Response to what happens with REALLY long dev't times?

To begin with, I would not consider a 7-8 stop range of brightness as flat lighting. My guide is as follows ; most modern films can actually handle a brightness range of 4 - 4.5 stops, i.e. from zone 3 to zone 7.5. If that is the range I am looking at, and if the placement of a mid-tone value where I want it will allow the shadows and highlights to fall appropriately within that range, I will go for an N EI and development.

If neither of those two conditions hold, then either N+ or N- will apply.

For example, if the brightness range is, say, 3 stops, and I want to emphasise texture by expanding the range of local contrast in the mid- tones, I would go for an N+ EI and development. This might mean rating the film EI at 1/3rd - 1 stop higher, and lengthening development by 30 - 40%.

Alternatively, if the brightness range is, say, 7 stops, of which, say, 4 stops will fall as highlights because of where I place the mid- tone that determines exposure, I would look to an N-2 to compress the highlights to a 2 - 2.5 stop range. If I placed my midtone elsewhere, e.g. such that 3 stops fell as highlights, this would probably mean an N-1 contraction. N-, for me, entails rating the film at a lower EI - 2/3rds - 1 2/3rds of a stop lower, and reducing development by 20 - 40%.

At the end of the day, it depends what you want to do. N+ can be used to emphasise texture and expand the range of contrast in the mid-tones, and the lengthened development time will produce rather more grain, and enable you to manage edge effects - this is what I described to you earlier in your recent question on Agfa APX100 - but you have to be careful where the range of highlights will fall, as you do not wnat these to go beyond zone 7.5.

Alternatively, N- can be used to reduce texture and contrast in the mid-tones, allowing a sort of fuzzy glow in portraiture, for example.

I hope I haven't confused you, and I am sure that some will disagree with the above, not least with the starting premise that films can only handle a meaningful range from zone 3 - zone 7.5, but it seems to work in practice for me.

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