Speed loss for Delta and Tmax

I need to shoot some "must come out right" images and need to choose a film to use. Many years ago I had an issue with speed for Delta and Tmax film which I have never been able to answer properly, and this still worries me, and hence biases my choice. I am hoping perhaps to get a better understanding of what happened and how I can avoid the issue.

First let me present the issue (this was perhaps 15 years ago). I was shooting a lot of Delta 3200 developing in Rodinal. I was getting very consistent results for years then suddenly I had an apparent drop in film speed. To cut a long story short, I found I had a speed loss for Delta 3200, Delta 100, Delta 400, Tmax 100 and Tmax 400. Convetional films FP4+, HP5+, Tri-X, APX-100, and APX-400 all gave good results. I should point out that at this time I had access to a high grade densitometer, and before the issue I could CONSISTENTLY shoot a test roll, develop and get density reading to within the accuracy of the densitometer. I tried different chemicals, even going to the extent of using a different developer, different fixer, different source for distilled water, and even developing using a different tank, and different measuring equipment etc. I tried shooting in different cameras. I even tried 120 and 135 films. In one test I shot a roll of tabular grain film and conventional film and developed them together with the tabular film showing a speed loss, and the conventional film being spot on. Note the effect was a speed loss, the contrast was good. At the time I researched as much as I could but I was not able to get a possible explaination for the issue.

Since then at some time the tabular grain films "came good", but I still always have a concern in the back of my mind with the tabular grain films.

So has anyone seen something like this and found the cause??

Thank you in advance.

What was the light source for your sensitometer or how did you do your test shots? I use an EG&G sensitometer which uses electronic flash for a light source.

How much difference in speed did you find?

I have been puzzled by a relative speed difference I find between tabular grain and conventional grain film. The difference is 2/3 stop. For me, vintage Panatomic-X tests relatively "faster" than all other film.

I came to the conclusion that the issue may be spectral absorbtion characteristics of my No.96 filter, a dye based gelatin Neutral Density filter, which I must use in tests for faster film. But I also consider the possibility that the films themselves have different spectral sensitivity which causes test results to vary (without necessarily proving the film speeds are really different). So the light source you use for tests may be important to what you found.

When you say a speed loss do you mean that up to a certain point you were getting full speed/box speed then suddenly you found that the speed had dropped or do you mean that you previously has assumed a certain speed which when you checked wasn't the speed you had assumed it was.

If it was the former then something clearly changed except, if I may be so bold, the actual manufacturer's measured speed of the film which is what you seem to feel it might be.

What the change or changes was/were I have no idea and those with ideas can only list them for your consideration but as it was 15 years ago can you be sure of the kind of changes that might have occurred other than your suspected inherent film speed change.

In practical terms I'd re-do the tests to see what transpires but given the range of films you mention I am not sure Rodinal would be my first choice of developer.

Ilford DDX or possibly Microphen might be better Ilford choices for the test or Kodak's Xtol or TMax

pentaxuser

The test shots were daylight exposures of 1/3 frame = white card, 1/3 frame = grey card, 1/3 frame = black card. My typical setup when trying to dial in a film. Exposures were cross checked between a silicon photocell meter, a CdS meter, and a Selenium cell meter. All agreed which is the typical case for daylight.

The speed difference I observed was significant. About 1.5 to 2 stops. It was consistent (i.e. I could repeat the test shots and get the same densities).

It was a genuine speed drop. I developed a batch of films and found all my shadow detail was gone. That started my investigations. Luckily those shots were not critical, but ever since then I have been cautious about using tabular grain film for critical images.

Rodinal was a wonderful developer for Delta 3200. I much preferred it to DD-X. It gave really crisp grain which improved perceived sharpness compared to DD-X. Of course each to their own.

Thanks Urmonas,

That's interesting, I've never lost more than one stop, unless I underdeveloped significantly.

Even last Friday, I lost only a third-stop when a sheet I was developing only got 0.38 Contrast Index.

You said the contrast was good. What kinds of notes did you keep on the tests?

With the three patches you might have enough information to evaluate the gradient. Did you keep those kinds of notes? It would be obvious like the density corresponding to the white patch falling at or below 0.80 - that would corroborate a one-stop speed loss due to low development activity.

Otherwise the next line of questions... What developers did you use? Hoping some of your experiments had Metol, like D-76.

Other question is, are the films "fresh" and their storage condition ?

Urmonas said:

Since then at some time the tabular grain films "came good", but I still always have a concern in the back of my mind with the tabular grain films.

Thank you in advance.

Click to expand...

I think you mean that at some point in the more recent past i.e. less than 15 years ago when you did your tests, tabular films achieved box speed.

I don't think you mean you tested tabular grain films again to verify otherwise you wouldn't have needed to post but if your belief that tabular films have come good in the recent past isn't based on your tests then can I ask what is your belief based on and when do you think this "coming good " happened?

Thanks

pentaxuser

Multiple films, multiple manufacturers, so that's not it.
Multiple formats, so not a camera problem.
Developed yourself and verified visually and by metrology. Not a lab problem.
Problem disappeared.
1 developer, how many bottles?
Distilled or tap water?
How many light meters?
How many thermometers?
How many timers?

Hopefully I will cover all the questions:

I did not measure the white or black card sections of the images at the time. I still have the films, but at the moment they are in storage, so I can't get to them quickly. I also do not have access to a good densitometer at the moment, so could only do rougher measurements. I did do a full sequence of exposures (1 stop increments) so I know gamma / G-bar / CI were as expected i.e. matched the results I had before the issue arose, just everything was shifted down in speed.

