using a zone chart to determine PEI

[Chuck P.]

Zone V print density is not fixed in law.

Sorry for the long post, but....

No one is suggesting that it is as I can see it anyway. The graph showing two curves clearly indicates different "toe" densities to no detriment to the ability to achieve a full tonal range in the longer toe versus the very short toe film-----they were produced using standard ZS testing principles. And I've enjoyed good results from them. But they have obvious different "toe" responses to exposure and development as you can see. A long toe versus a short toe is only a different rendering of the low values in terms of contrast (shadows in a longer toed film will exhibit somewhat less contrast , but achieving a full scale is not affected as long as one has determined the personal EI by testing.

Both curves originate from the speed point (0.1 neg density at zone I) and cross the 1.3 "normal" development calibration line at Zone VIII, for my desired density range of 1.3 - 0.1 = 1.2. I was fortunate to get full box speed with D-76 1:1, no adjustment was needed. But I had to adjust the HC-110 curve and so provided the uncorrected curve to show how I did it. It's the same curve shape but it's a bit more stretched out on the page (due to the vertical axis going up to 2.5) than what is seen in the comparison curves (vertical axis goes to 2.0) .

The second graph showing the uncorrected curve shows that if I use the ISO of 100 with TMX and HC-110 (1:63), then I'm cheating the log exposure scale in the shadows by almost a full zone of print tonality. By correcting the curve for the desired speed point through a reduction of 2/3 off the box speed to EI64, I regain useful exposure between Zone I an II (easily seen in the comparison curve graph), thus maintaining complete scale in the shadows.

At the highlight end of the uncorrected curve, notice that the curve crosses the 1.3 density line at about Zone VIII 2/3 with an 11 minute development time. It was luck that after correcting for the speed point, the curve crossed the 1.3 line exactly at Zone VIII----easily giving me my "normal" development time of 11 minutes with TMX at an EI of 64. So, with one sheet of film I got the personal EI and "normal" development time, sometimes it works out that way. Usually, I would have to expose anther sheet to the step wedge at my new EI, then adjust the development time from the speed test to get the curve to cross the 1.3 line at Zone VIII, the lightest print tone that still shows some texture detail.

Anyway, your're suggesting that the curve shape (the liniarity or curvature of the toe) has something to do with being able to achieve a full scale of zones. I guess I would have to just disagree, and I doubt that I have proven anything to you. If one does not adjust the EI to get optimum log exposure, then he certainly would cheat himself of achieving a full scale in the shadows and if he does not calibrate "normal" development for optimum contrast in the highlights, he'll cheat himself there too. So, developing to a contrast range appropriate to the exposure scale of the paper will get a full scale print, that's my experience anyway, regardless of a longer toe or not. What matters, IMO, is taking full advantage of the available log expoure down to a useful lower density limit (0.1 above fb+f at Zone I), and then knowing at what upper density limit will print with contrast (Zone IX for very light tone, which should easily print Zone VIII for decent highlight texture) on the paper your're using.

Chuck

[percepts]

Your graphs illustrate perfectly what I said.

TMX in D76 giving neg density of 0.77 for zone V
TMX in HC110 giving neg density of 0.6 for zone V

They both have neg density of 0.1 for zone 1. But they would require different times to print the zone V at 0.7 print density because they have different zone V neg densities. But since they both have the same zone 1 density, printing them at different times would give you different zone 1 print densities which as you know, won't be right.

i.e printing zone 1 neg for print density and zone 9 for print density works. Printing zone V won't. Both ways will get you the range within your parameters but that wasn't the point. The point was that trying to use zone V as a print density check will lead you up the garden path to nowhere. Or as I said before, zone V is not fixed on print density 0.7 because if you try that you will not get zone 1 where it should be and correcting it by increasing print contrast will lose your shadow separation.

[Lachlan 717]

Tim,

Will you be printing or scanning?

Was your initial post only about setting your PEI?

[Tim Meisburger]

Hi Lachlan. It was only about determining EI and normal development, and I now think I have found a useful methodology here: http://www.paulwainwrightphotography..._your_eyes.pdf. He uses a transmission step wedge sandwiched over a negative, but it is essentially the same as shooting a reflective step or zone chart.

