With 0.16 base+fog, how can I obtain 0.10 for Zone X?

Following the procedures in John P. Schaefer's, "The Ansel Adams Guide: Basic Techniques of Photography, Book 2", I have started testing Arista EDU 100 in 4x5.

Using my infrared goggles, I taped a 21 step Kodak wedge, emulsion to emulsion, diagonally across the surface of the sheet of 4x5 film.

Then, using a spot meter, I exposed the sheet +5 stops from the Zone V exposure measured off of a white poster board tacked to the shade side of my garden shed. The camera was focused at infinity and the card filled the frame totally. Measurements showed it to be 0.01 stop even across the entire span, so it was evenly illuminated.

Processing was in my Jobo 3006 Expert drum. Since I cannot obtain 68F/20C water from my pipes, I adjusted the time for D76 1:1 from 8:00 to 5:15, using the Ilford temperature adjustment chart for 72F/22.2C.

NOTE: I did not subtract %15 from this time, as some suggest; a lot of people simple ignore this "rule of thumb", so I decided to not shave even more time off the temperature adjusted result.

The processed film was dried and I measured the wedge with a Dektronics Printalizer densitometer to establish starting values. I then measured the processed film wedge copy values and plotted them on a Kodak Curve Plotting Graph Paper sheet.

Step 21 gave me 0.18d and Step 1 measured 1.43d with base+fog measuring 0.16. I used opaque black tape to attach the wedge to the film, so I had a good patch from which to measure actual base + fog...

Relative gamma measured between 0.55 and 0.60 gamma with Kodak Gammeter.

Questions and observations:

1. With a base + fog exceeding the desired 0.10 Zone X near Step 21, should I reduce the time even more? Already sketchy at 5:15 and afraid of getting streaking at lower times.

2. Since most B&W film stocks tend to rate UNDER their claimed ISO sensitivity, I have to wonder how Arista EDU, which most people de-rate by at least 1 stop, now is showing-up as being somewhat higher in sensitivity that its claimed 100 ISO. If I subtract the traditional 15% for continuous agitation, that's going to place me in the 4:30-4:45 region, which is kind of concerning. Of course, I did use a water stop to avoid depleting my TF5 fixer more rapidly, so some development may have continued beyond the programed 5:15 time entered into the Jobo. I have no desire to use an acid stop, so for now I hope to keep using a water stop.

Given the above, what would you suggest going forward?

It doesn't look bad and I am inclined to just "print through" the extra density rather than sweat this small detail...

I always take a reading of the base+fog with my densitometre, then zero it out first. In your case, step no. 17 is about 0.10 over base+fog. When I do this test, I always use 5 sheets of film. They are all exposed for the same time, under my enlarger, then each sheet is developed at various times. Curves are draw (manually, like yours), and then I can figure out my N times. Then I go out in the field with a few sheets, varying the ISO... almost always, the 2/3rd stop more sheets is my zone I (I use a scene that has Zone I, III, and VIII). There usually is a bit of tweaking between EI and dev times.

Andrew O'Neill said:

almost always, the 23rd stop more sheets

Click to expand...

@Andrew O'Neill ,
That is a lot of stops!
I'm thinking that you actually mean instead "almost always, the sheet with an additional 2/3 stop" .....

Kino said:

1. With a base + fog exceeding the desired 0.10 Zone X result, should I reduce the time even more?

Click to expand...

Hi, I'm not at all familiar with the book you referenced, but if you're concerned about the actual base + fog density this is mostly irrelevant. (Different film bases may have different densities, even with no emulsion.)

My guess is that the density value you are chasing is actually supposed to be ON TOP OF the base + fog. Similar to the way Andrew is doing it. Personally I would work with the actual density values, not zero the densitometer on the base + fog. But... whatever works for your purposes.

FWIW my understanding is that in Zone-System-speak Zone X gets MORE exposure, meaning that the step with barely exposed film is more like Zone I (but I'm not a Zone guy).

MattKing said:

@Andrew O'Neill ,
That is a lot of stops!
I'm thinking that you actually mean instead "almost always, the sheet with an additional 2/3 stop" .....

Click to expand...

Only if you're going for extremely dense negatives and flat contrast or a filter with a factor of 8,388,608X! I corrected it. Thanks!

By the way, The Ansel Adams Guide: Basic Techniques of Photography, Book 1, was the first book that I ever bought on photography. It's what pushed me into it...way back in '92. I also have Book 2...

Thank you Andrew and Mr. Bill.

I have been bouncing around between all the Zone System books I have (quite a few) to try to rationalize this process and the Schaefer book seemed to be the most straightforward and economical method.

Supposedly, you can expose 1 sheet per test and extrapolate future tests to establish N values and film speed from that first sheet, rather than burn 12 or more sheets of film initially, as in the majority of books on the subject.

As outlined above, it uses ambient outdoor light to expose the 21 step wedge to a single sheet of film at what should be the ideal exposure for the published ISO. A single exposure to a measured wedge made more sense to me rather than the increased variables in multiple sheets exposed at varying exposures.

I could have used an enlarger, but was concerned with the dissimilar spectrum quality between an enlarging lamp and the Sun. However, it seems to work fine for Andrew, so hmmm...

However, the book makes no provision for elevated B+F, which confused me. All of his samples are T-Max and Tri-X which have the 21st step reading in the 0.08d region.

Typically, we never subtracted B+F in our densitometry tests for motion picture work, but the aim points and application for these tests bore little relation to testing for Zone System manipulation. I am biased to keep the B+F in the calculation, but that is most likely just stubborn familiarity...

