der Film ist zum Scannen 
ziemlich gemein, weil er kaum Mitteltoene hat, sondern die 
Towerte sich hauptsaechlich bei der maximalen Dichte oder
minimalen Dichte befinden. Deswegen wurde er frueher auch gerne
zur Reproduktion von Strichzeichnungen verwendet.
xxxxxxxxxxxxxxxxxxxxxxxxxxxx

--                 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand

<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]
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