I am only interested in printing, not scanners, as I spend too much time at the computer already. Thanks to all for the help.

Best, Tim

[Chuck P.]

They both have neg density of 0.1 for zone 1. But they would require different times to print the zone V at 0.7 print density because they have different zone V neg densities.

Your're confusing "tone" with "contrast", IMO. The D-76 curve will have a higher local contrast than the HC-110 curve at Zone V but it's tone value if printing a gray scale would be the same.

[percepts]

Your're confusing "tone" with "contrast", IMO. The D-76 curve will have a higher local contrast than the HC-110 curve at Zone V but it's tone value if printing a gray scale would be the same.

Let me assure you I am not confused. You stated:

This is fine, but the enlarging exposure time is critical if your're to evaluate the efficiency of your Zone I and IX exposures, it must be based on a time used to print a middle gray value. To do that, a Zone V exposure is made, then printed so that its print value is matches the gray card. Use that enlarging time to print Zone I and the Zone IX negatives. This method is best if the target is a textured target, such as screen tightly secured to a uniform toned card.

from your charts if you take the d76 curve and print the zone V to give an 18% middle grey (0.7 print density) and use the zone 1 and 9 negs to print using the same time and they print as they should. i.e. just perceptibly lighter than max black and just perceptibly darker than zone X.
Then if you do the same with the hc110 zone V neg you will require a shorter print time and if you apply that shorter time to your zone 1 and zone 9 negs then you will get a zone 1 print value which is too light and a zone 9 print value which is too light. You have completely avoided explaining that.
I think you need to print some zone negs to verify that your zone negs actually print how you think they're supposed to because I can see from your charts that they won't both work as you seem to think they do. This is because you mistakenly beleive that zone V will always print as 18% middle grey. This is only true for a curve of one specific shape. It is not true for other curves of which there are many. i.e. Zone V print value is not a constant. So your assertion that zone V must be prinetd as print value 0.7 density (18% middle grey) is wrong or you accept that zone zone 1 and zone 9 don't print where they are supposed to.
Once again AA has misled one of his disciples. This is one of the anomalies of the zone system which confuse his disciples when they are confronted with it because they refuse to beleive that he published something which is not right.

[Ken Lee]

As Bruce pointed out, Fred Picker's Zone VI Workshop is very good.

Another fine book is The Negative by Ansel Adams.

Once you grasp the basics of development and exposure you might want to try the method recommended here.

[Chuck P.]

I think you need to print some zone negs to verify that your zone negs actually print how you think they're supposed to because I can see from your charts that they won't both work as you seem to think they do.

My previous post said that the tones would be the same, but they will actually vary slightly because of the curve shapes in the toe region that we are discussing and will even affect the upper zones. What will be consistent, at least after I performed this, is the tone of the Zone V negative. I'll try to explain.

After restating my thought from this morning, understand that I would not have said what I said if I had not already done this, years back, but you believe what you want. I know for a fact that a representative gray scale can be produced off of both those curves in the manner that I have suggested, I've done it. Others can try it but the adjustment for personal EI and calibrating "normal" development should be accurately done, if not you probably won't be pleased with the results, IMO. What will be consistent is the tone of the Zone V negative as it is based off matching it to the gray card in the ZS way of performing the gray scale------ even though the density is 0.75 for my d-76 curve or 0.6 for my hc-110 curve (yes, the exposure time on the paper will slightly vary, as it should). This will vary slightly the actual tone of the remaining respective zones while maintaining an accurate zone description.

Why? Because the tonal value associated with each zone is actually the mid-point shade of gray for that zone; there are slightly lighter and darker shades of gray on each side of the zones, other than the 0 and X of course. There is wiggle room for the actual tone that represents any single zone of the gray scale that can be printed with contrast, this can be clearly seen in a short toed film versus a longer toed film in zones I-III or IV. The exception being there is really no wiggle room for Zone V. In the ZS way of doing things (yes, I know it is not the only way, yes, I'm sure it has flaws, but not that I can see in the way that you are putting forth), printing Zone V to match the gray card fixes the entire tonal scale and any variation in curve shape does not adversely affect the validity of the gray scale produced.

