Need some clarity: N-1 developing vrs 1 Stop less exposure

[peter k.]

Curiosity question more than anything else.
Learning a new sheet film, Tmax 400, and developing it in different developers, Xtol, D-76 and Hc110 to see which we like the best. Shooting it at 400, to start with and using specifically to get started, the Kodak reference for temp and timings. Later on we will experiment, on different asa ratting, ect, ... but right now want to set the basics for my developing.
Noticed on a group, of same subject, that one shot was shot a stop underexposed, . and are liking the look of that one the best.
Which somehow raised the question, what is the difference in result in exposing and then developing n-1 vrs exposing one step less in exposure and developing for the normal time?
The only thing we could come up with is that with n-1 developing you would have more control as the timing is flexible vrs a 1 stop underexposure is very set.
What would be the difference? I suppose we could get educated and test this by shooting some identical shots ect, but wondered if someone could give me some heads up.
Thanks p.

 

[Alan9940]

N- development brings down the high values, while one stop less exposure affects the shadow areas. For example, let's say you want important shadow detail in Zone III, if you underexpose by 1 stop that area is now in Zone II. If you place that same shadow area in Zone III, but your high values fall into Zone IX, then if you do an N-1 development those shadows will still be in Zone III while the high values will now be in Zone VIII.

 

[Doremus Scudder]

Let me add to Alan's reply:

Underexposing by one stop shifts every value that the film records down by the same amount. Anything that was one stop above the film's exposure threshold when exposed correctly (i.e., low shadow values) will now not record on the film at all. There's no retrieving what doesn't record on the film. Underexposure = loss of shadow detail, period. All the other values on an underexposed negative, including the highlights, will be moved down one stop as well, reducing the overall contrast on the negative. If the scene has a small subject brightness range (SBR) and the neg is developed "normally," the resulting negative will need a high-contrast setting to be printed if it can be printed well at all. If the scene's SBR is normal, the neg may print well at a higher contrast setting, but the shadows will be sacrificed. A scene with high SBR and normal development will yield a negative with the right contrast range to print well at a medium contrast setting, but the shadows values will still be missing.

Now, take a negative exposed correctly (by this I mean that it delivers the detail in the shadows that the photographer desires). If the subject brightness range is "normal" and the development is "normal," then the negative will print easily at a medium contrast setting giving both good shadow detail and nice highlights. If the SBR is large, however, and you develop normally, the neg will need a really low contrast setting to get both shadows and highlights to print well. Often, the SBR is so large that normal development results in a negative that simply can't be printed well, even at the lowest contrast setting. The answer is to develop the negative less. We expose fully so as to keep the shadow detail, but develop the negative less so that the highlights aren't as far away from the shadows contrast-wise. Developing less affects the shadows only slightly, but has a greater effect with more exposure, meaning that the highlights will end up being developed much less in relation to the shadows. The resulting negative then can be more easily printed at a medium contrast setting.

This basic concept gets turned the other way for N+ developments.

Hope that makes sense,

Doremus

 

[Andrew O'Neill]

Minus development affects the contrast (slope of the curve)... minus exposure shifts the film curve to the left...slope of the curve (contrast) remains the same if normal development is given.

 

[BSP]

OMG! I finally get it!

Thanks Doremus, AlanH and PeterK.

 

[CMoore]

I wish i shot some type of sheet film, just so i could (easily) try all of this stuff.

 

[Ariston]

Adams' "The Negative" explains this very well, with more detail on other techniques, if you want to pick up a copy. They are cheap these days..

 

[CMoore]

Yeah i have..... Cam, Neg, Print. Those hard-backs with the gray covers.
But they are still in boxes as our house move is taking longer (Big Surprise) than we anticipated.
I will definitely be looking at mine (again) in the near future.

A young person in my photo class was asking me about those books.
I was telling her that YES, A Lot/Some of it might be over hear head (and mine) right now, but it starts to fall into place as you progress.
Plus, it is also a great reference trio..... not something you just read one time.
Like a lot of books.