The two developers I used were Rodinal (my standard at the time) and as an alternative ID11. I did not use ID11 regularly at the time so used published development times for my cross checks.

The films were fresh. All purchased from reputable local stores which had good turn-over of film (which 15 years ago was still heavily used).

Correct about the "came good" comment. I have used tabular grain films more recently and have acheived my previously tuned in speeds.

FInally: Actually 2 developers, Rodinal was my main developer at the time, and to cross check I tried ID11

Developers and fixer mixed with de-ionized water (and I tried distilled water from a different source as well). Rinses with water from a drinking water filter (one of those gravity feed home use filters) I tired changing the filter cartridge just in case. The final rinse which was with de-ionized / distilled. I did try one run with all distilled water (including rinses) with no change in results.

3 handheld light meters used, one silicon cell, one CdS and one selenium. I also had in camera metering for the 35mm. All meters agreed to with less than 1/3 stop.

As a cross check I tried all different equipment (in case something was "contaminated"). So different tank, different reels, different graduated cyclinders, different thermometer, even different film clips for drying. The only common thing would have been the timer, but that was been reliable.

Note that I had no trouble with conventional films (and I tried a range of them). I even developed a tabular film and conventional film in the same tank (I chose a pair which required similar development time). Conventional film was behaving as expected, tabular grain film showed slow speed.

Urmonas said:

Correct about the "came good" comment. I have used tabular grain films more recently and have acheived my previously tuned in speeds.

Click to expand...

Thanks. As I said, short of replicating your tests exactly to see if there is a cause that isn't the one you believe to be the case, namely manufacturers' ( Kodak and Ilford) recent increase in the speed of tabular grain films, then I feel there will be no way to get to the bottom of it.

However on a practical note, if both manufacturers have increased speed so tabular films now achieve the same speed as their conventional ones then your concern about tabular films has gone, hasn't it?

The only way you might still be at risk is if both manufacturers' processes increased the speed without anyone in charge realising i.e. the process is acting in some kind of random fashion and we are now in the "box speed" phase but this may not last.

For this to be the case it would suggest that both manufacturers' processes for tabular film making are in the strict sense "out of control" and none of the controls and tests done on a regular basis by both manufacturers can keep the process in control.


I can't speak about Kodak but having see around Ilford twice along with many other APUGers I'd be surprised if anything is out of control unbeknown to Ilford.

However at the end of the day you must believe what you must believe and act accordingly but I think that there is little risk that you cannot continue to rely on the issue, if it stems from the manufacturers' processes, staying fixed.

pentaxuser

Urmonas said:

In one test I shot a roll of tabular grain film and conventional film and developed them together with the tabular film showing a speed loss, .

Click to expand...

"Shot a roll" is consistent with an exposure index test. Not a film speed test.
When you developed the films together they were confirmed to have the same contrast index; they both fit the ASA triangle?
How are you measuring speed?
Your exposure index will be influenced by your shutter accuracy, metering accuracy, aperture accuracy, meter calibration, light wavelength, etc. As long as you are processing to the appropriate contrast for the ASA triangle, the developing conditions would have only a small effect on your exposure index.

Pentaxuser - This is not a manufacturing effect. I cannot image even the worst fim manufacturer having a 1.5 to 2 stop change in film speed. The issue is that I had Delta 3200 "dialled in" then suddenly it was exhibiting a large apparent speed loss. A range of tabular grain films showed a similar apparent speed loss, but conventional films still behaved as per my "dialled in" measurements. My concern is that without knowing the cause I don't know how to avoid a similar effect again. The question comes down to what could affect tabular grain film speed but not affect conventional grain?

ic-racer - I based my film speed on 0.1 density over FB+F. Development time is based on contrast (ASA triangle). I agree that development conditions should have little effect on EI, but for some reason I had tabular grain films suddenly lose speed, almost as if I had a ND filter in place. The exposure curve was close to what I expected, but shifted down in speed.
Conventional films shot in the same camera and developed on the sme equipment did not show any change in behaviour.

Urmonas,

Was your speed loss only indicated by testing, or did you verify it in pictures too? I ask because it is well known that the blue sensitivity of one of my favorite tabular grain films sometimes acts like it has a yellow filter - which is a nice benefit - but it might throw off an open-shadow speed test depending on the direction of the sun, the amount of blue sky illumination, the time of day. Artificial light is "better" for tests in this sense.

Sorry must have misread your quote. It sounded as if the part of your reply about coming good meant that in recent times tabular films had achieved box speed for you and your process of exposing and developing but in fact this difference between conventional and tabular is still there.

So back to square one. I hope that as you work your way down all the suggestions one of them or a combo of them work

Best of luck

pentaxuser

The film speed loss was first noticed in pictures. I had used Delta 3200 for a few years, then suddenly I had very underexposed looking negatives. That's when my investigation began.

Urmonas said:

The film speed loss was first noticed in pictures. I had used Delta 3200 for a few years, then suddenly I had very underexposed looking negatives. That's when my investigation began.

Click to expand...

So at the risk of simply antagonising you further the situation was as follows: You had OK D3200 negatives for a few years then suddenly or over a short period at least you had underexposed looking negatives. I am unsure if this corrected itself or not? If it did then the investigation has at least the benefit of being academic which isn't to say unimportant.

Clearly something changed and if it wasn't a manufacturing defect which it wasn't as you stated yourself then something changed with your process. However what that change was, as often happens, is now lost to your memory.

I sympathise

pentaxuser

Gremlins, Leprechauns, or the CIA. They're always up to no good.