Progress on XTOL-concentrate

[albada]

When you are making huge batches and you are running continuously, and if you are rich enough to scrap a marginal batch, well then, things are nearly perfect. It appears as if things are not near perfect.
Of course, this assumes that Marks process and data are spot on.
PE

I re-checked my records. I developed a roll of Neopan 400 two days before the TMY2 rolls, and one day after. Both Neopan rolls came out fine. Here's the graph of the day-after Neopan roll:



I've improved my methods to eliminate some wobbles in earlier graphs. Here's a graph of batch 0166 of TMY2:



This one has wobbles, but you can see that it's roughly a straight line, unlike the latest TMY2 (batch 0167).
What do you think of these graphs I've been posting lately? Do they look like what you'd expect?

Mark Overton

 

[Photo Engineer]

Yes, they look OK to me.

The sag in the middle of 0167 is a tipoff to me that there is a mismatch in speeds of the 2 emulsions. Of course, 166 and 167 may be cuts from the same or adjacent master rolls in the same batch and what we are seeing is the difference in handling due to outside factors, and the film may have passed the release test.

PE

 

[Kirk Keyes]

Any idea why this occurs? Is this a well known phenomenon?

Mark Overton

You're testing with 35mm film, right? It would be interesting to compare with 4x5 sheet film.

 

[Kirk Keyes]

Converting 1.73 into stops: 1.73/0.3 = 5.75, which means that CI (at .58) assumes the scene contains 5.75 stops of luminance-range. Isn't that too low? I thought scenes contained a larger range than that, around 7 stops. It appears that CI is ignoring some of the highlights. Or did I miss something?

Mark Overton

Paging Dr. Benskin. Paging Dr. Benskin.

OK, he must be off today...

Think about lens flare and its effect on the luminance range. 7 stops in the real world will drop somewhat as the light goes through your lens on its way to the film.

 

[Kirk Keyes]

Shifting curves (on 2 sheets of paper and over an illuminator)

PE

PE, do you still have your French curve, or did you like to freehand it? I miss French curves, and actually stencil templates in general.

 

[Kirk Keyes]

When you are making huge batches and you are running continuously[…]
PE

PE, When pouring out 5000 ft of film, how much deviation was there from head to tail, and what was acceptable? Was EK able to get it pretty much the same for the whole roll?

 

[albada]

Paging Dr. Benskin. Paging Dr. Benskin.
OK, he must be off today...
Think about lens flare and its effect on the luminance range. 7 stops in the real world will drop somewhat as the light goes through your lens on its way to the film.

Kirk, thanks for chiming in. Yes, I test with 35mm film. The Stouffer chart I got is intended for 4x5, forcing me to do some adapting. Do you think using sheet film would give different results?

Hmmm, flare will push up the shadow-area, compressing the entire image a little, so I can see why 7 stops would become 6. So Kodak's 5.77 stops in its CI-ruler is close after all. Thanks for pointing that out.

Mark

 

[albada]

Knowing their cause allowed me to filter out the wobbles in the 0166 graph. Here's a comparison between Tmax-400 (TMY2) batches 0166 and 0167 developed identically in D316 (plus XTOL for comparison):



What's interesting is that the slope of the upper half of 0167 is correct.

Mark Overton

 

[Rafal Lukawiecki]

Hmmm, flare will push up the shadow-area, compressing the entire image a little, so I can see why 7 stops would become 6. So Kodak's 5.77 stops in its CI-ruler is close after all. Thanks for pointing that out.

I remember Stephen pointing out that a typical scene has 7⅓ stops, and a fixed flare model used by Kodak assumes a compression worth 1⅓ of a stop. I found this (there was a url link here which no longer exists) posted by Stephen, informative. It shows the CIs, after factoring the fixed flare, for various SBRs, and aim LERs. Nonetheless, I think Stephen prefers a variable flare model, where the amount of flare is proportional to the scene luminance range.

 

[Photo Engineer]

Mark;

That comparison suggests that the two films react differently to different developers. I'm surprised at the contrast To be sure, there should be 4 comparisons. You should have another Xtol cmparison, 166.

PE

 

[albada]

Good news: A second roll of TMY2 batch 0167 worked great! I changed two things:

* All non-developer liquids (presoak, stop, fix, wash) were at the higher temperature of 22-24C (instead of 18-19C).
* I mixed fresh TF-4 fixer.

Unlike the last try, the following occurred as expected:

* Fixer poured out magenta (instead of clear).
* Wash-water poured out magenta.
* Film had no residual magenta colouration.
* Density-curve is perfect, as shown below:



The first symptom that changed is the colouration of the fixer, so perhaps old TF-4 fixer fixes not only the image but also the magenta dye? The old fixer was clear (not yellow) and had a clearing-time of 60 seconds, so I thought it was fine. But it had 51 rolls run thru it, and the instructions said it is good for 28. Oops. Could old fixer partly bleach the silver image? It's hard to imagine why densities would be low.