Thanks for the reminder

 

[138S]

I would add that ISO speed rating (box speed) states a fixed latitude of 3.3 stops in the shadows, if you underexpose 1 stop you only have a latitude of 2.3 stops in the shadows and you have 1 additional latitude stop for the highlights.

ISO speed norm says at -3.3 stops (underexposure) density is 0.1D plus fog+base. N-1 development, as other said, modifies negative contrast.

Expose for the shadows and develop for the highlights. You expose enough for having detail in the shadows in what you want detail. Later you develop to not blow the highlights exposed with that exposure that allowed to record detail in the shadows. With rolls we make same development for all the shots in the roll, with sheets we may make a custom development for each individual shot.

 

[peter k.]

Oh that was great, .. thanks all, .. especially Alan and Doremus that cleared it up..

 

[Bill Burk]

I wish i shot some type of sheet film, just so i could (easily) try all of this stuff.

Just shoot whole rolls of one kind of situation. All indoors by available light and develop it longer than normal, maybe five minutes longer than usual.
Then shoot another roll outside in bright daylight and develop it normally.
You don't have to shoot sheet film to learn about and take advantage of different developing plans. You just have to take some notes about how you shot a roll and commit that whole roll to one developing time.
Yes you can cut a roll in half if you really have to. I did that once and my guess was pretty close, I only cut one good picture in half and the next shot had the same people so I consider myself lucky.

 

[RalphLambrecht]

Curiosity question more than anything else.
Learning a new sheet film, Tmax 400, and developing it in different developers, Xtol, D-76 and Hc110 to see which we like the best. Shooting it at 400, to start with and using specifically to get started, the Kodak reference for temp and timings. Later on we will experiment, on different asa ratting, ect, ... but right now want to set the basics for my developing.
Noticed on a group, of same subject, that one shot was shot a stop underexposed, . and are liking the look of that one the best.
Which somehow raised the question, what is the difference in result in exposing and then developing n-1 vrs exposing one step less in exposure and developing for the normal time?
The only thing we could come up with is that with n-1 developing you would have more control as the timing is flexible vrs a 1 stop underexposure is very set.
What would be the difference? I suppose we could get educated and test this by shooting some identical shots ect, but wondered if someone could give me some heads up.
Thanks p.

Bill, a typical N-1 treatment is a1/2-2/3 stop overexposure and slightly reduce3d development time, which would give you a reduced negative contrast and richer shadow3sunder exposing by one stop with normal development is pretty much the opposite of that.

 

[138S]

a typical N-1 treatment is a1/2-2/3 stop overexposure and slightly reduced development time,

Ralph, I'd like to ask you why do you consider that a typical N-1 is 1/2-2/3 overexposure and not the nominal 1 stop overexposure and acording development. Just asking advice about nomeclature, may we say N-2/3 for that ?

Thanks in advance.

 

[CMoore]

Just shoot whole rolls of one kind of situation. All indoors by available light and develop it longer than normal, maybe five minutes longer than usual.
Then shoot another roll outside in bright daylight and develop it normally.
You don't have to shoot sheet film to learn about and take advantage of different developing plans. You just have to take some notes about how you shot a roll and commit that whole roll to one developing time.
Yes you can cut a roll in half if you really have to. I did that once and my guess was pretty close, I only cut one good picture in half and the next shot had the same people so I consider myself lucky.

True enough..... and there is nothing like seeing the results for "Yourself".
For a beginner like me, it would probably be well worth the effort.
Thank You

 

[Doremus Scudder]

Ralph, I'd like to ask you why do you consider that a typical N-1 is 1/2-2/3 overexposure and not the nominal 1 stop overexposure and according development. Just asking advice about nomenclature, may we say N-2/3 for that ?

Thanks in advance.

I'll take a shot at a possible reason for Ralph's post:

First, in Zone System parlance, you don't "overexpose" for N-1 or any other contraction. There isn't a "nominal 1 stop overexposure" at all, rather, a shadow value is metered, placed in the desired Zone (e.g., Zone III) and then the highlights are measured to determine what development scheme is needed, e.g., N-1 or whatever. No "overexposure" or "underexposure" is in the mix.

