Compensating for less film in the developer

[Ulophot]

Years ago, I had queried Ilford about how much fully exposed -- i.e., out of camera in the daylight -- film was equivalent to a given number of average exposures (call it a frame of all Zone IV or V if you like). My question derived from exposure and development tests using very short rolls of 35mm film, say, 6 frames as opposed to 36, and trying to keep developer activity as it would be were I using a full roll, as I would be after testing finished. I included a strip of so many fully exposed frames in the reel along with my test exposures. Another way to put it would be: how many fully exposed frames use up about the same developer activity as 36 average exposures?
I am in the same situation now, retesting with a new developer after a dozen years of photographic hiatus. I'll be using short sections of 35mm, as well as 2 sheets in a Jobo rotary tank that holds 12. In the latter case, I can decrease developer volume somewhat (I'll have to look back at my notes).
In any case, I would like to know if anyone has a good rule of thumb for equivalence: square inches of fully exposed film to "average." It may be 1:4, 1:6; I can't recall. I'm not trying to split hairs here, just get a little closer to eliminating one more variable in modest amounts of developer.

 

[Trask]

I often develop short rolls I've cut from bulk film, and have thought some about this issue. In my mind, it comes down to the interface where the film meets the developer. To wit: if there is enough developer in the tank to develop 36 exposures, does that developer's "development maximum capacity" somehow over develop the less-than-36 exposures in the tank? I would think that there might be a difference between the development of 36 exposures vs 6 exposures in one case: where you are using a highly dilute developer that would, by design, be fully exhausted at complete development of the 36 exposures, but would not be fully exhausted in developing 6 exposures. I imagine that in 98% of our developing our films, that is not the case -- I'd bet that the 220ml of D-76 I can use in a small Nikor tank to develop 36 exposures would still have significant development potential remaining. Which means, in my theory, that each frame was fully developed, as would be the 6 exposures in the short roll.

An alternative way of thinking about it: rather than thinking of 36 exposures vs 6 exposures in a limited amount of developer, think about putting a reel of 36 exposures in, say, five gallons of D-76. Would those exposures be any different from those developed in 300-400ml? I doubt it, as what really counts is the nature of the developer in immediate contact with the film. Putting aside some slight and hard to quantify bromide build up and other factors, I bet your 36 exposures and 6 exposures will be indistinguishable.

 

[M Carter]

My belief is that it's all about the ratio, and having enough soup to cover the film. When I do a bunch of anal zone system tests for film and developer combos, if I run a strip of 6 frames - and I can bottle up that developer in a bottle without much air space - and if I can run more frames the same day - I re-use it. I assume the developer "expected" 36 frames and only worked on 6. (when I do such tests, I blow-dry off the film and go straight to fiber prints at 2.5 filtration and base my results on final output).

 

[darkroommike]

Unless your normal processing takes a longer roll of film close to developer exhaustion I doubt you'll see much difference when processing a shorter roll.

 

[pdeeh]

I'm sorry, but the words "anal zone" have made this thread impossible.

 

[markbarendt]

Any normal batch of developer, prepared and used per the manufacturers directions should have the appropriate concentration of chemicals and capacity to develop a given amount of film regardless of exposure.

A 6 frame short roll is probably close to 1/5th the length of a 36 frame roll (not 1/6th) because of the leader. When that short roll is developed the concentration is changed and capacity reduced.

M Carters second batch of film in that morning's soup would theoretically come out slightly less dense. It may not be enough different to be significant, but it will be different.

Technically to eliminate the difference one could a) agitate more, b) increase temp, c) increase time, d) use a fresh batch of developer, or e) use a replenishment regime.

Of those options d and e provide the most consistent results. Conversely a, b, and c, (though often well within the tolerances of our own systems) are going to be based on good guesses and will work differently than the previous run because we don't really know how much the chemical mix changes during any given run.

 

[Gerald C Koch]

The OP is overly concerned with trifles. Development is subject to several factors and trying to control every one precisely is an impossible task. When a manufacturer like Kodak or Ilford says that one of their films requires X number of minutes at 20C this value is based on a large sampling of results. So even their values are an approximation.

 

[pentaxuser]

I'm sorry, but the words "anal zone" have made this thread impossible.

We are getting dangerously close to a Carry-On APUG scenario ....Ooh Matron. Sorry that won't mean anything to our U.S. members or indeed non British APUGers but on a serious level, I wonder what is meant by "anal" as in "anal zone system tests for film"?

It may be the two countries divided by a common language problem. Can you enlighten this Brit, M Carter? Thanks

pentaxuser

 

[Sirius Glass]

A roll of 36 exposures of 35mm film us approximately 80 in2. Use ratios to determine the developer usage.

Number of exposures *100% = percentage of developer used
36
This not only works with Ilford film, it ever works for Kodak film.