Sensitometry for stained negatives

Interesting results and not surprising. Thanks for posting this.

Stephen Benskin said:

A long time ago, I teamed up with Kirk Keys over a similar question. He felt there was some special properties in staining and I believe it had more to do with the development velocity. We ran a bunch of film, but didn't get much past that stage. Below are the results for FP4P developed to a CI 0.56 in Xtol and PMK. Part of the print testing was going to determine which read densities best represented the results. If I remember correctly, I felt the Visual setting is most likely represent how the film would respond in an enlarger's light.

View attachment 413023 View attachment 413027

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Milpool said:

Interesting results and not surprising. Thanks for posting this.

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It's very useful to know that measuring blue is not really that useful for regular enlarging. Measuring through the filter is a PITA and I might not bother in future.

This caused me to notice something interesting in the Unblinking Eye staining developer article. One of the only films there that is analysed with the same dilution and dev time in both blue and UV is HP5+ at 2+2+100
fig12 is UV


fig20 is BLUEThis does raise the question of why UV and BLUE were chosen (vs UV and vis, which would have been different, there's a few bits in the article that are a bit of an irritant in trying to compare the various charts).
This would seem to imply that measuring a blue channel might be useful for checking density range for alt processes maybe? No substitute for a UV densitometer, but I've not long brought my printalyzer, and can't really justify upgrading to the UV version.

I have been proceeding under the assumption that agitation is going to indirectly affect EI for the reasons I specified above - more agitation = faster highlight development = less time for shadows to develop = lower effective EI at a given contrast index.

But now I am curious enough to challenge that assumption. Maybe I'll cut a roll of HP5+ in half and develop one half with my normal Ilford agitation and the other half rotary to see if the densities come out differently. Rule of thumb is to cut development time by 15% for rotary processing, right?

Is sheet HP5+ emulsion different from roll HP5+ in a way that would change development between the two?

Milpool said:

For reference here is the original specified formula. It's different than D-76/ID-11. Apparently one of the reasons for the standard change to remove the specified developer was that Kodak had trouble getting the earlier T-Max films to quite reach box speed with it (recall there was a time when the T-Max films were labelled EI rather than ISO).

(/l)
0.5g metol
40.0g sodium sulfite (anh.)
1.0g HQ
1.5g sodium carbonate (anh.)
1.0g sodium bicarbonate
0.2g KBr

pH 9.4 +/-0.2 @ 20C

At that time the standard also specified the fixer formula.

Regarding gamma in the standard keep in mind this is required between the speed point (Hm) and a point Hn 1.3 logH (4 1/3 stops) higher. In Zone System parlance that would be the range from Zone I 2/3 to Zone VI.

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Just to clarify for everyone else, and I hope this isn't overly pedantic, but there is no gamma in the standard or at least not the gamma term referring to the measurement of the straight-line portion of the curve. Nor does it use CI or G-bar. Technically you could use the generic version of gamma (simply rise/run for any given portion). It just doesn't have a corresponding gradient method. It's more of a contrast parameter. The film curve needs to fit the parameters. The Δ1.30 log-H and Δ0.80 density range (ΔD) equals a gradient of 0.615. A short-toed film will have an approximate average gradient of 0.61 under these conditions. A long-toed film will have a higher average gradient of 0.65 or slightly higher. The reason for this is to fit the mathematical conditions to fit the Delta-X equation.

BHuij said:

I have been proceeding under the assumption that agitation is going to indirectly affect EI for the reasons I specified above - more agitation = faster highlight development = less time for shadows to develop = lower effective EI at a given contrast index.

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One factor with Pyrocat is also oxidation. I usually use 1+1+100 and ilford agitation, but I noticed that when doing 4x5 in an SP445, the developer is notably less brown after the finished dev time. I've put this down to the sp445 just being a bit fuller, and me having a less aggressive inversions (because the thing leaks badly enough without extra encouragement). This caused me to be a bit more gentle with my inversions when doing roll film in a patterson.
I've not tested to see if this is keeping the developer a bit more active for longer. I need to do a proper test at some point.

Agreed. I should have been more careful in the wording. It's just the basic slope between two points. Interestingly (or maybe not) that's often how Zone System calibration is done.

I dug up an ancient diagram I made (two hypothetical films having the same ISO speed). The red curve is of the longer toe/"upswept" variety. One of the few remaining general purpose films (maybe the last) with this characteristic by design is TXP 320.