I don't want to start a running battle over subtract/don't subtract B+F, as in the past I have witnessed page after page of arguments here on Photrio for and against the practice which did not seem to change any participant's mind on the subject matter. As Mr. Bill says, "whatever works for your purposes."

Thanks for the input; I will have to give this a bit more thought as how to proceed.

Mr Bill said:

FWIW my understanding is that in Zone-System-speak Zone X gets MORE exposure, meaning that the step with barely exposed film is more like Zone I (but I'm not a Zone guy).

Click to expand...

Correct. I should have said "step 21" not Zone X! (and even that is not quite right).

Kino said:

Thank you Andrew and Mr. Bill.

I have been bouncing around between all the Zone System books I have (quite a few) to try to rationalize this process and the Schaefer book seemed to be the most straightforward and economical method.

Supposedly, you can expose 1 sheet per test and extrapolate future tests to establish N values and film speed from that first sheet, rather than burn 12 or more sheets of film initially, as in the majority of books on the subject.

As outlined above, it uses ambient outdoor light to expose the 21 step wedge to a single sheet of film at what should be the ideal exposure for the published ISO. A single exposure to a measured wedge made more sense to me rather than the increased variables in multiple sheets exposed at varying exposures.

I could have used an enlarger, but was concerned with the dissimilar spectrum quality between an enlarging lamp and the Sun. However, it seems to work fine for Andrew, so hmmm...

However, the book makes no provision for elevated B+F, which confused me. All of his samples are T-Max and Tri-X which have the 21st step reading in the 0.08d region.

Typically, we never subtracted B+F in our densitometry tests for motion picture work, but the aim points and application for these tests bore little relation to testing for Zone System manipulation. I am biased to keep the B+F in the calculation, but that is most likely just stubborn familiarity...

I don't want to start a running battle over subtract/don't subtract B+F, as in the past I have witnessed page after page of arguments here on Photrio for and against the practice which did not seem to change any participant's mind on the subject matter. As Mr. Bill says, "whatever works for your purposes."

Thanks for the input; I will have to give this a bit more thought as how to proceed.



Correct. I should have said "step 21" not Zone X! (and even that is not quite right).

Click to expand...

...and recently, I've even used my UV LED light box to expose slow films. Field tests confirmed that it's fine to use. Quicker exposure times, not having to worry about reciprocity effects.

It really shouldn’t make a difference whether or not you subtract base+fog. They are just plotting conventions. Typically Kodak, Ilford… plot gross density on the graphs, but net density is the same curve with the minimum density at 0 instead of B+F density. For ISO speed determination, Zone System etc. it’s always the differences in density over exposure ranges that matter.

Different formats have different base densities too, so if you really want to plot gross silver density you subtract the base only.

Kino said:

Thank you Andrew and Mr. Bill.

I have been bouncing around between all the Zone System books I have (quite a few) to try to rationalize this process and the Schaefer book seemed to be the most straightforward and economical method.

Supposedly, you can expose 1 sheet per test and extrapolate future tests to establish N values and film speed from that first sheet, rather than burn 12 or more sheets of film initially, as in the majority of books on the subject.

As outlined above, it uses ambient outdoor light to expose the 21 step wedge to a single sheet of film at what should be the ideal exposure for the published ISO. A single exposure to a measured wedge made more sense to me rather than the increased variables in multiple sheets exposed at varying exposures.

I could have used an enlarger, but was concerned with the dissimilar spectrum quality between an enlarging lamp and the Sun. However, it seems to work fine for Andrew, so hmmm...

However, the book makes no provision for elevated B+F, which confused me. All of his samples are T-Max and Tri-X which have the 21st step reading in the 0.08d region.

Typically, we never subtracted B+F in our densitometry tests for motion picture work, but the aim points and application for these tests bore little relation to testing for Zone System manipulation. I am biased to keep the B+F in the calculation, but that is most likely just stubborn familiarity...

I don't want to start a running battle over subtract/don't subtract B+F, as in the past I have witnessed page after page of arguments here on Photrio for and against the practice which did not seem to change any participant's mind on the subject matter. As Mr. Bill says, "whatever works for your purposes."

Thanks for the input; I will have to give this a bit more thought as how to proceed.



Correct. I should have said "step 21" not Zone X! (and even that is not quite right).

Click to expand...

Andrew O'Neill said:

...and recently, I've even used my UV LED light box to expose slow films. Field tests confirmed that it's fine to use. Quicker exposure times, not having to worry about reciprocity effects.

Click to expand...

Great idea! Would facilitate paper negative testing as well!

Kino said:

Great idea! Would facilitate paper negative testing as well!

Click to expand...

It would, indeed. I've exposed Lodima papers in it!

Zero the densitometer to the film base.

In 40 years of doing densitometry I have only infrequently measured the film base.

ic-racer said:

Zero the densitometer to the film base.

In 40 years of doing densitometry I have only infrequently measured the film base.

Click to expand...

Exactly.

Film base is important
-it might be tinted as much as 0.25 for 35mm film but 0.05 is what I think of as typical for 120 and 4x5
Fog is important
-if under 0.05 that’s pretty good
-this is what affects film speed, especially when comparing developers of working with expired film
When evaluating speed you subtract film base and fog
Graphs of curve families that include film base plus fog tell a story of fog rising with development time
But when you want to evaluate speed you’re going to want to knock it off