Ralph is not talking about metering and placing shadows here, or aiming to get the Zone IX value down to Zone VIII (i.e., moving the highlight value one Zone or one stop), but rather compensating for the loss in effective film speed when reducing development from normal. The simple version of the Zone System often ignores the changes in film speed that happen with different developments and simply states that for N-1, one just meters normally, places the shadow value in Zone III and then chooses an N-1 development time to rein in the contrast. In a perfect world where effective film speed does not change with changes in development time, this would work just fine.

However, E.I. does change with different developments and, in the case of contractions, underexposure will result if we just use the meter reading for our "Normal" E.I. So, when planning N- developments, we have to adjust our exposure a bit to compensate for this loss of speed. I simply apply that like I would a filter factor, e.g., N-1 needs 1/3 stop more exposure than my meter reads when set to the E.I. for normal. AA talked about "supporting the shadows" when planning minus developments, code for giving more exposure than the meter reads (for normal). Some just come up with individual E.I.s for each development scheme. Whatever works.

Increasing development time speeds film up a bit, but we often just ignore the potential to change E.I. here because the slight overexposure doesn't have a detrimental effect on the negative like underexposure would. Still, for the few times I need N+2, I'll reduce exposure by 2/3 stop or more just to keep the neg from being too dense.

BTW, I'll often indicate an intermediate development, e.g., N+1/2 or whatever, since I can easily split the difference in development time between N and N+1 when developing sheet film in a tray. It's probably overkill, since a half Zone could easily be compensated for by contrast controls when printing. Still, I persist. I believe that BTZS is even more precise. Note that this applies to development times, not exposure.

Hope this helps,

Doremus

 

[138S]

N-1 or any other contraction.

Doremus, lets say that we use TMY with Xtol (stock), let's supose that MDC is correct and Normal would be 6.5min development that it would deliver 0.62 CI, metering on our subject that is like a grey card.

What is N-1? it is overexposing 1 stop and developing 5.75min ? (time given for EI 200)

https://www.digitaltruth.com/devcha...per=%Xtol%&mdc=Search&TempUnits=C&TimeUnits=D

If not, how do we calculate N-1 development time and exposure?

 

[Bill Burk]

Doremus, lets say that we use TMY with Xtol (stock), let's supose that MDC is correct and Normal would be 6.5min development that it would deliver 0.62 CI, metering on our subject that is like a grey card.

What is N-1? it is overexposing 1 stop and developing 5.75min ? (time given for EI 200)

https://www.digitaltruth.com/devchart.php?Film=%Kodak+TMax+400%&Developer=%Xtol%&mdc=Search&TempUnits=C&TimeUnits=D

If not, how do we calculate N-1 development time and exposure?

Not at all but don’t fret. It’s just something different than you’re thinking.

N for Normal is Zone System nomenclature, when your contrast between important tones ranges from about Zone II to Zone VIII. The Zone System traditionally has you test everything from the contrast differences in your light meter readings to camera shutter, film and enlarger and print... so there aren’t charts you can turn to (but people can share their results of testing to give you an idea what you might expect).

While massive dev chart is telling times for normal, push and pull developing only considering exposure differences.

N-1 is for the situation where you placed your shadow on Zone II (or Zone III) and also have important tones metered at Zone IX (or Zone X the practice is a bit fuzzy on where exactly you call for N-1).

Basically it’s the situation where there’s one stop more contrast than Normal so you develop less to keep the negative fit to Grade 2 paper.

 

[peter k.]

typical N-1 treatment is a 1/2-2/3 stop overexposure and slightly reduced development time

and ..

So, when planning N- developments, we have to adjust our exposure a bit to compensate for this loss of speed. I simply apply that like I would a filter factor, e.g., N-1 needs 1/3 stop more exposure than my meter reads when set to the E.I. for normal.

By golly gonna have to experiment with this. Do not do much N - or + development, and somehow when we have with N-, forgot all about in increasing the exposure a little. But your comments brought that back to light. Thanks...

