Is N+1 really necessary?
Say I have a low contrast scene where the shadow value falls on zone III and highlight on zone VI which I'd like to be zone VII in the final print. What differences in a final print would I see if I printed a neg with a range from zone III to VI (given N development) printing the highlight up to zone VII using a higher contrast filter vs. giving that negative N+1 development to bring it up to zone VII and printing with a normal contrast filter?
My experiences have been that a lower contrast negative printed using a higher contrast filter gives more pleasing mid-tones, and highlights with more contrast than printing a neg given N+1 assuming there is adequate shadow detail. N+1 negs seem to have the mid-tones pulled up in value as well.
Anyone have thoughts, suggestions on this?
Yes and no! I think it depends on the scene you are photographing and also how you measure your light.
If it is a foggy scene with no clearly defined subject i think your approach is good, leave it at about 4 or 5 zones on the film.
If it is a scene with a a subject that you want to stand out i would suggest processing the negative with a +1 or +2 development time to get some micro contrast which i have a hard time getting if i don't develop the negative to more than 5 zones. I do always try to expand the grays as much as i can processing the film but i need to know where my highlights are when i expose the film so i don't blow them out in the processing stage.
Micro contrast is an interesting topic in itself. How is micro contrast enhanced differently by giving N+1 development vs. increasing contrast at the printing stage?
By using N+1 development of the negative you mostly just achieve your objective of moving Zone VI to VII and pretty well leave alone the shadow values. Using a higher contrast filter expands the contrast of everything, possibly compromising the shadow values. I suspect the choice should be made in light of long experience with the materials used.
Unless you photograph extremes of light with very high or low contrast lenses, a single development time should be fine if you print with multigrade paper or you have a wide selection of paper grades.
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I'm not sure I can explain my experience well enough, but I'll try...
Originally Posted by brian steinberger
This was something we explored while I was in college (1970's). In a very controlled studio environment, we exposed two sheets of film- one N, and one N+1. We printed to match the highlights, using a higher grade filter for the N exposure, lower for the N+1. There was a slight, but definite difference in the values of the midtones. The "higher" values in zone v lightened ever so slightly. I think it's easier to understand if you envision zone v not as an exact value, but as the range between the lightest zone iv value, and the darkest zone vi value. I'm not sure my explanation makes any sense but, put simply, if you stretch the tonal range of zone vi, there is some expansion of parts of zone v, too.
In short i find it much easier to make prints if i have a negative with a large tonal range and as many zones as i can get safely in my negatives. It is easier to print " down" than up as far as i know but, i don't know it all so take it as what it is.
I suggest that you go out and find a scene with similar ligthing and shoot one sheet or a roll each way and process accordingly. It's an interesting test and a good learning experience and does not cost very much.
Brian, N+ is an interesting topic. There are several factors to consider, including film format and film type.
Generally, both micro-contrast and graininess increase (graininess, rapidly so) with increased development. High micro contrast (essentially local contrast between very small areas of different density) tends to make it more difficult to maintain the most subtle highlight detail/separations. It is also "amplified" to some extent in the enlarging process, although this is generally less of a problem with today's films and diffusion enlarging helps too. Graininess, well that's obvious. It therefore follows the smaller the negative, the more pronounced these plus-development downsides. It is not something I would worry about with large format (unless the expansion is extreme), but with 35mm or medium format the negatives can outweigh the positives (to my eyes).
Further compounding the issue with smaller formats is the fact we are often using tabular grain films in those sizes, and it has been argued tabular grained films in general have higher micro-contrast than "traditional" films. This is one reason many people prefer, particularly with tabular films, to downrate and cut back on development in general. That lowers micro-contrast, and softer negatives are also both sharper and finer grained (again, not an issue in large format). However the tabular-vs-traditional differences are less than they once were for two reasons, 1) current tabular films are better than they were in the beginning, 2) traditional films like FP4, Tri-X etc are more tabular than they once were.
The other thing to keep in mind with most all of todays films is that in general, zone system controls are a little more tricky when trying to expand or contract macro contrast. In the zone system +/- heyday most of the films had more s-shaped curves. The low-to-mid values would move substantially less than the highlights. However most current films are short toe, straight lined films. So with expansions, more of the curve moves upward, which means the overall increase in contrast from shadows to highlights is lessened, while local contrast will tend increase along most of the curve, even down into the shadows. This can be thought of as more similar in effect to increasing the grade of paper or filter in the enlarging process.
What I would normally suggest to people using small or medium format film and wanting maximum image quality with expansions, is to first chose a film that inherently has properties that most resemble what you need, and use development as a secondary control. So for example if you want more contrast, use PanF rather than say giving FP4 or HP5 plus development. Granted this is not always possible in the field.
Incidentally, for small and medium format films, one way to reduce the increase in graininess for mild expansions up to N+1, is to selenium tone the negative. I find I can get ~N+1 with this technique and the increase in graininess seems to be visibly smaller than with N+1 development.
Last edited by Michael R 1974; 11-25-2011 at 08:44 AM. Click to view previous post history.
"Increasing the contrast of a print does not make the whites whiter; it makes the blacks blacker." -----(Anchell, The Variable Contrast Printing Manual). Changing filtration settings in the enlarger does not afftect the whites as long as the paper and filters are speed matched, meaning that you can change the filtration and keep the same basic exposure while not affecting the whites of the print. This is one of the great advantages of using VC paper.
What differences in a final print would I see if I printed a neg with a range from zone III to VI (given N development) printing the highlight up to zone VII using a higher contrast filter vs. giving that negative N+1 development to bring it up to zone VII and printing with a normal contrast filter?
If you want to affect the most important highlight value in the final print, then do it with development controls. N + 1 is absolutely necessary when you consider that old saying that is so very true----"expose for the shadows and develop for the highlights".
The only other thing I would comment on is that you said the shadow value "fell" on zone III and the highlight "fell" on zone VI----with black and white negative film, you base the camera exposure on the "placement" of the shadow on the gray scale in which case it's the highlight that "falls" on the grayscale relative to the shadow placement. All other luminances "fall" on the gray scale relative to the "placement" that is made in determining the camera exposure.
The shape of VC paper's HD curve changes as you change the contrast filtration. At low contrast grades the curve is bumpy and may have flat spots. At higher contrast grades the curve becomes much smoother.
Because of this the look of a lower contrast negative printed with a higher contrast filter can look better than if the negative had been developed to a higher contrast and a lower contrast printing filter had been used.
There is an application note on the Darkroom Automation web site that explains the source of the low-contrast VC paper problem:
[It's the same app note that has been on the web site for a year or more. Please email me if this (or other) app note displays with a 'Star Trek' font on your computer.]