Zone system film development/exposuregreenspun.com : LUSENET : Large format photography : One Thread
As a relative newcomer to zone system control of exposure & development I've tried, rather incompletely, to understand the strong emphasis placed on making negatives that will have a range of values supporting the visualized result, printed on "normal" grade paper.
In particular, I see repeated caution against an approach that ensures all imporant values are contained in the negative, with final contrast control left to selection of paper grades. This form of approach, I've repeatedly read, (without satisfactory explanation) is inferior to manipulating contrast in the negative development stage.
Why is this so? In fact, in my limited experience, it may be better to resist expansion development of the negative, for example, in order to control grain. Normal development with expanded contrast in paper grade selection can produce equally compelling results, no?
-- ernie gec (email@example.com), September 25, 2001
Your theory may result in printing problems. If you try to integrate expansion into the image through contrast filters, you lose tonality. As one moves to higher and higher contrast filters, the higher values approach white, the darker values approach black. Thus important detail at the Zone Vii/VIII areas and at the III/IV areas may be compromised. Split filtering approaches may reduce this tendency somewhat, but not completely and not enough. Expansion to N + 1 or thereabouts, the use of Selenium Toner for increased expansion does not reduce one's abaility to transform the information on the negative to the papser. By the same token, compression of development gives the printer more to work with than does the use of softer filters or lower grade papers.
-- Bob Moulton (firstname.lastname@example.org), September 25, 2001.
Others more familiar with zone system curves can probably better answer your question. But, in a word, you get better results. After seeing my first 4x5 photo developed 25 years ago using the zone system, I immediately tried to replicate that same result by varying enlarger exposure and paper contrast. It wasn't possible. While I could maintain the highlights, the dark areas weren't right. The information simply was not in the negative. It wasn't until I learned and applied the basic zone system tenet of exposing for shadows and developing for highlights that I was able to achieve the result with which I had been so impressed. Even now, I see photographs with poor contrast control, and I think: Nice photo. Poor execution. Too bad.
So, I have my own tenet that it's best to make "adjustments" as close to the object of the photograph as possible. Better to change lighting than add filtration. Better to change the filter than effect color correction in the darkroom. Etc. Since it's not possible to adjust lighting in a scenic photo, it's better to adapt the negative to the constrast in the scene, versus attempting to adapt the paper to a poorly exposed and developed negative.
-- neil poulsen (email@example.com), September 25, 2001.
In large format, grain is not a great worry. Printing on a normal grade paper gives you much greater latitude for print manipulation and control of gradation. Printing on higher contrast grades narrows your range of correct exposure and can limit further manipulation (though modern VC papers help a lot with this problem). I have plenty of old negatives that contain 12 to 14 stops of information, but I can only print maybe 8, if I do a lot of dodging and burning and stay in the darkroom for hours. I think most Zone System pros manipulate their negatives, then manipulate the prints too--they're just trying to give themselves as much room as possible for creative control. I recommend you investigate staining developers such as W2D2 pyro, PMK pyro, Pyrocat-HD, and Dixactol, as they really do seem to allow you to capture a greater printable range on your negatives.
-- Ed Buffaloe (firstname.lastname@example.org), September 25, 2001.
Printing a high-contrast negative on a low-contrast negative give better tonality. Platinum prints are praised for the detail they hold, and this process involves very high-contrast negatives printed on very low-contrast negatives. A. Adams mentions in The Negative that developing negatives to print well on a grade #1 paper would be produce better gradation than producing normal negatives for grade #2 paper. He suggests that grade #2 paper be the target because it allows one to print on grade #1 if needed. With grade #1 as the target, there is no lower paper grade to turn to if needed. I have heard of some photographers who develop their negatives to print on grade #1.
-- William Marderness (email@example.com), September 25, 2001.
Please excuse my mistakes in the above post. I wanted to talk about printing high-contrast negatives on low-contrast papers (not negatives).
-- William Marderness (firstname.lastname@example.org), September 25, 2001.
Having a wide range of contrast papers/filters at your disposal is an excelllent means of expression. However, the higher contrast grades can turn print making into a real chore. You think your neg. is clean? Printing it with #4 contrast will change your mind. Then, plan to spend some quality time with your spotting brush... Not to mention the time spent making the print in the first place. With #2 contrast, a 10% dodge will produce a barely perceptible change; With #4, it's like night and day. Getting it right can be be a very expensive proposition.
All things considered, it's best to start visualizing with the neg.
-- Bruce Wehman (email@example.com), September 25, 2001.
I'll open a bag of worms here but my target is to make a negative that will just barely fit on a #2 paper sometimes with a pre exposure burst because when achieved I believe that has opened the door to some of the most beautiful gallery type fiber based papers. Those negs when developed with pyro will print about as well in Pt/Pd as on a longish fiber #2. I'd hate to be limited to Ilford Multigrade Rapid and a #3½ filter for a fine art print. So there's at least one guys reasoning.
-- Jim Galli (firstname.lastname@example.org), September 25, 2001.
