calibrating N+

[Wayne]

I'm looking for a good written description of how to calibrate my N+ development times based on visual (ie non-sensitometric) feedback. After working out my film speed and normal development times this way I think I can figure it out on my own, but I would still like a good written description so I dont overlook anything. Where can I find it?

Roughly what % increase in time over normal should I expect for N+1 with Ilford films, esp FP4+? 30%? 50%?

Wayne

 

[Donald Miller]

The only accurate way to do what you are wanting to do is to determine the exposure scale of the paper that you are printing on at the grade(s) that you want to utilize. This is obtained by taking a measurement of the reflection densities of the paper exposed to a step wedge at the respective grade(s).

After determining the paper characteristics, next determinine the varying development times for the film that you are choosing to use and by measuring the reflection density of the respective step wedge exposed film(s)to plot the curves of the film. Once this is done, you will have knowledge of the papeer and knowledge of the film and how they will respond when subjected to alterations departing from the norm.

Every other approach is subject to failures of transferable data in one form or another.

Or you can do what others think that they accomplish when they add percentages of development time and be somewhere in the same universe.

 

[smieglitz]

As Donald has said you need to determine the exposure scale of the paper first. However, you can do this visually by printing out a $9 Stouffer transmission density stepwedge and just eyeballing the tones.

Each step is approximately 0.15 density units (with the first step representing the base being about 0.05). So, exposing a film normally and compare the visual printed densities you get from the film to those of the printed stepwedge. To do N+1, you need to expose and develop the film so that the target tone/zone exposure moves up the scale and prints two steps lighter (2 x 0.15 = 0.30 density or one full stop loss in transmission).

Of course, you need to decide which exposure/zone you are aiming to shift. Do you want to call zone VII to VIII N=1, or zone VI to VII? V to VI?

In any event you can do this quite accurately with just a stepwedge. No need for co$tly tran$mi$$ion or reflection den$itometer$. They just make testing a little easier since you could do this by the numbers once you know the paper exposure scale..

Joe

 

[noseoil]

To determine the paper's characteristics, use the same grade of paper and don't deviate with respect to developer, temperature or time. Don't change contrast filters, grades or any other variables. Get the printed stouffer strip which shows zones 1-9. Determine which values you need for a "normal" rendition of tones (for example, I use zones 3-7 as the limits of fully textured tonality). Use a scene of known values. Take the shot and develop so that 3 is 3 and 7 is 7. Once this is done, you will need to change development to allow for increased and decreased contrast.

This will limit you to a single, film, developer and paper, but it will also allow you to do what you want without the cost (in money) of a densitometer. Your trade-off will be in terms of time, film, paper and wasted materials. If you will take the time to read up on SBR numbers, your system will fall into place pretty rapidly. Remember, you need a standard against which to work. If you don't have a known zone strip which is close, the time and effort will be wasted. While the scientific approach is the best, there are other methods which can work. tim

P.S. Talking to someone about density units is not answering the question. It is meerly an added layer of confusion, although it is the correct layer.

 

[maxby]

Sorry for the OT. Can you let me know where I can get this "$9 Stouffer transmission density stepwedge"? Thanks

 

[smieglitz]

Sorry for the OT. Can you let me know where I can get this "$9 Stouffer transmission density stepwedge"? Thanks

Bostick and Sullivan sells them (check the APUG sponsors for the web address) and you may be able to find them at a local grphics arts supplier.

Joe

 

[Allen Friday]

Wayne,

In your post, you asked for a written source describing how to determine N+ development. The first two responses were from adherents to the BTZS school of photography. While the system is very good--I use it for all my initial testing-- it is not the only system that will give you good, repeatable results.

Your question shows that you are using or are interested in using the Zone System. Photographers have used it with good results for 50 years. If you don't want to buy a densitometer and go the BTZS route, don't. Just learn the Zone System.

The best book I have found for learning the ZS is "The Practical Zone System" by Johnston. It lays out the testing proceedures in a very straight forward manner. It is also very well written and easy to follow. Much better than Ansel Adam's book, "The Negative." Buy it and follow the testing steps for your n, n- and n+ development on your chosen paper.

 

[smieglitz]

Wayne,

... The first two responses were from adherents to the BTZS school of photography...

Not so in my case.

Joe

 

[Allen Friday]

Sorry Joe, my mistake.