Mark Overton

 

[Photo Engineer]

'ello mate. You are using British or Canadian spelling of COLOR Mark.

So, there is an unknown variable in these tests that cause a problem! Before you go on, you must identify that variable. Find out if it affects all films or just this one batch etc....

PE

 

[Kirk Keyes]

I changed two things:

* All non-developer liquids (presoak, stop, fix, wash) were at the higher temperature of 22-24C (instead of 18-19C).
* I mixed fresh TF-4 fixer.

I would keep everything at the same temp. Look into getting a Jobo processor or Jobo tempering bath. They make it really easy to getting temps all the same.

I'd suggest using a two-bath fixing scheme. The oldest fixer bath gets used first and then the freshest fixer bath second. That way you do all the heavy fixing with the first bath, and then the second bath can clean up the last bits of unfixed silver.

I think a two bath fixer scheme would even out variations in fixer life-cycle.

 

[albada]

'ello mate. You are using British or Canadian spelling of COLOR Mark.
So, there is an unknown variable in these tests that cause a problem! Before you go on, you must identify that variable. Find out if it affects all films or just this one batch etc.... PE

First, Kirk: Thanks for the suggestion about a two-bath method of fixing. For me, fixer costs almost nothing compared to rolls of film, so I'll probably simply replace my fixer much more often.

@PE: Does my personality have color or colour? The apug spell-checker red-marks American spellings as wrong, and since British English is the international standard, I figured I should spell things that way.

There's another variable I neglected to mention: The plastic lid for the SS tanks had a orange-brownish residue on them which I noticed after the bad TMY rolls, and which I cleaned off. My beaker dedicated solely to fixer also has a slight orange colour-cast, so the TF-4 fixer leaves a bit of insoluble residue. But the amount is so small, and the prewash removed some magenta dye (unlike later steps) that I doubt this residue was the cause of failures. Note that I wash film with the lid on, so this residue survived all that washing.

I discarded the old fixer, so I can't reverse that change.

Today, I tried a roll of TMY2 with cool liquids for everything but developer. It made no difference (everything worked fine).

Listing the changes:
* Insoluble residue - exceedingly unlikely to affect anything.
* Temperature - had no effect.
* Old TF-4 fixer - that must be the cause!

I suspect that well-used TF-4 accumulates a chemical that prevents dissolution of the magenta dye. In addition, it seems to do some bleaching. "Well-used" meant 51 rolls in 1.5 litres, including about 20 test-strips which would dilute it a little.

Your opinions about this? I wish I'd kept the old fixer.

Mark Overton

 

[Photo Engineer]

Mark;

At this time, I have no clue. Sorry.

PE

 

[albada]

D316 works fine with all films made by Ilford, Kodak and Fuji.
I've crunched all the data and am finishing some retesting. The only real surprise is that Delta 3200 takes 25 minutes to develop. I'll post all the dev-times in not too long.

Fuji Acros has an interesting density-curve. Here are curves from two rolls with different dev-times:



When most films start shouldering off in extreme highlights, Acros shifts into overdrive and ramps back up after X=0.3. As a result, the curve has a small swale from X=-0.3 to X=0.6. The upward slope of the swale won't affect photos unless they're badly overexposed, but I thought I'd point out this odd behaviour. BTW, these two curves are shifted horizontally a little because I've been tweaking my methods.

Mark Overton

 

[Photo Engineer]

Looks like Fuji is having trouble blending emulsions too. That is the usual result from a minor mismatch in either speed or contrast.

PE

 

[albada]

Your Acros curves are consistent with the repeated testing I've done with that film in a variety of developers. Finally someone has confirmed my results!!!
[...]
Michael

You did your tests "a few years back", so surely Fuji would have discovered this by now. Perhaps it has a small enough effect on most people that they haven't bothered to fix it.

Looks like Fuji is having trouble blending emulsions too. That is the usual result from a minor mismatch in either speed or contrast. PE

Interesting. In my ignorance of film-design, I'll speculate that Fuji's low speed emulsion in Acros needs to be a little faster and less contrasty. Am I close?
Kodak's TMY2 is more worrisome. Here are curves from batches 0166 and 0167:



All were developed in D316 for 12 minutes. The green line is batch 0166 -- it's so straight that it's almost ideal. The red line is batch 0167 with old fixer, which has an obvious break. What bothers me is the black line, which is batch 0167 with new fixer: It is sagging with its inflection at the same point as the red line. That tells me the emulsion issue is still there.

That would mean there are *two* problems:

• Poor blending of emulsions.
• Old fixer that messed up the magenta dye and made the neg thin for some reason. It occurred to me that each time I fix, the fixer pours out magenta, and I'm therefore putting magenta chemicals into the fixer for each roll. So I'm not surprised that after a while, chemical-buildup in the fixer affected the film.

BTW, my tests of batch 0167 shows that a pre-wash increases density, as was true of batch 0166. I have no clue why.

