Developing rolls of few frames

[btgc]

I need to run some tests, using short rolls of 6-12 exposures. I've never developed film shorter than 36exp so I started to think if I can reduce concentration of developer.
From what I have read I realize I can safely keep same concentration (say, 13ml of syrup to 337ml of water) as for 36exp roll and souping short roll for same time it will not be overdeveloped, developer just will be less exhausted than in case of 36exp roll.

Question is if I can reduce concentration, keep same time and have same results? Behind my math stays fact 12exp roll has 3 times (I'm rounding up) smaller surface than 36exp roll so...3 times less syrup? 2 times less, for safety? I read Ilford manual on developers, googled but still no clear idea.

P.S. Am I cheap? Yes 🙂 If if this is false economy, I can live with that. I just don't want to throw away stuff in excess.

 

[ibcrewin]

Well you still have to make enough to cover the film in the spool. What kind of tests are you running? Your method is not scientific if you're chaning dilutions etc of the developer, when you're testing different ei's.. kwim?

maybe you can use the same 300ml of developer 3x for 12frames strips, or 6x for 6 frame strips.

 

[btgc]

Well you still have to make enough to cover the film in the spool. What kind of tests are you running? Your method is not scientific if you're chaning dilutions etc of the developer, when you're testing different ei's.. kwim?

maybe you can use the same 300ml of developer 3x for 12frames strips, or 6x for 6 frame strips.

Note, I'm talking about concentration not volume. Tests are targeted at flash work, development isn't subject of tests (not planned, at least). ISO will be same during all tests, EI will change slightly.

 

[MartinP]

If you are able to shoot the different tests on the same day, then simply re-use the developer until the nominal 36 exposures have been used eg. three short rolls or whatever. However, it might be wise to make up more than the minimum amount for the tank in order to minimise the small (but real) reduction in effectiveness. It all depends on exactly what you are trying to test really.

Alternatively, there are manufacturers guidelines for the re-use of such standard developers as ID11, D76 or DDX, based on the amount of film through the solution. With those developers you re-use the same litre (or other 'large' volume) of developer and make adjustments to the time as recommended. Again, this is less precise than you might need, as a roll of night shots will need less development activity than a roll of sunlit ski-pictures. If everything is 'average' then you will be good to go, with high confidence that your tests are valid.

Edit: simultaneous posts with OP

 

[ibcrewin]

Note, I'm talking about concentration not volume. Tests are targeted at flash work, development isn't subject of tests (not planned, at least). ISO will be same during all tests, EI will change slightly.

I see.. So why not shoot all the flash shots on the same roll? I'm with martin, use the developer until you've reached the 36 frame limit.

 

[btgc]

I plan to change technique basing on results from previous tests, that's reason why I'm planning shorter rolls than regular 36exp. I'm not sure all tests may happen on same day, though.

Currently you both advice to reuse developer and compensate dev time. Now it gets interesting. I hope someone dealing with lots of short rolls will step into discussion - not that I'm unhappy with your suggestion but if tests are spanning timeframe of several days I think fresh soup every time would be better.

 

[MartinP]

Oops, I now see that you aren't testing the film but rather the flash system. If the exposures and subjects are all very consistent then make up a litre of D76/ID11 and re-use it. The capacity (with time compensation) is ten rolls of 35mm, and the stock lasts for long enough.

 

[pufy]

Note, I'm talking about concentration not volume. Tests are targeted at flash work, development isn't subject of tests (not planned, at least). ISO will be same during all tests, EI will change slightly.

No, you can not change concentration and have the same results.

Dragos

 

[btgc]

No, you can not change concentration and have the same results.

Not only concentration is going to change - also film to be processed will be less. See, 36exp roll has surface about 3 times larger than 12exp roll.

make up a litre of D76/ID11 and re-use it. The capacity (with time compensation) is ten rolls of 35mm, and the stock lasts for long enough.

Right, I should have mentioned I'm using one-shot Ilford LC29. It can be reused with time compensation. If I put it back into bottle without much air over liquid and seal it well, it could be used next day, probably.

 

[bensyverson]

You don't change concentration based on film length... It has nothing to do with surface area. It has to do with volume.

 

[btgc]

Finally I figured this out - concentration can be weaker but then time has to be longer. In a word, certain concentration has certain "pulling power" - just like plane need certain power to take off, also developer need certain concentration to do job. After short roll soup will still have more remaining "power" than after long roll, but this power isn't like in....freshly charged battery, it's more like after sitting in a drawer for a week.

Most important is - as I normally develop using certain concentration and times, it's just not practical to change variables during tests. After all, we aren't talking about hundreds of short rolls or large bucket of developer 🙂 Maybe ten rolls or that.

Thanks all!