Allen

 

[Wayne]

As Donald has said you need to determine the exposure scale of the paper first. However, you can do this visually by printing out a $9 Stouffer transmission density stepwedge and just eyeballing the tones.

Each step is approximately 0.15 density units (with the first step representing the base being about 0.05). So, exposing a film normally and compare the visual printed densities you get from the film to those of the printed stepwedge. To do N+1, you need to expose and develop the film so that the target tone/zone exposure moves up the scale and prints two steps lighter (2 x 0.15 = 0.30 density or one full stop loss in transmission).

Of course, you need to decide which exposure/zone you are aiming to shift. Do you want to call zone VII to VIII N=1, or zone VI to VII? V to VI?

In any event you can do this quite accurately with just a stepwedge. No need for co$tly tran$mi$$ion or reflection den$itometer$. They just make testing a little easier since you could do this by the numbers once you know the paper exposure scale..

Joe

argg, firefox closed on me and deleted my long reply so here is my short one.

I think this will give me what I want. What's scarier, I think I even understand it. I do have a step wedge already. In making this comparison, do I have to expose/print the step wedge a particular way, or just use any old exposure with my normal development routine? I suppose the exposure doesnt matter as long as I get enough distinct steps to make the comaparison

I am looking primarily to determine a V->VI or VI->VII development at this time.

Wont I need to adjust my film speed when I know I'm going to N+, and if so how do I determine that?

BTW, I was just curious what % increase other people have found with Ilford films, as a reference to "bracket" when I do my tests. I wasnt looking to adopt anyone else's numbers.


Wayne

 

[noseoil]

Wayne, if your film speed is pretty close already, you just need to determine how much more development time is necessary. We are splitting hairs here when it isn't really necessary. If you already have decent shadow values, increased development won't hurt them at all. To pick a number out of thin air (sorry, use efke not ilford) I would try 10%, 20% and 30% as your points of departure. This will give you a range of vlaues, one of which should be very close. Remember, it is the print value we want, not the density number in mathematical terms of density, opacity or anything else.

The reason I mentioned BTZS type exposure numbers is their ability to give a 1:1 plot of development times with respect to scene brightness for a good print. This will only work for one film, paper & developer combination, but it will work. The SBR number for exposure is simply the highlight value minus the shadow value, added to 5 (the paper's range). Let's say you have a scene in which your highlights fall on ev 15 and shadows fall on ev 11. 15 - 11 = 4, so now you would just add 4 + 5 to get an SBR number or 9. This is your SBR number for the shot. If you don't have a spot meter, just use whatever meter you have and get a highlight reading. Do the same thing with shadows and count the number of stops between high and low values. This is the range of values you have to work with in light.

Get a peice of graph paper and on the left side (x-axis) mark SBR numbers from 5 to 12 in 1/2" increments, 5 being closest to the bottom, 12 being at the top. Do the same thing on the bottom (y-axis) with time. Use increments which are marked each half inch with short times being at the left (closest to the x-axis), go from 5 minutes out to the right as far as you can.

Draw a faint horizontal line from the left on the x-axis at SBR 9. Do your development tests to determine the correct time for this SBR 9 number and mark it on the lower (y-axis) at the corresponding time. Where the SBR 9 meets the time for your known print value of time, you have a correct development time. If you will keep track of SBR numbers and development times, a "curve" will be the result which can then be drawn in with a french curve. This is all there is to the whole business. Once you have a plot of this curve, record the SBR for each scene. Decide how much contrast is necessary for the print and stay with the development time.

Even if your eyeball is off a bit, the plot of a line through these points is the average of all of the times. Close enough for what we need to get a decent print. Best, tim

P.S. If you have any questions about this plotting business, please pm me off list.
P.P.S. Apologies to those BTZS people for my mutilation of Phil's studies.

 

[Allen Friday]

Dear Wayne,

In your first post you asked for a written source for determining N+ development. I gave you my recommendation above. It now seems that you have changed your mind and want to follow the steps laid out by people here on APUG. So, I will throw out my two cents worth on how to do this in traditional zone system terms.

You state that you already have determined your film speed and N development times. Presumably, you have done the initial testing to determine this. So, you should have a standard printing time. Also, you should have prints of the zones on your paper for normal times. Somewhere you should have a print of a negative that is Zone V, one that is Zone VI, and one that is Zone VII. In other words, you have already determined your papers “exposure scale” based on your zone tests. Now all you need to do is modify development of the negative to bump Zone VI to Zone VII. This can be done by exposing and developing three negatives.

