Archived posting to the Leica Users Group, 2003/06/30
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Ansel Adams (The Negative) and Phil Davis (Beyond The Zone System) have pretty well documented the "how" and "why" of densitometer useage better than I will attempt. But in brief, if you really want to maximize your control over print tonality and contrast, sooner or later you're going to find one very handy. One of the most basic uses is to determine the effective film speed for a given film/chemistry combo. The most direct approach is to expose a series of frames of film at Zone I, at manufacturer's recommended film speed, and a series of others at above and below it. Process per manufacturer's recommendation and locate the frame which corresponds to X density units above filmbase+fog, and you've found your effective film speed for this particular film/chemistry combo. Exactly what "X" is seems to be subject to some debate, but Adams suggested 0.10 density units over filmbase+fog. Maybe someone could chime in with suggestions on whether this figure needs to be revised when working with newer emulsions like Acros. Once we've established the effective film speed, we can go on to determine proper N, N- and N+ developing times. The problem of devoutly following the Zone System is that you'll probably never take another photo again, save for Zone I and Zone VIII test exposures, because in theory, you should run the tests for EVERY meter and shutter that you own. And I don't care how good you are, getting a precise 0.10 Zone I test exposure repeatedly is really tough, particularly if you're using mechanical shutters. For this reason, I think David Vestal nailed it in a column about his relaxed, "sort of Zone System" (Vestal At Large, Photo Techniques, issue ??) Heiland (of Wetzlar!) has a unit that looks especially handy for the b&w photographer: It's a simple digital-readout model that works in both transmission (for examining negatives) and reflection (good for evaluating prints) modes. But many of the used densitometers on eBay should work as well. Jeff >Date: Mon, 30 Jun 2003 12:33:04 +1000 >From: Alastair Firkin <firkin@ncable.net.au> >Subject: [Leica] Digital has WON? Yes, but how about a >lesson on Densitiometers > >Speaking of the darkroom: any one like to tell me about >densitometers __________________________________ Do you Yahoo!? SBC Yahoo! DSL - Now only $29.95 per month! http://sbc.yahoo.com - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html