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Re: Plus X Aerographic Film Testing

Phil Davis

7:48 12 Apr 05

Mike --

We can't do a complete analysis on a single curve but the fact that it happens to have a G-bar value of 0.62 (approximating the ISO standard) is helpful. Because of that we can place the "ISO reference" speed point at a density level of 0.1 over B+F in accordance with the Standard. Since your B+F is 0.14 the ISO reference density is therefore 0.24. Referring to the "Data" tab in the Plotter it appears that density 0.24 (y-axis) corresponds to about 1.8 (between steps 12 and 13) on the x-axis. That's 2 stops (0.6) slower than your assumed speed which would make it somewhere around 25 to 32.

I'd suggest doing a complete test at EV 5.0, assigning the film an "ISO" rating of 25 in the Plotter. The Plotter will then determine the effective speeds for you.

Don't waste even a minute worrying about what Kodak says the speed is; at best their recommendation is a ballpark starting point for personal speed determination and in this case they're not even close. This dramatic speed discrepancy plus the unusually high fog level suggest that this may be old film. You might be able to lower the fog level by restraining the developer but that will be likely to decrease the effective film speed even further.