To determine your N+ development, make three exposures of an evenly lit surface, preferably one near a mid tone, at one stop more than the meter reading (Zone VI). Develop one 10 percent longer, one 20 percent longer, and one 30 percent longer than your N time. Print the three negs at your standard printing time. Once dry, compare the three extended development prints to the control Zone VII print you made in you initial tests. One of them should be pretty close. Say the print from the neg developed 20 percent more is close, but a little light. Then you know that you will have to back off development a little, to say 18 percent. If the control neg is right between the 10 and 20 percent print, then you know you need to go to 15 percent increased development.

If you are shooting sheet film, this is easily accomplished. On roll film, just shoot a whole roll at Zone VI and then cut the roll into pieces for the different development times. Albeit, developing less than a full roll will throw off the result a bit, it should not be terribly significant.

Once you have your N+ time with in a percent or two , you can fine tune it using real negs--i.e. field testing.

 

[Wayne]

Dear Wayne,

In your first post you asked for a written source for determining N+ development. I gave you my recommendation above. It now seems that you have changed your mind and want to follow the steps laid out by people here on APUG.

I'm not sure why you say that. Has my confusion confused you into thinking that I know something that I dont? I was going to reply to several responses as part of my reply that was devoured by Firefox, but that all changed when I had to start all over. I actually had the book you recommended checked out a few weeks ago, and I skimmed it, but I had already started my basic testing and didnt want to start over so I didnt read it thoroughly. At the time I was only trying to get the basics tested. I determined my film speed, N time, and maximum black time using Picker's Zone VI Workshop and a recent Simmons article in VC (which are both variations of the same thing). I made prints of Zone I and VIII in these tests, but not those in between. But thats easily enough done.

Question: should I expect a significant difference in N+ time if I want to bump a V to VI versus a VI to a VII?

Question: How much expansion (or contraction for that matter, though I'm not there yet) can I hope for with FP4+ and HP5+?

Referring back to the film speed when N+/-ing, I was probably thinking of Adams saying "less exposure is needed to reach the threshhold than with N development. It is often possible to place the shadows one-half zone lower than normal, esp when attempting greater than N+1...". And he basically says the opposite for contraction. So I dont need to do this, if I understand noseoil right?

Thanks for the explanation. I think this will be simple enough for my simple brain, and is pretty much what I would have done if I hadnt asked the question, but its good to have it in writing. I guess I'm starting to get less confused.


wayne

 

[smieglitz]

What Allen said.

...
Question: should I expect a significant difference in N+ time if I want to bump a V to VI versus a VI to a VII?

Exposure affects the shadows but development doesn't to any significant degree. The further up the scale you get from the shadow zones, the greater the effects of development. So, midtones are affected by development to a much greater degree than shadows, and highlights are significantly affected by development relative to midtones (and shadows). To get from V to VI will take more development change than to get from VI to VII. How much change (i.e., what is a "significant" change) depends on the formula of the developer, film type, dilution, etc. You will just have to test for it, but your visualization of the other zones shifting will depend on what you call N+.

Question: How much expansion (or contraction for that matter, though I'm not there yet) can I hope for with FP4+ and HP5+?

Modern films generally let you get to N+2 or perhaps a bit more. If you are looking for great expansion potential, you may wish to check out Efke 25 as well. For more options see the section on "Bi-directional contrast control" in "The New Zone System Manual" by White, Zakia, and Lorenz. There they talk of combining a visualization incorporating maybe N+2 film development with a contrast filter increase when printing to achieve N+3 or higher. That text is a hard read because of White's esoteric style, but it is probably the best book (IMO) when it comes to theoretically discussing visualization. For a more practical discussion see Ansel Adams' "Examples:The Making of 40 Photographs"

...
Referring back to the film speed when N+/-ing, I was probably thinking of Adams saying "less exposure is needed to reach the threshhold than with N development. It is often possible to place the shadows one-half zone lower than normal, esp when attempting greater than N+1...". And he basically says the opposite for contraction. So I dont need to do this, if I understand noseoil right?

Practically you can expect to gain about a third stop increase in film speed when expanding N+1 with development. For N+2 you might gain another third stop with diminishing returns beyond that point. Going the other way, you can expect to lose about a third stop for each minus development.

