[pure-silver] Re: Phototec vs. Digital Truth

The times listed in the Massive Dev Chart are a mixture of published data and user contributions. There is information about the way that conflicting information is resolved in the User's Guide which can be accessed via the menu on the left. In all cases the film manufacturer's published data is given preference over other contradictory data, unless there is a very clear case of the manufacturer's data being unreliable.
Although the times for Rollei Retro and Agfa APX should be identical, there have been changes made to the base of the Agfa film, and different times have been published by Agfa in different countries over the years. If you look at the current times published in the Massive Dev Chart for APX 100 and APX 400 in D-76, they are 9 minutes and 12 minutes respectively. There is an additional time of 10 minutes listed for APX 400, which together with the 9 minute time shown for APX 100 are both taken from publications prior to the change in the film base. When the film base was changed, Agfa released one final technical data sheet before the products were discontinued. This is publication F-PF-E4_en-Agfa2003, and shows the new time for APX 400 in D-76 as being 12 minutes. There is no data in this publication for APX 100 in D-76. Despite the published change, many users reported that the old times worked the same as before, so as always its up to each individual to run their own tests based on these starting points. Both the old and new times are shown in the Massive Dev Chart accordingly.
I haven't studied the Phototec chart in depth, but my first reaction to seeing it was that the calculations all appear to be based on one set of criteria, and as Martin Jangowski suggests, this could be very misleading. The Ilford time/temp chart, which a version of can be viewed from the left-hand menu of the Massive Dev Chart, offers the same kind of general information. I'd be a little concerned about directing people to Phototec's calculator as the implication is that the times generated by it are factual rather than just extrapolations. The times it shows might apply to linear development, but would not work with many combinations unless the specific contrast curve of each film and developer has been worked into the calculator. Somehow, I doubt that. 

--Jon Mided

Digitaltruth Photo
www.digitaltruth.com
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