Hello all!
First off let me apologize for posting this question. I know this subject has been beaten to death, but I can't seem to get a foothold. Also, please excuse me for posting in a large format forum when I shoot 35mm & 6x6.
I am having trouble figuring out negative densities. I am not looking for a magic bullet, however I am trying to reach a level of understanding where I can remove unknown variables, by making them known and controllable, that way I can focus on other areas that I need too, such as composition and the likes. (I am a left brain personal so I lean towards the technical aspects of a problem first)
Before I pose questions let me explain what I do understand about the Zone System and negative densities.
I understand the zone system to be a technique/method to expose, develop and print photographs. It encompasses various variables such as development temperature and time to produce predictable results using consistent techniques and equipment. (How’s that for generalization?)
For a simplistic example: I expose an 18% gray card at the settings my meter advises me to and I will get a Zone V density in the negative when I develop the film under my personal normal development procedures.
Similarly I will get a Zone VIII density in the negative when I open the lens up 3 stops from the meter reading for the same 18% gray card, in the same lighting conditions.
Hey that’s easy to understand. Sounds great to me, I can eliminate some variables and focus elsewhere besides a bracket until you vomit technique.
Now if each Zone represented in the Zone System corresponds to a doubling or halving of light from the adjacent zone and Zone 0 is a 0 density (or equal to FB+F) and each doubling or halving of the log value of opacity (density) is +/- .3 from the adjacent zone density, I should expect a zone density of 1.5 for the Zone V exposure and a zone density of 2.4 for the Zone VIII exposure. And for the speed value zone, Zone I, we are looking for a zone density of .3. These values are densities above FB+F.
You can probably see where my first question is going to be. If the targets of the Zone I, V and VIII exposures are “supposed” to be .3, 1.5 and 2.4 respectively; why is it everyone always talks about targeting .1, .6 and 1.15 over FB+F?
I had the thought that it may have to do with the range of the film / developer / time combination. We have 11 zones to place into a density range.
That leads me to another question. If DMax and DRange are based upon development time (leaving everything else the same) how are we supposed to determine the normal development time, if DMax and DRange change due to development time?
Let me try an example just to hash out this problem:
Example A:
DMax: 1.44
DMin: 0.02
DRange: 1.42
Dev: D-76 1:1
Time: 9:30
Zone 0 Negative Density = 0.02 = DMin
Zone 1 Negative Density = 0.16
Zone V Negative Density = 0.73
Zone VIII Negative Density = 1.16
Zone X Negative Density = 1.44 = DMax
These theoretical values based on placing 11 zones into DRange would be altered if I changed the development time. Let’s pretend that an increase to development time of 25% would increase the DMax by 25%.
Example B:
DMax: 1.8
DMin: 0.02
DRange: 1.78
Dev: D-76 1:1
Time: 11:53
Zone 0 Negative Density = 0.02 = DMin
Zone 1 Negative Density = 0.198
Zone V Negative Density = 0.92
Zone VIII Negative Density = 1.444
Zone X Negative Density = 1.78 = DMax
Now of course this affect is to be quite desirable when we are expanding and contracting the contrast of an exposure in the ‘real’ world. But before we can expand and contract we must determine the proper development time by exposing a Zone VIII exposure and checking the density. But what are we checking against? Since both of the above two examples differ from the 2.4 density expected for Zone VIII, which one is right?
And if each zone represents a halving or doubling of light from the previous zone, why is this not the case in targeting densities?
Thanks for all your considerations here. I know this must be pretty nit-picky, but I need to know where to begin.
Best regards,
Rick
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