 

[138S]

Basically it’s the situation where there’s one stop more contrast than Normal so you develop less to keep the negative fit to Grade 2 paper.

Bill, by overexposing 1 stop we don't modify contrast: we still have the same sensitometric curve of 0.62 CI (0.62 if following developing recommendations in the film datasheet). This is seen when we overexpose one or two stops TMX and we still print with the same paper grade, we of course require longer exposure times for the paper but the resulting print it's the same with same paper grade.

When we overexpose one stop then we have one stop more latitude in the shadows and higher densities in the highlights, to not have excessive densities in the highlights then we may decrease CI with a shorter development, having a larger latitude in the highlights before we reach insanely high densities or blowing highlight detail (in D100...), but when we make a N-1 we always require a higher paper grade, as we have a lower gradient from the compression of the shorter development.

... but probably we have a different behaviour if using a linear film vs using a S curve film. A classic type S film modifies more the effective tonal curve in the scene because the same scene spot is placed in different regions of the curve with more or less local CI.

Please correct me if I'm wrong

 

[Bill Burk]

138S,

You are right that increasing exposure doesn’t change the contrast.

But don’t put too much emphasis on 0.62 I don’t know if manufacturers’ standard times are for 0.62 CI - that is ASA specifications for testing for sure but unless you see 0.62 on the data sheet, they may be giving you a practical time with a lower aim. In Zone System the N normal CI is a little lower - Something like 0.55 CI

When you figure out N-1 development times, you are trying to shorten development just enough that you keep the paper grade the same when the subject luminance range is just one stop longer than Normal.

 

[138S]

But don’t put too much emphasis on 0.62 I don’t know if manufacturers’ standard times are for 0.62 CI - that is ASA specifications for testing for sure but unless you see 0.62 on the data sheet, they may be giving you a practical time with a lower aim.

Bill, current norms say ISO test can be done with any developer, and developer/processing should be stated in the ISO rating, but CI for finding the speed point has to be 0.62.

In my experince Kodak/Ilford/Fuji state developer/times in datasheet aiming 0.62 CI which is also the mandatory CI for calculating the ISO, other manufacturers like Foma IMHO have a more "elastic" wording in datasheets, but in the Kodak and Fuji cases the exposure scale in graphs are in absolute Lux*Seconds, so technically they specify very well what film does.

In Zone System the N normal CI is a little lower - Something like 0.55 CI

I guess that CI is bit elastic in ZS, negative contrast has to allow to "print easily in grade 2 paper", so CI will depend on if our enlarger is condenser or diffuser, on what "kind of Grade 2" our paper has, on our paper developer, on toning or not the Grade 2 paper, on our taste...

Additionally all the Zone System has a big mess with exposure since the film speed change that happened in mid XX century when the 1 stop safety factor was removed, some say that we have to meter for Z-VI and not for Z-V, some say that antique Z-II is now Z-III...

I guess that at the 0.55 you point is good advice, what I don't know is how/where that 0.55 is stated. We know for sure that 0.62 is the CI used for ISO speed calibration.

Perhaps the right CI for ZS depends on each film, what happens in Z-II and in Z-VIII depends on how toe and shoulder are placed in the sensitometric curve. A pronounced S shape in the curve would command a lower CI to match the zones, while a less pronounced S should command a higher CI. Perhaps for this reason they say "it has to print easy in Grade 2", and find yourself what CI is is the good one.

 

[Doremus Scudder]

Doremus, lets say that we use TMY with Xtol (stock), let's supose that MDC is correct and Normal would be 6.5min development that it would deliver 0.62 CI, metering on our subject that is like a grey card.

What is N-1? it is overexposing 1 stop and developing 5.75min ? (time given for EI 200)

https://www.digitaltruth.com/devchart.php?Film=%Kodak+TMax+400%&Developer=%Xtol%&mdc=Search&TempUnits=C&TimeUnits=D

If not, how do we calculate N-1 development time and exposure?