I've tried not to take the tone that you have chosen, it's not worth it, I'll just end the discussion and you can believe what you wish about it without further input from me. Not meaning to sound preachy here, I'm just describing my results after having performed these things myself. I'm glad we have one thing in common though, we both love B&W photography, we can at least agree on that. It certainly is a passion isn't it?

[Stephen Benskin]

This is one of the anomalies of the zone system which confuse his disciples when they are confronted with it because they refuse to beleive that he published something which is not right.

If you want to nit-pick, you can almost find a mistake on every page of the negative. My suggestion is for people to read a book on photographic sensitometry. Adams is mistaken about film speed, what the meter reads, and the aim density range of the negative, among others. The Zone System is best when used for visualization. Adams says that it is a simple form of sensitometry. Why not go to a more authoritative sources for that part?

Percepts is absolutely right. The negative needs to fit the paper; therefore, you need to know what the log exposure range of the paper is before determining the negative density range. Otherwise, the NDR is arbitrary. Condenser enlargers will require a shorter NDR for the same paper than a diffusion enlarger. Printing on platinum paper requires a very different NDR. Even Adams had different ZIII densities for diffusion and condenser enlargers.

Interesting enough, the 1.20 negative density range probably isn't what you are actually getting in the field. Yes, it works, but not for the reasons Adams claims. The curves Chuck P plotted look like they are from contacting which has no flare (ZS in camera testing has minimum flare). The average scene (7 1/3 stops BTW) has approximately 1 1/3 stops flare. That will reduce the negative density range of the film. If anyone is familiar with the ISO LERs for paper, they should remember that a grade 2 paper has as it's midpoint a LER of 1.05. Why the discrepancy? One takes into account flare. The other doesn't. Instead of reading the negative density at VIII, we should be looking at the negative density at VII because we lose around a stop of apparent subject luminance range - 2.1 - .3 = 1.8. The negative density at VII in Chuck's graph is 1.05.

Finding the average gradient of the curve is the best way to determine your aim development. To determine the aim gradient you can use a simple equation - negative density range (as determined by the paper LER) divided by the subject luminance range minus flare.

ISO 1.05 / 2.2 - .40 = .58
ZS 1.20 / 2.1 - 0 = .57

They are effectively the same which means that for a given scene they will produce the same negative density range. So, how can they have different aim negative density ranges? Adams never explains how film and paper relate. He doesn't even match the same Zonal ranges between negative and paper. He has the scene Zones from I to VIII which is seven stops, but has ten Zones for the paper. My belief is that he based the print Zones on the Munsell scale which has ten steps and 18% at step 5 (and it predates the ZS by 40 years). Another big anomalies is with ZS speed testing, but that is a story for another time.

The shape of the curve of the film and paper also determine where the Zone Values fall. Except for a single tonal placement, it is not possible to be certain where anything will fall. And that is if Zones had a predetermined value which they don't. Again, a study of sensitometry would help clarify it all.

Steve

[Chuck P.]

The negative needs to fit the paper

I couldn't agree more. My negative fits my paper very well, I know because I print with it and I have two fine looking gray scales one for each curve and my negative density range is pretty dam consistent with regard to the density of a shadow placement or where a highlight falls on the curve, perfect no, but very much controlled and workable by me, yes. You can argue with Adams all you want to as I believe your ego craves that friction, but you can't convince me against my own results that I see with my own eyes, although you always try to . But you and I have sort of had these discussions before . I don't argue with what I have proven works for me, there's no need to when results speak for themselves, regardless of any real or perceived flaws in the system-----an excercise in futility if there ever was one.

Actually, the Zone VII density is 1.1 for d-76 curve and 1.02 for hc-110 curve, owing to the different curve shape of TMX with those developers and dilutions. Both produce a very nice Zone VII print tonality, albeit slightly different from each other, but more importantly, falling in line very nicely in tone progression on their respective scales relative to the curve from which they were produced. Now I just have no earthly reason to argue with that, but I appreciate your zeal anyway.

CP





Chuck