Preventing highlight blocking in high contrast scenesgreenspun.com : LUSENET : Large format photography : One Thread
I am beginning to experiment with a water bath development process as described by Ansel Adams in "The Negative" (p232). Adams recommends 30 seconds in the developer (Ildord Delta 100, Kodak HC110, 1+19, [F]) with constant agitation and then 1 minute in the waterbath with no agitation.
To get an appropriate contrast range in the neg for my condenser enlarger I have found I need to repeat this cycle 6 times (Adams suggestes 10 but this produces negs that are too contrasty for my darkroom setup).
I have encountered two probelms:
1). In areas on the neg that are relatively flat, I am getting some streaking. Does anyone have a suggestion as to what I might do to avoid this?
2) The shadow areas while retaing detail are very flat. The overall effect has been to compress the entire negative rather than simply holding back debelopment of the highlights. On another BB, Ellis Vernon, suggested (and I'm sure this is right) that modern emulsions are too thin to hold the developer in the way they did for Adams 30 years ago (Indeed Adams does mantion this in "The Negative"). Does anyone have any advice/thoughts on the topic of a modern day alternative to the water bath process Adams described?
(Ellis Vernon suggested trying a method devised by John Sexton using highly T-max developer to achieve the same results. When I find some more details I will try this.
Many thanks (and apologies for the long-winded posting).
-- Simon Rodan (email@example.com), July 25, 2001
Bruce Barnbaum has a highly dilute HC-110 formula that works very well for opening up shadows and retaining highlight detail, he talks of it in his book Art of Photography. A friend of mine uses it, if you are interested semd me and e and I will get it to you. Pat
-- pat krentz (firstname.lastname@example.org), July 25, 2001.
Bruce Barnbaum has a highly dilute HC-110 formula that works very well for opening up shadows and retaining highlight detail, he talks of it in his book Art of Photography. A friend of mine uses it, if you are interested send me and e and I will get it to you. Pat
-- pat krentz (email@example.com), July 25, 2001.
Simon, I haven't tried the water bath development but I can say that I use PMK with FP4 and HP5 and with this combo I haven't blocked my highlights since (without even going into "N-" development) !
With TMAX and PMK, the highlight densities seem to build up quicker but they are still printable. If you don't mind switching developers, this may be a good alternative. PMK negs also work very nicely with condensor enlargers.
You may also consider trying pre-exposure, as an alternative, to increase the shadow values a bit.
-- Dave Anton (firstname.lastname@example.org), July 25, 2001.
If you dont wish to change developers, you might also want to try diluting your developer to twice the recomended dilution. e.i. if you are using 1:9 then try 1:18, you will have to change your film EI, but is easier than doing the two bath thing. With the two bath you run the risk of scratching the film, uneven developing (as you well know) etc. Good luck.
-- Jorge Gasteazoro (email@example.com), July 25, 2001.
I would recommend using a highly diluted developer, long development time, and minimal agitation (just enough to avoid streaking).
For N-4 (HP5, FP4) I use D-76, diluted 1:4, 66 degrees, for 12 minutes, agitating 10-15 seconds every three minutes. This length of time allows for sufficient shadow development, while the reduced agitation allows the dilute developer to exhaust in the highlight areas (and not block them up) For N-5, maybe 10 minutes... For greater compensations, I'd try 1:5. You'll need to experiment with your own set-up and run some tests, etc.
Just be sure when mixing dilutions that you don't reduce the amount of developer used, but instead add more water to get the right ratio. This way you'll ensure that there's minimally enough developer in the solution to carry out the job.
I've heard that, at some point, highlight values can become too blocked-up on the shoulder, so that instead of tones separating during a compensation development, they just come down as a large 'chunk'. For example, if your zones VI-VIII received so much light that all available silver was exposed across this gradation, you would effectively be compressing these tones into D-Max at the top end of the curve, and they would then behave as one value, and would thin uniformly during compensation, yielding a printable value, but with no separation.
This stuff can be amazingly interesting play with. Have fun!
-- Chris Jordan (Massachusetts) (firstname.lastname@example.org), July 25, 2001.
1) The streaking is typically the result of byproducts due to oxidation. The easiest way to try and deal with this is to use a sulfite bath instead of a plain water bath i.e., just add some sodium sulfite to your water bath.
2) Yes, the general consensus seems to be that modern emulsions are too thin to work well with water bath development. The trouble is that the emulsion does not hold enough developer, so while the highlight compensation works, there isn't enough developer in the emulsion to develop the shadows more fully. Some folks have suggested repeated water baths as a way to combat this problem. I've had good luck with the 2 bath development process where I use D23 as bath 1 and a metaborate accelerator as bath 2. I often dilute bath 1 if I want greater compensation. Another option is to use compensating formulae such as highly dilute HC110 or Rodinal with highly reeduced agitation. You can also try specially formulated low contrast developers. A document developer like Technidol or a phenidone-glycin formulae might help. The first thing I would try though is to increase my exposure i.e., that will move your shadows off the toe and place it on a slightly higher contrast area of the curve.
It is also worth noting that the problem you are talking about is unavoidable. Any N- development develops the film to a lower contrast. That has 2 implications. One, your paper (which has a certain scale i.e., can accomodate a certain density range) can now hold a longer subject luminance range. Two, it will reduce local contrast in your print (local contrast is resposible for texture). The second problem is what you appear to be referring to. Highlight blocking was a problem in films in the past where the characteristic curve would just shoulder off i.e., changes in exposure yielded no local contrast in these areas. It is less of an issue with todays films where the films can build considerable density before shouldering off. The biggest issue with todays films is ensuring the shadows have sufficient local contrast i.e., what we want is to put a shoulder on the film without affecting the shadows. I've had trouble putting a shoulder onto some films - they often seem to call for heroic measures. I've come to the conclusion that what works best (at least with the films I've settled with) is use of a dilute deveoper (something like a very dilute HC110 or Rodinal), lenghtened time, highly reduced agitation coupled with increased exposure to support the shadows.
I should also add that a lot depends on the way you visualize a print. Some pictures seem to call for the opposite approach (with low local contrast in the shadows and high contrast in the highlights) - only you can decide what the look you want is. Most folks who shoot landscapes seem to prefer a curve that provides 'open, luminous shadows' (I interpret that as enough local contrast to provide texture which makes it look like there is enough light there instead of Stygian shadows) and are quite happy with a shoulder that reduces the local contrast in the highlights. Its complicated because it also depends upon the distribution of local contrast in your scene - I don't think instrumentation helps here, one needs to develop an eye. Like I said, depends on your vision.
-- N Dhananjay (email@example.com), July 25, 2001.
Thank you very much for all your advice.
-- Simon Rodan (firstname.lastname@example.org), July 25, 2001.
Once again, there is an outstanding paper on THIS SITE on Two Bath Divided Development, including its refinements. Well worth reading.
-- David Stein (DFStein@aol.com), July 27, 2001.