Who is Mark Nelson and what is his method of making digital negatives?
>From: Sandy King
>Reply-To: alt-photo-process-l@sask.usask.ca
>To: alt-photo-process-l@sask.usask.ca
>Subject: Re: density range
>Date: Sun, 31 Aug 2003 15:05:32 -0400
>
>Jacques,
>
>When I first started making digital negatives I just got the image
>to
>what I wanted it to look like on screen, applied one of the curves
>from Dan Burkholder's book CD, and printed it. Luckily the negative
>turned out to have a density range about right for my process, as I
>was able to verify by actually printing it. Since then I have
>developed another curve for my processes based on Mark Nelson's
>method and negatives made with this curve print almost perfectly. I
>also measure the density range of my negatives with a UV reading
>densitometer and can verify that they have a log density range of
>about 1.8.
>
>Log value is a sensitometric term that can be translated into stops.
>A log value of 0.30 equals one stop, log 0.15 equals 1/2 stop. Pt/Pd
>as a process has a log exposure scale of about 1.65 - 1.80, which
>could also be stated to be a range of about 5.5 to 6.0. So to print
>all the tones of a negative you need to have a negative density
>range
>of about 1.65 to 1.80 to match the ES of Pt/Pd.
>
>Sandy
>
>
>
>>
>>Sandy,
>>
>>in your last post you say (quote) Both processes require negatives
>>of the same density range (about log 1.65-75) and the final images
>>of the two processes are for all practical purposes identical in
>>terms of color and tonal range.
>>
>>I am about to start pt/pd printing, but I am still struggling on
>>the
>>measurement of density ranges for (digital) negatives. people on
>>the
>>list come up with log. ......, but how can I find out (or change)
>>what the log of a specific (digital) negative is. I have been
>>reading through Dan Burkholder's book and also John Barnier's
>>Coming
>>into Focus, where actually on page 233 several curves are given in
>>D-max, but somehow there is a gap in my brain translating these
>>figures into common sense (i.e. a correct curve for e.g. pt/pd
>>printing).
>>
>>Maybe you can just cast the right light on my missing link.
>>
>>Thank you.
>>
>>
>>Jacques Verschuren ABIPP ARPS QEP
>>Fotografie Jacques Verschuren
>>Ronduitsestraat 2
>>5443 BC Haps (N-Br.)
>>The Netherlands
>>T. + 31 485 331210
>>F. + 31 485 318569
>>www.jacquesverschuren.nl
>>
>>-----------------------------------------------------------------------------------------------------------------
>>12¸ years of photography in
>>www.jacquesverschuren.nl/milestone.htm