How do I determine N+1,+2 etc.

I am wanting to use the zone system and I understand the metering for the respective zones, but what I don't understand is how to determine the N+1 or N-1 as the case may be. If my normal development time is 10 minutes, does plus 1 equal 11 minutes and minus 1 equal 9 minutes. Is it simply a 10% increase/reduction since there are 10 zones (0-9)? Or is it something more complex. I am planning on doing the film tests and stepwedge tests in the near future. Do I need to do these first? I have gotten the basic information about the ZS from "Way Beyond Monochrome". However, the sensitometry stuff really confuses me, is it really necessary to have an understanding of this as well?

g

A certain percent change in development time does not necessarily produce an equal percent change in highlight density. If you go back to Adams' _The Negative_ it's all pretty intuitive.

Once you determine your film speed, you determine what Zone VIII density makes a good print with your print process with a normal contrast scene. Your N+1 time will be whatever it takes to get Zone VII to that same density, and N-1 will be whatever it takes to get Zone IX to that density, etc.

Ggriffi,

What type and format of film are you using, how are you determining exposure, and how are you processing it?

-Peter

Peter De Smidt said:

Ggriffi,

What type and format of film are you using, how are you determining exposure, and how are you processing it?

-Peter

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Peter, right now I am using efke/adox 100 in 4x5. I use a 5 degree spot meter and process (rodinal 1:50) in a combi plan tank. I realize that I do have some work to do (film testing and such). Up until now, I have just gotten an overall reading and shot using that.

g

I recommend the book, "Creative Black & White Photography" by Les McLean.
It is a highly regarded book on a creative approach to photography and darkroom. In it he offers a simple, detailed, straightforward introduction, along with test methods, to negative contrast control through exposure and development. Personally, I prefer to use a visual approach to this rather than getting caught up in doing it all by the numbers.
Does it work? It is awfully hard to argue with his results.

The visual approach and the sensitometery both can work. I find it easiest to learn the visual approach if you have someone to show you, and if you have access to fine prints in museums or galleries. If you have to learn from books and the internet, a densitometer and some numbers will get you in the ballpark of recognizing what a good negative looks like.

Flotsam said:

I recommend the book, "Creative Black & White Photography" by Les McLean.
It is a highly regarded book on a creative approach to photography and darkroom. In it he offers a simple, detailed, straightforward introduction, along with test methods, to negative contrast control through exposure and development. Personally, I prefer to use a visual approach to this rather than getting caught up in doing it all by the numbers.
Does it work? It is awfully hard to argue with his results.

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Neal, guess I will take a look at that one. I started with "WBM" because it came up on one of the searches that I did here. I would rather work by "feel" than by "structure", if you will, for lack of a better term. If there is one thing that I really like about shooting 35 compared to 4x5 is that sometimes you just go shoot.

g

David A. Goldfarb said:

The visual approach and the sensitometery both can work. I find it easiest to learn the visual approach if you have someone to show you, and if you have access to fine prints in museums or galleries. If you have to learn from books and the internet, a densitometer and some numbers will get you in the ballpark of recognizing what a good negative looks like.

Click to expand...

David,

I wouldn't disagree with you at all. Without going into all the details, for the most part apug and books are where I learn now. And believe me I have learned a lot here. But I have always felt better working by feel than anything else. That being said, without someone to get feedback from is why I am trying to learn here and in books.

g

ggriffi said:

I am wanting to use the zone system and I understand the metering for the respective zones, but what I don't understand is how to determine the N+1 or N-1 as the case may be. If my normal development time is 10 minutes, does plus 1 equal 11 minutes and minus 1 equal 9 minutes. Is it simply a 10% increase/reduction since there are 10 zones (0-9)? Or is it something more complex. I am planning on doing the film tests and stepwedge tests in the near future. Do I need to do these first? I have gotten the basic information about the ZS from "Way Beyond Monochrome". However, the sensitometry stuff really confuses me, is it really necessary to have an understanding of this as well?

g

Click to expand...

There is no accurate way to determine what you want to know without densitometric readings. Each film/developer combination will respond differently. Complicating this still further would be your agitation procedure and your water temperatures. The next thing that enters into this is the ES of the paper that you are using.