The discrepancy you describe comes from the different metering techniques. Metering a grey card and basing exposure on it is similar to average metering in that you are basing your exposure on the lighting for middle value (that hopefully your meter is calibrated to...).

The Zone System assumes that exposures are based on a shadow value. When you base your exposure on the lowest important shadow value in a scene and place that in Zone II or III, then your exposure will not change much, if at all, with different developments.
One simply meters the chosen shadow, places it appropriately and then checks to see where the highlight values fall. Development is then based on where the highlights fall. If they fall just right (Zone VIII for a textured high value), then we develop normally (N). If the highlight we want textured falls too high, say Zone IX, then we need to bring it down to Zone VIII to print well. So we reduce development appropriately (N-1). Note that we don't really change our base exposure from our base shadow value; we might have to compensate slightly for the film speed change with a reduced development, but we aren't "overexposing" anything. The opposite happens when the highlight falls too low (say our desired Zone VIII falls on Zone VII). Then we increase development time (N+1). We can compensate for the slight increase in film speed with the longer development too if we like, but we're not "underexposing" from the basic meter reading of the shadow.

If you are basing your exposure on a midtone (grey card or the like) or higher value (like a light skin tone) or using a camera with a built-in averaging meter, then you are no longer basing your exposure on a shadow value and will have to do some exposure compensation. The formula, "overexpose one stop and develop N-1" is an approximation used often in this scenario, but note that it is not nearly as accurate at ensuring adequate shadow exposure as really metering a shadow value and using that.

The old saying, "expose for the shadows, develop for the highlights" applies to what I'm describing, and assumes that exposure is being determined from the shadow value.
If you "expose for the midtones, ..." then you have to "overexpose" from the meter reading when scenes are too contrasty to ensure that the shadows don't get lost. I do this when using roll film and a built-in meter, but I don't usually "underdevelop." Rather, I just print at a less-contrasty paper grade. I don't consider this using the Zone System either... If you have an entire roll shot under one lighting condition, then certainly you can tailor your development for whatever the subject brightness range is, but with many different kinds of lighting on one roll, you need to have a good average "Normal" development time that allows the extremes to fall within the range of contrasts available during printing.

"Pulling" film for better shadow detail is just overexposing from the box speed and developing normally, and will, indeed, get more shadow detail. It may even be necessary with certain cameras and meters just to get the film properly exposed. Better is to find a personal E.I. for your equipment and use that ensure you get good shadow detail.
Pulling and underdeveloping is similar to (but not as precise as) a Zone-System-style contraction (N-) development. It is for use in contrasty scenes with a larger-than-normal subject brightness range. Underdeveloping a "normal" scene will just give you a flatter negative that you'll need a higher contrast paper grade for.

Hope that explains things,

Doremus

 

[Doremus Scudder]

Bill, current norms say ISO test can be done with any developer, and developer/processing should be stated in the ISO rating, but CI for finding the speed point has to be 0.62.

In my experince Kodak/Ilford/Fuji state developer/times in datasheet aiming 0.62 CI which is also the mandatory CI for calculating the ISO, other manufacturers like Foma IMHO have a more "elastic" wording in datasheets, but in the Kodak and Fuji cases the exposure scale in graphs are in absolute Lux*Seconds, so technically they specify very well what film does.

I guess that CI is bit elastic in ZS, negative contrast has to allow to "print easily in grade 2 paper", so CI will depend on if our enlarger is condenser or diffuser, on what "kind of Grade 2" our paper has, on our paper developer, on toning or not the Grade 2 paper, on our taste...

138S,

We really need to disambiguate the word "contrast." For sensitometry, it is the rate that density changes proportional to exposure. In colloquial parlance, however, we mean the relative distance between darkest and lightest values in a scene or print. A "high-contrast" scene may be better described as a scene with a large subject brightness range, but we don't always do that. We get into murky territory when speaking of a "contrasty" or a "flat" negative. We should be able to, however, understand that it is the range of tones on the negative and not the contrast index that is being referred to here.