Ernie, This is a good question and has no really simple answer. The most important thing the Zone System does for us is to make sure we don't have to deal with negatives that are way too contrasty or way too soft to satisfactorily print. I agree that, for most negatives, tailoring for a grade 2 paper will give the best results. However, with all due respect to the above contributors, there are instances when tailoring a negative to print on grade 3 (or higher) paper results in a better print. The first, and most obvious of these instances is where small negatives are used and grain is a factor. Even Ansel Adams recommendes tailoring smaller negatives for grade 3 paper to reduce grain. The second instance is when an expansion of local contrast is important to the image to be printed. Since a higher contrast paper separates close values better than expanded development, it is sometimes advantageous NOT to expand some negatives fully by development, but develop them to a point one paper grade under "Normal" and print them on the next higher grade. Among these negatives, although at first it seems counter-intuitive, are all contraction negatives (i.e. all N- developments). Contraction negatives tailored for grade 3 paper and given sufficient exposure to hold the shadow details result in prints with better separation in the mid and shadow tones; exactly the places where separation is normally lost when these same negs are tailored for and printed on grade 2 paper. Of course, these are refinements and modifications of a system of exposure and development that is time-tested and reliable. Part of the reason for choosing "Normal" grade paper for most negatives is, as mentioned above, to give one more leeway in printing. The Zone System is not rocket science, and there are many variables that can affect the final contrast of negatives. If negatives are tailored for a contrast grade that is on an extreme end of the spectrum, then there is no go if the negative is too soft or too hard. Possibly more important is that the curve of lower contrast papers suit the majority of subjects better, rendering subtle highlight separation and retaining good shadow detail which contrastier papers do not do as well. Note however, that this is an aesthetic consideration and that some subjects print better on higher contrast papers (as mentioned above). The main thing that one needs to insure is that there is adequate exposure to achieve the desired separation and detail in the shadows, and that the negative is developed to a point that it fits the printing paper desired, whether it be grade 2 or 3. Simply overexposing and overdeveloping results in a lot of negs that cannot be printed on any available grade of paper, and, if you are interested in grain, the minimum exposure to render the shadows as you want them is best. As one becomes more familiar with materials and gains experience exposing, departures from the "Normal" are used for expressive purposes. Sorry for the long- winded repy. Hope this helps. ;^D)
-- Doremus Scudder (ScudderLandreth@compuserve.com), September 25, 2001.
There are some valid reasons to aim neg development at about grade 2. But leaving that aside for just a moment, you raise a good point. In fact, when Kodak first introduced different grades of paper, it was for the purpose of dealing with errors in development. Try a simple exercise. Assume for the sake of simplicity, that all our transfer functions (film curves and paper curves) are linear - I know they are not actually linear but let's start there. Pick a subject luminance range and try plotting them on a tone reproduction cycle. You will find that as long as you pick matched slopes for the film and paper curves (i.e., low slope film with high slope paper and vice versa), your final tone reproduction will be identical.
Now, in actuality, films and papers have toes and shoulders and that does change the tonal gradations. Also, many of the points made earlier are absolutely valid. Working with higher contrast papers is a pain in the neck. Burning and dodging is hideous, grain tends to be exaggerated by the higher local contrast and as you approach high and low contrast, you have less wiggle room, which is another reason one might not want to aim neg development towards #2.
But I've often thought that the best system would be to minimize the toes and shoulder areas of the curves - that would give us the longest possible straight line section with clean gradation - no tonal distortions. The reason platinum looks so good is exactly for this reason. Platinum actually has a lower Dmax but the neg is developed to a higher CI and the paper accomodates such a neg. The reason it looks good is because in the overall transfer function, most of the function is a straight line - the toe and shoulder have been reduced as much as possible. Most of the overall transfer function is pretty close to a straight line. (And no, an appropriately scaled neg on a silver print will not look the same becuase the silver system will have longer toe and shoulder areas).
The best way that can be done is to develop towards a 45 degree transfer function. Any variation from this will tend to increase the toe and shoulder areas of the overall transfer function (note that this would not happen with straight line transfer functions, its a problem only when we have curves with toes and shoulders). Typical procedures these days for negs is to develop to a CI of about 0.5 or thereabouts, considerably less than the 45 degree line I referred to. Typically one is likely to get better results in the midtones if one aimed for a higher CI - that is, a neg aimed at grade 1 is likely to yield somewhat cleaner midtone gradation. However, that leaves you with no wiggle room. Any errors and you are sunk.
One reason so many folks like the way Azo looks, I suspect, is because the final result has long straight line characteristics. That reduces the distortions due to toe and shoulder - my subjective opinion is that a neg aimed at Azo can be developed slightly longer than one aimed at an enlarging paper. All of this is further complicated by the fact that different manufacturers adopt different methods of accomodating unruly negs. Some papers vary mainly in the shape of the toes and shoulders. Others vary the slope of the straight line section also. So given all of these complications and associated problems alluded to by others, its probably preferable to aim at the middle of that scale. Cheers, DJ.
-- N Dhananjay (email@example.com), September 25, 2001.
Sorry for the typo at the end of my second paragraph - those are reasons to 'aim at grade 2', not to 'not aim development at grade 2'. DJ
-- N Dhananjay (firstname.lastname@example.org), September 25, 2001.
Thankyou all so much for your thoughtful responses. This is a fantastic site and without question, the contributions are more informed than any other net based resource.
-- ernie gec (email@example.com), September 25, 2001.