N+1 what is the %

[Stuart]

Hi
Need some help with the zone system.
N+1/N+2 and so on,I get it but what is the % used?
EI: N+1= normal + 10-15-20-25%
Regards
Stuart.

 

[David A. Goldfarb]

There is no fixed percentage. It depends on the film, developer, temperature, dilution, and agitation pattern. You might try a range of development times, and N+1 will be whatever development time gives you a Zone VII density equal to your target Zone VIII density for "N" development.

 

[juan]

David is correct, but I think the generally accepted increase for a first guess is 20% above N for an N+1. You might try there and see if that gets you close.
juan

 

[RalphLambrecht]

Stuart

To me N means that you want to capture the normal subject brightness range of 7 Zones (from I.5 to VIII.5) in the normal negative density range of 1.2 (0.17 to 1.37) to get it on the normal print density range of 1.9 (0.07 to 1.97). The resulting negative gamma can be calculated from:

y = 1.2/(2.1-(N*0.3))

The development time it takes to create the required negative gamma depends highly on the materials used. I always expose and develop 5 sheets or rolls and develop them at 4, 5.5, 8, 11, and 16 minutes. That gives me all the data I need to determine the development times for N-2 to N+2. However, without any testing you can use the following as a rough guide or rule of thumb:

For a normal contrast, bright but cloudy day, cut the manufacturer’s recommended film speed by 2/3 stop (i.e. ISO 400/27 becomes ISO 250/25) and the recommended development time by 15%. The increased exposure will boost the shadow detail, and the reduced development time will prevent the highlights from becoming too dense. For a high-contrast sunny day, increase the exposure by an additional 2/3 stop (i.e. ISO 400/27 now becomes ISO 160/23) and reduce the development time by a total of 30%. Stick to the suggested film speed and development time for images taken on a low-contrast gloomy day.

 

[reellis67]

I wondered about that too, until I read Minor White's book "Zone System Manual". Ansel explains it in his 'Basic Photo' series of books, but my editions (very early) did not have a lot of detail while the later versions (I understand) go into it more. There is a series of tests that you run to 'calibrarte' a film and developer combination. You then know specificaly how much to adjust for N+1, N-1, etc.. The point of the system as I understand it is to have very tight control of the negative, so guessing seems like it would be more along the lines of 'expose for the shadows, develop for the highlights'.

- Randy

 

[noseoil]

Stuart, this is a confusing subject and there really isn't a simple answer as you have found above. One thing I had trouble understanding was the relationship between film density and the actual print, in stops of exposure and development. If we use the "normal" relationship about film density being .3 units of density per stop, we have a full stop on the film. Paper doesn't see 8 stops of density, as film can, so a full stop (.3) on paper can actually be more in the print. Sorry to be confusing, but if paper can see 5 full stops, a full stop of development in the film can be more than a full stop on the paper when it is printed. This is why the film and paper work together to form a print.

Try 20% as was suggested (Juan has given you a good number to try), but remember the film can only do so much. Tri-x can only deal with about 1 1/2 stops of expansion before it has reached its maximum contrast. Efke 25 can deal with about 5 stops of expansion, a bit more than we usually need. tim

 

[Claire Senft]

Not to be picky but N+1 = a variety of possible changes. It would be used for Zones >5 generally and could be any of the following: 6 to 7, 7 to 8, 8 to 9, 9 to 10 Each will give different results. Each would require a diiferent development time.

For example: If an N+1 in a particular case meant that Zone 6 was to be moved to zone 7 than any zones in the subject that were higher than zone 6 in the original N scene would with an N+1 development recieve more of a boost in contrast than 1 zone. If N+1 in a particular case meant a desire to move zone 9 to zone 10 than any zones in the scene that were<9 would receive less than an N+1 boost.

Each variation would require its own testing.

Each film would have its own characteristics. Each developer would be somewhar different.

You will find that more modern technology films, such as 100 TMax will require less additional development, generally speaking, than films of the 'older' style.

Every scene chosen will present different flare opportunities to help make your changes imprecise.

Obviously changes in paper contrast help to deal with these irregularities.
The use of a spot meter also complicates any precision. The meters have less than a linear response to color, IR an UV. This is before even considering the distance that a reading is taken from..a significant variation.

 

[RalphLambrecht]

Claire is right. There are almost too many variables to really control the Zone System. One way to simplify it, without losing the benefit, is to fix the origin of contraction and expansion. I like to fix this point at Zone I.5. This reasonably controls the shadows with exposure and leaves the rest to development.

 

[noseoil]

Stuart, as a follow up to my post... I use zone 3 (full texture in shadow) and zone 7 (full texture in highlights) as my point of departure. This is a decision I have made, based on a step tablet print I sent to from Stouffer. It is just a strip of paper with the zones printed on it. While it is not at all scientific, it has given me a point of reference I can use to determine a "normal" development in the print. The numbers (.3, .1 above film base plus fog, etc.) didn't mean squat to me at first, just b.s in words. The print, I can look at it and I can understand what it means.

Claire has given you a wonderful explanation of this relationship, why you can't just pick a number for a film and use it. You will learn as you go, just take small steps. Best, tim

P.S. If you end up with a headache after reading this stuff, you are learning.

 

[Stuart]

Thanks everybody for taking the time to reply.
I thought this question was going to make my life easyer.
Tim is right I feel a headache coming on.
But I´m a little wiser.
Thanks again
Stuart.