Stephen Benskin said:

Just to clarify for everyone else, and I hope this isn't overly pedantic, but there is no gamma in the standard or at least not the gamma term referring to the measurement of the straight-line portion of the curve. Nor does it use CI or G-bar. Technically you could use the generic version of gamma (simply rise/run for any given portion). It just doesn't have a corresponding gradient method. It's more of a contrast parameter. The film curve needs to fit the parameters. The Δ1.30 log-H and Δ0.80 density range (ΔD) equals a gradient of 0.615. A short-toed film will have an approximate average gradient of 0.61 under these conditions. A long-toed film will have a higher average gradient of 0.65 or slightly higher. The reason for this is to fit the mathematical conditions to fit the Delta-X equation.

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The sensitometry of HP5+ itself should be format-independent.

For a given target average gradient / slope, agitation can have an effect on a Zone System EI, however assuming the EI is determined solely using the fixed density criterion (Zone I) this effect will generally be very small. There will be some variability depending on the film and developer but in the end the differences in EI due to agitation/dilution will be mostly noise once you pick a developer. You have to get fairly extreme to have an effect. For example the difference in EI between say XTOL stock/constant agitation and XTOL 1+3/extended agitation intervals made virtually no difference when I ran that. You might get slightly more of a difference with an extremely dilute, high pH/weakly buffered developer.

I once did an experiment with the in(famous) Rodinal 1+100 / stand development method to compare EIs / curve shapes. The results were that it made little difference. Of course you can imagine that was not a popular post...

BHuij said:

I have been proceeding under the assumption that agitation is going to indirectly affect EI for the reasons I specified above - more agitation = faster highlight development = less time for shadows to develop = lower effective EI at a given contrast index.

But now I am curious enough to challenge that assumption. Maybe I'll cut a roll of HP5+ in half and develop one half with my normal Ilford agitation and the other half rotary to see if the densities come out differently. Rule of thumb is to cut development time by 15% for rotary processing, right?

Is sheet HP5+ emulsion different from roll HP5+ in a way that would change development between the two?

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Here is a CI / Time curve for TMX 4X5 in both Xtol and PMK.





While Kirk and I didn't complete the testing, my initial reaction was that the Low - Low of PMK could account for much of the perceived contrast control of the staining. It's really hard to over process and precision processing isn't really required in this example. Here are the results for Normal processing for the tested films. The test was to check if the higher blue level would interact with the yellow filter of a multigrade paper creating lower contrast in the denser areas of the negative.


And a curve comparison between FP4P in Xtol and PMK. The PMK curve is adjusted so that the two curves match up at 0.10.

The only time I have used pyro it gave really flat negatives. I don't remember what version it was, the one Sandy King developed. I followed the recommended times and in order to get anything resembling a normal looking print I was using grade 4.5. I've stuck with conventional developers ever since.

I spent years testing over 100 film and developer combinations under the BTZS system with Phil Davis. There are a few findings that apply to this discussion:

1) Variability in film speed was commonly 1/3rd of a stop or more due to other variables including film age, freshness (sometimes too fresh) of developer, process temperatures and temperature variations.

2) Exposure time especially with in-camera methods were fraught with shutter and aperture errors when compared to lab-based exposures.

3) Agitation (BTZS Film Tubes and Jobo Systems) had little effect except to make the system more repeatable. Oxidation was an issue with some high concentration developers like PMK and ABC Pyro which affected development times and sometimes mid-curve shapes affecting EI calculations.

4) While film speed is certainly important to determine, paying attention to the overall curve shape (Super XX versus Tri X for an example) is more important when trying to understand the placement of values on that curve.

5) With many developers, films like TMX and TMY often exhibited "box" film speeds.

6) Other films like TX were regularly found to be half box speed even with custom developers designed to increase EFS.

7) Equipment used to make the exposure was responsible for drifts of almost 2 stops (bad reading practices and shutter issues) far outweighed 1/3+ stop differences in film speed.

Finally, cross-calibration of your step wedge with multiple (nicer) densitometers is critical. We often found retail (instead of calibrated) step wedges to be non-linear to up to 0.03 density units not only step-to-step but also within a range in the middle of the scale.

I taught the BTZS system for years and learned that equipment repeatability had far more to do with good exposures than developer/film combinations. Check that shutter (repeatable) timing in cold and hot weather, be sure you are using your meter consistently and it will all be ok.