Mark Overton

 

[albada]

I was referring more to the increase in contrast in the highlights. I did not observe any significant "sag" before the highlights took off. I observed a pretty much straight line until there was a sudden increase in slope - which then remained straight until the rather abrupt shoulder.

That's just what I'm getting now with TMY2 batch 0167, although I haven't hit it hard enough to see what the shoulder looks like. It sounds like Fuji's curve has changed some over the past few years with the introduction of a sag before the big rise.

I see little benefit and a substantial cost to having a higher slope in the highlights. If one prints so that shadows and midtones have normal contrast, then the highlights block up more. What good is that?

Mark Overton

 

[Photo Engineer]

If both batches of Kodak film look the same in D76 at the recommended times/temps, then there is an interesting question here. Can you try that test? you see, there are some classes of developer that just cannot develop some films correctly.

As for the Fuji film, either there is not enough fast component or the slow component is too fast or both.

PE

 

[albada]

If both batches of Kodak film look the same in D76 at the recommended times/temps, then there is an interesting question here. Can you try that test? you see, there are some classes of developer that just cannot develop some films correctly.
As for the Fuji film, either there is not enough fast component or the slow component is too fast or both. PE

Yes, I just verified that I have both Metol and HQ here, and I have one roll of TMY2 left, so I can dev it in D76.

A question about toes:
Notice the toe between densities of .1 and .2 in the graphs below:



In both, D316 has a slightly softer toe than XTOL. The difference is small, but I see it often enough to know it's really there.
How can I boost the toe?

Would reducing buffering by reducing ascorbic acid (AA) and metaborate help? Reducing AA would also restore phenidone less in dense areas (or so my theory goes). Maybe adding KBr or BZT?

Thanks,

Mark

 

[Photo Engineer]

Mark, it is pretty tough to evaluate the data in those curves the way the data is presented. I'm not sure that there is a significant difference though.

PE

 

[albada]

I ran a roll of TMY2 batch 0167 through D-76. The curves (using two lenses):



There's a small inflection at X=-1.4. That also is the location of the transition between the lower and upper rows of the Stouffer step-wedge, suggesting the problem is uneven illumination. But curves for other films look fine, with no inflection there, so maybe that's just a coincidence. It's hard for me to say, and I'm going to change illumination to hopefully insure uniformity by adding more diffusion.

On a different topic, I plan to reduce both metaborate and ascorbic acid in D316 to see what effect that has on the toe. Some similar experiments I did a few months ago look encouraging.

Mark Overton

EDIT:
Michael R: If you re-measure Acros, could you post the curve? Or maybe post the numbers and I can plot them using gnuplot and will post that. Thanks!

 

[Photo Engineer]

Mark;

This seems to be a case of the two films being within an hair of each other in D76, but wildly different in your developer. I've seen that and have mentioned my 13 developer experiment where several coatings gave me different results in 12 of the developers but were identical in the release developer.

This means that your work is not done. If different releases of the same product look alike in a standard developer, but look very different in your developer there may be something wrong with your developer. One way to confirm this is to use another accepted developer such as HC110 to see what happens. If these two films are the same, then the fault lies within the developer and not the coating in the sense of this severe variability.

That does not mean that these coatings are good IMHO. The curves still sag too much in the middle.

PE

 

[albada]

Mark;
This seems to be a case of the two films being within an hair of each other in D76, but wildly different in your developer. I've seen that and have mentioned my 13 developer experiment where several coatings gave me different results in 12 of the developers but were identical in the release developer.
This means that your work is not done. If different releases of the same product look alike in a standard developer, but look very different in your developer there may be something wrong with your developer. One way to confirm this is to use another accepted developer such as HC110 to see what happens. If these two films are the same, then the fault lies within the developer and not the coating in the sense of this severe variability.
That does not mean that these coatings are good IMHO. The curves still sag too much in the middle. PE

I know I've had problems with non-uniform illumination. Here's an example:



That big inflection is my fault. I'm learning that it's difficult to photograph a back-lit step-wedge through a lens. A uniform light-source usually isn't uniform enough, and lenses introduce variation in brightness from centre (spelled correctly ) to corner, especially wide open. Here are results after supposedly fixing the problem:



My developer (D316) and XTOL are close, and not wildly different, so I think D316 is fine. The curves are much better, but that inflection is still there in both. Rather than blame Kodak, I'm going to assume this is entirely my fault and (1) add more diffusion to the light-source and (2) use a longer lens. I like Michael R's method of simply taking a bunch of shots at various f-stops of a known light-source.

@Michael R: Flare is another problem that your method avoids. I've recently started taking two shots of the step-wedge, the 2nd with the upper row of wedges blocked to eliminate their blast of light that adds flare to the bottom row. You are correct: That flare pushes up the toe-area. The only reason I'm still trying to get step-wedges to work is so that when experimenting with developer formulas, I can develop two-frame-long strips instead of a roll at a time. I'm interested in seeing your results, and TIA for doing those measurements.

Mark