Well this thread has certainly travelled a long way from the OPs question which was In general may I know what effect it will incur on the contrast when I increase the Sodium Metaborate say from 12g to 15g. - to which, I believe my post #8, gives a helpful response.
My personal take is that two bath developers encourage people to believe that being sloppy is OK. Gerald.
Sorry Gerald but sloppy is not in my vocabulary (see my specific point in post #8). I always advocate that, irrespective of what developer is used, the photographer must ensure that time, temperature and agitation are all carefully controlled. Also, to your point about normal developers what exactly does this mean? A developer is simply a means to an end. People choose developers on the basis of the results that they produce. In practice, one can, with careful testing, produce good results with virtually all developers. However, when using roll film one is confronted with the problem that individual negatives ideally require differing development to adequately reflect varying subject brightnesses. This is where a two-bath developer can be of great assistance.
However, continued use results in one never learning how to do things properly. Gerald.
Two-bath developers require that the photographer undertakes suitable testing just like any other developer. I would question what you mean by how to do things properly. If the word properly means what most people do as the norm I can not concur. However, if properly means achieving the desired results then of course every photographer needs to learn how to do things properly.
You seem now to be simply saying that one should expose and develop in such a way as to make images as easily printable as possible, which seems both unarguable and not what you said in the first place. Pdeeh.
In the first place, I answered the OPs question to the best of my knowledge. I did not state that one should expose and develop in such a way as to make images as easily printable as possible. Rather, I was suggesting that the use of two-bath developers can help a photographer to achieve consistent negatives that they will be able to print in a manner that achieves prints that match their vision. For example, if you have undertaken suitable tests with any combination of film and developer you will achieve printable negatives for most scenes. However, if you then wish to photograph something that has a higher than normal subject brightness range you are confronted with two options. Either you apply N-minus development which will affect all of the other images on your roll of film or you process normally with the problem that your highlights may be so dense that you cannot produce an adequate print. The use of a two-bath developer eliminates this problem.
Surely, if the final result is print that reflects the photographers intentions, how they actually arrived at that destination is largely irrelevant? Chris.
Exactly my point. The final print represents the statement that photographer wishes to make. There is no such thing as a proper way of doing this because the the route followed is not what the viewer sees but rather the final result. My principal concern when teaching people is to provide them with a repeatable and consistent system of exposure and development that will deliver prints that match their vision.
For the novice photographer their use encourages sloppy technique. Developers like BTTB are particularly hard to control. There are too many variable for the novice; time, temperature, and alkalinity of bath B. They have a certain glamour in the oldest sense of the word. They present the illusion of being something that they are not. Gerald.
As per my post #8, I have no time for sloppy technique. Developers such as BTTB are not particularly hard to control. Quite the contrary, two-bath developers compensating effect reduces the margin of error in comparison to developers that are formulated to utilise the super-additive affect. Whilst I encourage everyone to be fastidious in their processing regime, a 5% error in time, temperature or agitation when using a developer such as HC110 at Dilution B will have a significantly greater effect than the same margin of error when using a two-bath developer. Also, alkalinity does not vary at all because Bath B is always made with Sodium Metaborate. In fact, BTTB two-bath developer is so simple I fail to comprehend how anyone could mix it up wrong. This does not mean that people should be sloppy in the processing their films but rather is a simple demonstration of the fact that two-bath developers are not significantly more hard to control.
I do see and empathise with your points but regrettably out of 36 exposures two of which may be of higher contrast that would benefit from a divided developer I must commit the rest of the roll to the same treatment. As with the "pure" zone system which was designed for processing individual exposures or as I have previously done with my V system and multiple backs a roll of exposures requiring the same development technique that is a luxury few can commit to. Chris.
Using multiple backs on a Hasselblad to allow for matching the processing to the subject brightness range when using standard developers works very well and is something that I employed when I used to make natural landscape photographs. However, it is not something available to most roll film users. The key point about divided development is that it will control subjects with a higher brightness range
without having a negative effect on the other exposures on the same roll of film.
At the end of the day it really does not matter what processing technique you employ so long as you achieve the results that you desire. My experience has been that my students move rapidly and confidently quickly forward from novice to technically adept when working with two-bath developers. The consistent nature of the results encourages them to concentrate more on what they are photographing rather than the technical aspects. Naturally, with time, some choose to employ other developers that better match what they want to achieve (for example, if they gravitate towards low light street photography they may well choose to develop Tri-X in DDX). The key point however is that they are making these changes in an informed manner. In the previous example, they understand how to achieve a high level of good tonality but recognise that they will have to sacrifice a certain level of shadow detail to achieve the results that they want.
Bests,
David.
www.dsallen.de