I will say the Efke PL 100 with Pyrocat 1-1-150 (minimal agitation in BTZS tubes) times are SBR 7 (N dev) 16 min, SBR 6 (appr N+1 dev) 28 min, SBR 5 (appr N+2) is 38 min. This is with 70 degree developer temperature and deliveres a negative DR of 1.35 in my darkroom.

By the same token, using the same film and developer for a negative that delivers a 1.65 DR (for Azo) requires times of 26, 38, and 50 minutes for the same expansions.

I would suggest reading the procedure for testing. Doing the tests as outlined and then I would be happy to read your negative densities if that would help.

Flotsam said:

I recommend the book, "Creative Black & White Photography" by Les McLean.
It is a highly regarded book on a creative approach to photography and darkroom. In it he offers a simple, detailed, straightforward introduction, along with test methods, to negative contrast control through exposure and development. Personally, I prefer to use a visual approach to this rather than getting caught up in doing it all by the numbers.
Does it work? It is awfully hard to argue with his results.

Click to expand...

Again Neil, I would have to agree with you. I picked up this book at a borders books about a month ago. I'm about 80% through it and think its a great book!

Ggriffi,

With the film in question, you'll probably need to increase/decrease film development by about 30% for a +1/-1 development. You will also gain/lose approximately 1/3 stop of speed, gaining for the +1 development and losing for the -1.

I don't think that you need any more books. WBM is an excellent book, with enough info to get your system under control. I'm going to disagree, though, that you need a densitometer, although they are certainly very handy. Instead, I'd get a Stouffer 4x5 step wedge with 31 steps in increments of .1. Make a 5x7 (or so) enlargement of the step wedge on your regular paper at your 'grade 2' setting. Develop normally. Count the number of step from just lighter than the first visually maximum black to the wedge just slightly darker than pure white. By referencing the charts in WBM, you will now know exactly what contrast grade this will give you. If you are actually grade 2, you're set. If not, adjust contrast to give a grade 2.

Now shoot an evenly lit black card in shade. Focus on infinity so that you don't inadvertantly lose light due to a bellows factor. Put your meter on EI 25. Meter the black card. Close down 4 stops. Take an exposure. Open aperature 1/3 stop. Expose another fram. Do that 6 times. Develop your film. Pick the negative that where the image area is slighly denser than the clear edges of the film. If it was your first negative, then your EI is 25. If the second, then your EI is 32, then 50, 64, 80, and 100 respectively. It's better to give slightly more exposure than less exposure.

Now do a series of exposures of an evenly lit matte white card. Set your meter to the EI you came up with in your first series. Meter the card. Open up 3 stops. Make a couple duplicate exposures. Develop one sheet. Put your negative with a zone I density in your enlarger. You know, the one from the film speed series. Do a test strip in 1/3 stop increments or so, with your grade 2 filtration. Find the first step that's maximum visual black. That's your exposure. Now put the Zone VIII negative, the one you just developed, into the enlarger, and expose part of the paper for the time just determined. Cover half the paper with an opaque object. You want the part of the paper exposed to be just slighly darker than pure paper white. Look at your test strip to know what I mean. Look for the one that's just slighly darker than white, that's what you want.

If it's just right, you're done. If it's darker than it should be, you need to develop more. Increase development by 20% and check again. If it's lighter than it should be, reduce development by 20%. You should then be very close. You can develop a few more sheets if you need to.

You now have your N film speed and development time. To find your N+1 time, set your meter to an EI 1/3 higher than your normal one. Meter a white card... Open up 2 stops and expose. Develop for 30% more than normal. You want this negative to be the same density as the Zone VIII one from the normal test. Compare them on a light table, contact print both on a sheet of paper, or find a friendly person with a densitometer. If they're the same, your good to go. If not, expose another sheet and develop for more or less as the situation warrants.

You should now see what you need to do to figure out your minus 1 development. You will lose approximately 1/3 stop of speed. Note, that's just my experience with my materials. You might lose/gain slightly more or less.

