Developing a mystery B&W film...

chrish

chrish

Chris H
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I have a film canister that I'm pretty sure contains either Ilford FP4 or HP5, but I'm not sure which. I would have exposed it at it's normal rated speed, 125 or 400 respectively.

Massive Dev chart says 10mins for one and 9 mins for the other using DDX. Should I split the difference and do 9.5 mins or should I trim some of the leader off and drop it in a little cup of developer to find out what film it really is?
 
The trimming off of a small section would make it clear exactly what you're dealing with. Then you'll be able to make a properly informed decision on how to process the rest of the film. However, the first section is highly likely to be completely over exposed as it will have been in daylight while the film was loaded into the camera, so snip off a small section at a time and process them one at a time until you can clearly see the manufacturer's codes on the edges.

Nick
 
I haven't use Ilford film in a long time but isn't there a color difference between the two films that could help identify which one it is...???
If not then what has been said would work...either develop a short section or split the developing times...

Hey look here a third option...^^^
 
I tend to make no difference and soup all film in one tank whenever the development times are closer than 25% - with your mere 10% you'd be well below the inevitable error margin you'll have in your inversion regime unless you use a motorized processor.

With my printing/scanning procedures, I tend to give it the longest time stated for any of the films - for manual printing to VC paper or for quality scanners it is generally better to push rather than pull (the latter will irrecoverably lose shadow detail if you are slightly underexposed, while good paper or scanners can salvage a fair lot of highlight detail). But on scanners with a restricted contrast range, soft, thin negatives are the way to go, and there, half way or the shortest time will deliver better results - at least if you are confident you did not underexpose as well.
 
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Thats only a 10% difference thereabouts. It'll make only a small difference. Just use the shorter time of 9 minutes. If that was the wrong choice the neg will only be a tad soft which is easily recoverable without noticing either digitally or wet printing.
 
One minute difference in developing time? If you developed the leader, what would you be looking for? If it's the 10 minute one, the leader would be black by 9 minutes anyway.

So yeah, develop for 9 to 9.5 minutes and just correct the prints (or scans if that's what you do.) A half to 1 minute loss won't be that much different.
 
Chris by developing the leader he is looking to identify which film it is not gauge correct exposure time. To the OP how important is the contents of the film? For me that would determine whether I made sure I used a precise dev time or could afford to be a bit more casual.
 
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