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#1
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Old v New ID11
I have been doing yet more Beyond the Zone System tests in sheets of HP5 in ID11 at 1+1.
I had Fred Newman of the View Camera Store expose me a block of 25 sheets of HP5 using a calibrated step wedge and his calibrated light source. Once they were with me, I proceeded to develop the sheets of film using a Jobo CPP and Jobo 3010 Expert film tanks. The original purpose was to produce a new series of film speeds and development times for HP5 but using continuous agitation using a rotary method. The ID11 I was using as the developer was about 3 to 4 months old, having been stored in PET bottles which were filled with Protectan gas before filling. The ID11 was the same almost colourless pale straw that my ID11 always is when new. I then decided to repeat the whole exercise using some freshly made up ID11 - 3 to 4 days old. The main purpose was to see how repeatable my development process was. I sent the resulting negatives back to Fred and he measured them on a Densitometer and emailed me the results back for me to do my BTZS analysis. The results are surprisingly consistent - the two sets of negatives were measured to be almost exactly the same. While this is reassuring it is also hardly surprising - using a Jobo takes almost all the human variation out of the development process - all the operator has to do is pour the chemicals in and drain them out at the correct time. However, there was one small difference between the two sets of results and that was at the higher set of density steps during the 22 minute development cycle. Here the new developer gave slightly higher density readings at the denser film steps. I have rationalised the results to the new ID11 had very slightly more potency than the old ID11 but this was only apparent when the developer was pushed to its absolute maximum. I've seen this effect in print developers as they get older - it is the density of the deep blacks on the print which are the first to go as the develop approaches exhaustion. I have attached the two sets of measured results for comparison. Has anyone else any similar experiences ? Martin |
#2
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I have never measured that scientifically, but I have been using ID11 stock, and some I mixed last August, and I can't see any difference between film's developed in August to one I developed 2 days ago in the same batch
Richard
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#3
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My understanding is that ID11 only increases in activity over the first couple of days after mixing. I don't profess to understand the chemistry but my experience (before I knew any better) was that newly-mixed home-brewed ID11 (to Ilford's published recipe) gave thin negs if used straight away. Results after a few days with the same film and dev combination were OK. There's nothing about this on Ilford's official data for their own product so I suspect they've tweaked the recipe to give consistent results. This would explain Martin's test results.
Last edited by Rob Archer; 10th May 2021 at 06:51 PM. |
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