Yes, the ISO standard CI is important. However, for really contrasty scenes or really flat ones (see what I'm doing...), we need to tweak that CI in order to get a negative with a contrast range from low to high that matches the contrast range of a normal scene developed normally in order to have it print well at our chosen mid-grade paper (or filter setting). N- developments, or contractions lower the CI while N+ (expansion) development increases it. All this to get the range of tones on the negative to match the paper we've chosen.

Sure, you can develop everything to a CI of 0.62 and use controls at the printing stage. That works well if your negative contrast range can be accommodated by your print materials. For extremes, however, this is often not the case. Plus, some of us like the way a certain VC paper responds at a particular contrast setting better than the rest (I like MCC-110 at about 90-140 M on my color head for instance), so we develop to get a negative with a contrast range that prints well at that setting.

And, yes, it depends on if the enlarger is condenser or diffuser, what the coating is on your lenses, etc., etc. Keep in mind, however, we're really only trying to target a one-zone-wide window and eliminate the PITA of printing negs that are extremely contrasty or flat.

Additionally all the Zone System has a big mess with exposure since the film speed change that happened in mid XX century when the 1 stop safety factor was removed, some say that we have to meter for Z-VI and not for Z-V, some say that antique Z-II is now Z-III ...

Perhaps the right CI for ZS depends on each film, what happens in Z-II and in Z-VIII depends on how toe and shoulder are placed in the sensitometric curve. A pronounced S shape in the curve would command a lower CI to match the zones, while a less pronounced S should command a higher CI. Perhaps for this reason they say "it has to print easy in Grade 2", and find yourself what CI is is the good one.

The change in film speed determination really has no effect on modern Zone System users. We simply calibrate and determine our own E.I.s and development times. These we base on a particular set of parameters that include a specific film, developer, meter, enlarger, paper, paper developer, etc., etc. Some of these make more or less difference and can be safely interchanged (print developers, for instance). Other changes demand a new calibration (a different film, for instance).

Furthermore, most ZS users base their E.I.s on a lower shadow value (ZII or ZIII), not the speed point of the film. It's the final result that counts (shadow detail), not establishing norms for a particular material. Keep in mind that the Zone System is not precise sensitometry; it is a practical application of sensitometry that allows easy, repeatable and precise-enough determination of exposure and development for photographers in the field. The exposure determination is not as precise as it could be, but it gets us consistently in that one-zone sweet spot so we can more easily print our work. Of course, we use contrast controls at the printing stage as well, but, hopefully, more effectively and with less "saving" of bad negatives and more emphasis on expressiveness.

Best,

Doremus

 

[138S]

The change in film speed determination really has no effect on modern Zone System users. We simply calibrate and determine our own E.I.s and development times. These we base on a particular set of parameters that include a specific film, developer, meter, enlarger, paper, paper developer, etc., etc. Some of these make more or less difference and can be safely interchanged (print developers, for instance). Other changes demand a new calibration (a different film, for instance).

Doremus, I guess that what I've quoted from your post it's the key concept. Just knowing at what underexposure we preserve detail, and knowing how to develop to not blow highlights. As usual we end in the "expose for the shadows and develop for highlights".

 

[Doremus Scudder]

Doremus, I guess that what I've quoted from your post it's the key concept. Just knowing at what underexposure we preserve detail, and knowing how to develop to not blow highlights. As usual we end in the "expose for the shadows and develop for highlights".

Yeah. I used to do a lot of testing to nail down my personal E.I., but now rely more on critical examination of my negatives and keeping good notes on exposure. And, I err on the side of overexposure if in doubt.

Really, what we're after is the minimum exposure to give us the detail we want in the shadow areas. If we get the detail we want, then there's no "underexposure" going on. This gets really personal. Sure, there are ISO standards for film speed, but creative processes rarely adhere strictly to such standards. I'm not advocating sloppiness; I often simply want a different look (more shadow detail, more dynamic range) in my work than the norms will get me so I'll go with more exposure and less development. Some like black, empty shadows and a grittier, "pushed" look, so they'll expose less and develop more.

Best,

Doremus