Joe

 

[smieglitz]

Quote: To get from V to VI will take more development change than to get from VI to VII.


I am not sure that I can verify this statement under actual objective testing.

You could try.

...For instance, if a film has the Zones that the Zone system speaks about placed on the straight line portion of the H and D curve then a change in development will make as much change within the general region comprising Zone V to VI as it will from Zone VI to VII within .03 units of density difference between these arbitary separations.

Yes, on the same curve, but not between two different curves given different development treatments. I'll stand by my general statement (and previous experience testing) until shown evidence to the contrary. My statement:"How much change (i.e., what is a "significant" change) depends on..." is a qualifier. If you want to call the zone separations "arbritrary" and consider 0.03 insignificant (and BTW I believe the difference is actually greater though I don't have my plots in front of me at the moment to confirm this), you are being much more specific than I. I'm trying to provide as simple and as general an answer as I can to someone I believe is just beginning to explore these concepts and I'm intentionally avoiding being too specific, avoiding numbers wherever possible, and being too nit-picky. IMO your focus on exacting precision and sensitometric equipment is not on target here although it would certainly be valid in a more advanced discussion. "Horses for courses."

Furthermore if a film has a shoulder and the upper zones (your term, not mine) are on or approaching the shoulder then it would require more developmental changes to effect changes in this upper region then it would within that portion placed on the straight line.

Yes, but again look at the original question. I don't know of anyone who would consider N+ to be expanding zone VIII to IX or IX to X where things might be shouldering with a certain film. Do you? So, while your statement is true, it is extraneous to the discussion of practical N+ expansion IMO.

Joe

 

[Allen Friday]

Wayne,

I did not mean any offense in suggesting that the topic had shifted to doing the testing instead of suggesting books. I was hoping others would actually make a suggestion of sources for you. Sorry if I caused any offense.

In your last post above, you raise a couple of issues. I see where your problem originates--I pulled my copy of Picker’s book off the shelf and skimmed it. He basically only gives a bare bones description of the ZS and ends with determining N development. It’s a good start, however.

As for the difference in development between pushing Zone V to VI and pushing Zone VI to VII, I have no idea. I have never tested the difference. When I meter, except in unusual circumstances, I meter zone III to set my exposure and Zone VII to determine development. I move zones up or down to match Zone VII. I do this because Zones III and VII are the “texture” zones, the first and last zones which are fully textured in the print. To me they are the most significant Zones, and so I meter to them.

My guess is that the difference between pushing Zone V to Vi would be pretty small. I base this on my more complicated metering problems, where I will move the intermediate Zones around. Basically, I end up developing N+1 the same whether I am moving Zone VI to VII or Zone IV to V and I have never noticed it being a problem But, I have not actually tested it.

But, I would recommend metering for Zone VII. By doing so, you provide for the important highlight information to be fully textured in the print. If you meter for Zone VI, you risk the chance of pushing some important details into the non-textured zones.

As for FP4, I have never tested it. I did a BTZS test for HP5 last year. I can pull that data off my office computer tomorrow and provide it to you. But, the % increase will be developer specific. I was testing negs for platinum printing, so I used D-76 1:0. But, my tests might give you a starting point.

I did pull out my copy of “The Practical Zone System”. On pages 112 and following, Johnson provides development time charts for various films in different developers. Here are his results for FP4:

Developer ASA N N+
D-76 1:1 125 10 11
XTOL 1:1 125 9 12.5
Ilford ID-11 1:1 80 8.5 12
HC-110 B 80 5.5 7.5
T max 1:4 125 4.5 5.5


Here are his results for HP5:

Developer ASA N N+
D-76 1:1 320 8.5 12
XTOL 1:1 320 15 21
Ilford ID-11 1:1 320 9 12.5
HC-110 B 320 5.5 7.5
T max 1:4 400 5 6

As you can see, the changes are very dependent on which developer you are using.

I have no idea how much expansion you can get with FP4. I will try to look up the result for HP5 on my computer at the office. My data is specific to platinum prints, which have a very long tonal scale. But I think I can just plug a grade two ES into the software and get you a good idea of what to expect.
Hope that helps.

Allen

 

[Wayne]

Allen, no offense was taken. I just didnt understand the comment. No need to go to any further trouble, I think I have everything I need to take the next step now. Thanks.

Wayne