Have fun,
Peter

I have both WBM and Creative Black & White Photography, and will say both are have to have books IMO. The difference would be that Les' book is a bit easier to someone just starting with controlling exposure, where WBM is more detailed. That said, the WBM has a nice little zone calculator in the back that I found the best way "for me" to get a handle on zone exposure. That said, have learned a lot by taking the advice given on this forum, by Donald and others here. Have had some successful exposures due in part to their help....the less than successful were my fault

One other note, I have been using a Polaris meter with a 5 degree spot attachment on it and it seemed to be working pretty good....recently picked up a 1 degree and the difference is a bit surprising. Now if you decide to try BTZS, then a good incident meter will be what you need, but if you plan to use the zone system I think either compare your meter with another (1 degree if possible) or consdier one of the 1 degree meters....just my own thoughts.

ggriffi,

There are some excellent replies to your question, but the basic approach is what you need, right? If you have a "normal" scene where you know the print will place zones 3&8 (or 3&7, or 2&9) properly, there is no problem. If the print is "flat" or dull, more development is needed to bump the high values. Take two shots and guess at development time. If one works well enough, write down the time. Same for n- times. A rule of thumb can be 30%, but this depends on too many variables with respect to film, developer, temperature, agitation, etc. Most important thing is to write down what you have done, learn from it, then apply it to a new situation. Mistakes are only mistakes if we don't learn from them. tim

I recommend you obtain a copy of John Schaeffer's "The Ansel Adams Guide: Basic Techniques of Photography, Book 2" and a Stouffer step wedge. (The smaller 1/2" x 5" T2115 model will do and costs about $9 through Bostick and Sullivan, an APUG sponsor.) In chapter two of that book Schaeffer compiles and simplifies much of the information in Adams' original zone system book series and he illustrates a simple way of doing the film testing by sandwiching the small step wedge above a sheet of film in the holder and exposing the combo to a zone X target. (For example, a white card metered to middle gray zone V and then given 5 stops overexposure.) After developing the film, the step wedge has provided the entire range of exposures on a single sheet of film. Plotting the densities is actually pretty easy and this procedure will provide you with information about the true film speed and your development all in a single sheet of film.

You should also take the step wedge and determine the exposure scale of the paper you'll be using by making a contact sheet of it. This will give information on for example, what density of the stepwedge (or on your actual pictorial negatives) will print as middle gray, zone V. Let's assume that density turns out to be .65 above filmbase-fog level. In fine-tuning your film speed and development for normal (and N+/-), you can use that information to target certain density values and treatments. If Zone V needs a density of .65 to print middle gray on your paper and that coincides with say step #5 on the wedge, you can then compare the sheet film test densities with the step wedge simultaneously on a light table. This procedure is surprisingly accurate and eliminates the need for an expensive transmission densitometer. You will also be able to tell which densities print for example as threshold grays, skin tones which fall in various zones, etc.

Once you have determined the target densities for the various print values you are then ready to determine the proper development times for N+/- treatments.

Let's say your print target value for zone VIII turned out to result from a density of 1.20 on the stepwedge (and that corresponded to step #9 on the wedge) and that zone VII resulted from a density of 1.00 (step #7) and that threshold light gray zone IX resulted from a density of 1.40 (step#10). In order to determine the N+1 development time, you need to find the (expansion) development time that will take the exposure normally producing zone VII (1.00) and develop it so that it results in the density associated with Zone VIII (1.20) on your film. The (contraction) development N-1 would work similarly in that a Zone IX exposure (1.40 density normally) would be developed to produce the Zone VIII density of 1.20.

Note that the density values I've given are only examples and they may vary depending on your specific materials and procedures, but I hope they illustrate the concept of N +/- development clearly. You really have to run a few simple tests to get a handle on it but it is not as complicated as it seems once you take the plunge. I also can't overestimate how useful the stepwedge actually is. It is a very low cost alternative to a transmission densitometer and will help you see exactly what is going on with your printing paper as well as being a useful tool for determining film speed and proper development times.

Joe

By the far, the easiest book I have seen to date to explain all this and work you through the testing procedures is Fred Picker's "Zone VI Workshop" book, which can easily be bought on Amazon or eBay for around 10-15 US dollars. You can do all the tests in one Saturday or a whole weekend, if you're doing more than one film, and you will have your proper exposure index, N development time, N+1 and N-1, as well as "proper proof" time for your paper and developer.

It's easy, quick, and painless, and the results are very accurate because it's based on VISUAL determination (if it looks like Zone VIII, then it is a Zone VIII).

Good luck! I've taught many people in workshops how to do this using Picker's approach and it's so easy it's almost scary.

The first thing you need to understand is what is meant by N-1 or N+1. The fundamental meaning is a change in development that results in a shift i highlight tonalities by exactly one zone. There is a specific, scientific definition of what that means in terms of negative density, but functionally it translates into Zone IX becoming Zone VIII (N-1), or Zone VIII becoming Zone IX (for N+1).

