Progress on XTOL-concentrate

[albada]

At this point, I think we can conclude that D316 will not fail with low-speed films, as DS-10 did. I've tested the following slow films:

Ilford Pan-F+, Ilford FP4+, Fuji Acros

All did fine in D316.

Yesterday, I ran some rolls of Delta-400 in both XTOL (7.5m) and D316 (15.75m), and compared them on the light-table. Measurements and loupes show results similar to Tmax-400: Compared with XTOL, D316 gives about the same film-speed, slightly finer grain and a little less sharpening. Here are the graphs of Delta-400 in both soups:



As we've seen before, D316 also creates a higher shoulder, which I suspect is due to D316's stronger buffering. That will give better gradation in things like clouds, snow and white clothing. But this improvement is substantially better than what I've seen in other films. Any idea why? Using Ilford's recommended time of 7.5m, Delta-400 in XTOL gave a Contrast Index (CI) of only 0.50. But 0.58 is needed to print at grade 2, so this is a little low (grade 3?). In the graph, D318's CI is 0.52. I matched XTOL's CI so that I could compare grain, but I suggest using a little longer time to boost contrast.

Here are the times I have so far:

Tmax-400 ......... 12
Tri-X .................. 13
Acros ................ 13
Neopan-400 ..... 13.75
Pan-F+ ............. 12.25
FP4+ ................ 16
Delta-400 ......... 16.25

Today I'll be souping some Tmax-100.

Mark Overton

[Bruce Osgood]

Today I'll be souping some Tmax-100.

Mark Overton

I'd like to know your results with Delta 100.

[albada]

A surprising result: With Tmax-100 (TMX), D316 acts like a compensating developer. Here's the graph of D316 and XTOL:



Compared with XTOL, D316 has (1) a slightly higher toe (giving a bit higher film-speed), (2) same midtones, and (3) compressed highlights. With most films, D316 gives the same or higher shoulder; with TMX, the shoulder is lower and sooner. While helpful for high contrast scenes, this is supposed to be a general purpose developer. The leader density is also lower (2.11 vs 2.28).

Any idea why this happened? I believe that compensation occurs due to either a drop in pH (poor buffering) or developer starvation. D316's buffer/phenidone ratio is better than XTOL. Its AA/phenidone and sulfite/phenidone ratios are similar, so why would the phenidone be starving?

Is this simply a case of underdevelopment?
Would multiplying the amount of both sulfite and concentrate by 1.5x or 2x help?
Or perhaps boost the sulfite in order to boost pH closer to 8.2?

Mark Overton

@Bruce: When I'm done with Tmax-100, I'll test Delta-100.

[Photo Engineer]

Mark;

I would suspect underdevelopment until proven otherwise.

PE

[albada]

Mark; I would suspect underdevelopment until proven otherwise. PE

I dev'd a roll today in D316 for 15.5 minutes (the prior was 14). The leader-densities are:

XTOL: 2.28
D316 14m: 2.11
D316 15.5m: 2.41

Here are the curves for both of those and XTOL:



Do you think it's possible to match XTOL's curve? If not, imagine a curve halfway between those two corresponding to about 14.75 minutes. It's not what XTOL would produce, but would be similar to Tri-X. Maybe that would be acceptable?

Mark Overton

[Photo Engineer]

I doubt if you can match XTOL, but the results look interesting.

Thanks.

PE

[Gerald C Koch]

Mark,

In order for the graphs to be really meaningful and to draw conclusions there nust be at least three seperate measurements for each data point. This means 3 trials for each developer noted on a graph. Then the various points can be shown with error bars. It is only after this that one can be confident of the relative placement among the curves. It is possible that the curves for Xtol and your developer to fall within each others confidence limits.

The following site may be helpful http://www.pafaculty.net/biology/kei...Deviation.html. It's a lot of work but necessary.

Jerry

[albada]

I doubt if you can match XTOL, but the results look interesting. Thanks. PE

A surprise: D316 (at the shorter dev-time) is delivering finer grain than XTOL in the shadow- and midtone-portions of the curve where it matches XTOL's curve. In fact, even the overdeveloped D316 roll matches XTOL's grain (judged by 22x loupes). The curve's shape looks like Tri-X. Here are the two TMX/D316 curves with the Tri-X/XTOL curve (in red) for comparison:



I think I'll boost dev-time of the green curve a little (to 14.5 min) to match the curve of Tri-X, and say, "If it's good enough for Kodak, it's good enough for me." And grain should still be finer.

PE: I appreciate all the help you provide. Thanks!

Mark

[albada]

Mark,

In order for the graphs to be really meaningful and to draw conclusions there nust be at least three seperate measurements for each data point. This means 3 trials for each developer noted on a graph. Then the various points can be shown with error bars. It is only after this that one can be confident of the relative placement among the curves. It is possible that the curves for Xtol and your developer to fall within each others confidence limits.

The following site may be helpful http://www.pafaculty.net/biology/kei...Deviation.html. It's a lot of work but necessary.

Jerry

That's the advantage a corporation has: They can have engineers and testers work full-time on a project. Those of us doing this as a hobby in evenings/weekends take short-cuts. My short-cut has been to develop just once, and if all looks normal, accept that and proceed to the next test. Also, I have tight control over temperature, exposure, agitation, etc. to try to improve the chance that my first try will not have any anomalies. But your point is that there is still test-to-test variation, and only multiple tests will reveal the variation-ranges.

Do you have any ideas of how to get variation-ranges (error-bands) without tripling the amount of effort? Maybe if I make three runs of the most popular films, and just one of the others? Or three runs of anything that looks odd? Or maybe others could volunteer to share the tedious testing effort?

Mark

[Gerald C Koch]

The problem with doing only obly one run for each film is that you can't determine what error limits there are. Statistically they can be very high. In an analysis there are two factors; accuracy and reproducibility. You can have a set of values that have a very high degree of reproducibility but are yet far from the real value. Conversely you can have a set of values with little evidence of reproducibility whose average is very close to the real value. Without doing a statistical analysis any data is suspect. Your analysis is better when you include Xtol since it can be said to be a standard and validates your method. At a very bare minimum you need two sets of data. A spreadsheet can take away the drudgery of the mathematics. I personally would stick to tier one films since their quality control removes another variable.

Jerry