How you achieve N-1 or N+1 is an entirely different matter. The only way to know for sure is to do testing in your darkroom, with the chemicals and film that you normally use. Most people fine that a one zone compression or expansion requires a change in development time of around 30%, more or less.

I want to thank everyone for all the answers that were given. Now I just have to figure out which way I want to go as far as the testing. One more question that I have can I use the stepwedge for 35mm and not get one for 4x5?

g

ggriffi said:

...One more question that I have can I use the stepwedge for 35mm and not get one for 4x5?

g

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Yes. You'll be able to compare densities on the lightbox, make contact or enlargement determinations of paper scale, etc. What you won't be able to do is the one-shot Zone X exposure test ala Schaeffer because of the physical size difference between the film and the stepwedge. Otherwise, the densities are just densities whether they are on the stepwedge or a pictorial negative.

There is no accurate way to determine what you want to know without densitometric readings. Each film/developer combination will respond differently. Complicating this still further would be your agitation procedure and your water temperatures. The next thing that enters into this is the ES of the paper that you are using.

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While a densitometer works fine and can save you some testing time, it's not at all necessary.

For all Fred Picker's bombast, he did outline a simple and reliable method of testing for both film speed and development times. (This is a modification.)

Buy a small (1 1/2 inch square) .10 Wratten neutral density gelatin filter. Gelatins are delicate so handle it with care.
Expose several sheets of film of a blank, non-testured surface in open shade in half-stop increments for a Zone I density. (4 stops down from your meter reading; meter should be set at recommended speed for the film).
Develop at recommended development time for that film.
Over a light box, place the Wratten .10 filter over a piece of the clear film leader and take a reading with your spot meter held flat against the film/filter sandwich. Use the EV numbers on your meter.
Let's say your EV reading is, for example, 9.6. This is your FBF (film-base-plus-fog) number and will remain constant for that particular film.
Now, lay each of your test negs on the lightbox (without the filter) and read each of them in turn. The one that is equivalent to your FBF reading is your Zone I and this gives you the speed of your film.

Now shoot about 4-5 more sheets of film, using your tested film speed (same setup), but this time at 3 stops over the meter reading for Zone VIII.
Develop the first sheet at recommended time.
Find the enlarger exposure that gives you the minimum time to get a maximum black. (Clear film in the neg. carrier--test strip in 3-second increments. The strip that is the first one to be indistinguishable from the one following it is the correct time.) Let's say, for example, 9 seconds at f/11.
Now put your test neg in the neg carrier and expose a test strip for your MTMB exposure of (e.g.) 9 secs., covering half of the test strip during the exposure.
If you cannot see a difference between the uncovered and covered portion of the test strip, (pure white), your development time is too short. Develop another of your test negs at 20% more time, and do another test print. You're looking for a very light gray, just distinguishable from the pure white of the covered part of the strip. If it's darker than that, you've overdeveloped, and your Normal development time is probably somewhere between the recommended time and your 20% increment. At any rate, splitting the difference will be "close enough for government work" as Pat Gainer is fond of saying.

With normal time established for that film at that speed, use your remaining test negs to establish an N+ and an N- time. N+1 is approximately one stop difference in density, etc.

I rarely use more than an N+1 and almost never more than an N-1. Depends on the film, and T-grain films like T-Max or Delta don't seem to need as much over and under development as older-type more conventional films.

This sounds complicated, but in practice, it's easy enough, if a bit time-consuming and tedious. But once you've done the testing, you won't have to re-do it until you decide to change films. And even then, you can cheat and make a guesstimate based on your previous results. Most times, you'll get fairly close on the first guess, and can fine tune it by eyeball rather than repeating the whole procedure again. It's worked for me.

Maine-iac said:

...
Buy a small (1 1/2 inch square) .10 Wratten neutral density gelatin filter(BIG SNIP)... Most times, you'll get fairly close on the first guess, and can fine tune it by eyeball rather than repeating the whole procedure again...

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Henry Horenstein's B&W book provides yet another example of practical zone sytem testing using such a ND filter.

Regardless of how you do it, it all comes down to a visual assessment. You can eyeball things and get great and very useful results. The system is really easy and most books and descriptions have it overblown. Take the plunge.

Joe