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Phil,
I have done my TMAX film test, and I ran an initial test, with the result that ISO mark fell on 2.5 vs the desired 2.4 personal speed point. I repeated the film test, and adjusted the exposure, so that the two points fall almost exactly on the same point on the X-axis.(2.4)
The first test resulted in what seem to be normal looking EFS and dev charts.
The second, adjusted test resulted in the EFS charts looking a bit odd. First, the densitometric readings for the 11 minute and the 16 minute development tests run very close to one another. Some of the points for 11 minute curve overlap the 16 minute curve on the lower end.
Also, another observation, with the analysis curves for the second test, where the ISO point was adjusted to be 2.4, the 4 minute development curve, has no G or SBR number assigned to it. It has been extrapolated but no ID max has been assigned.
As far as the graphs are concerned, with the EFS/SBR graph, the EFS increases from SBR 11 to SBR 4.67, but decreases from SBR 4.67 to 4.33.
The same trend occurs with the G vs EFS graph. EFS increases from 0.3G to 0.85G, but decreases from 0.85G to 0.9G .
With the EFS/N number graph, the EFS increases from N-2.33 to N+1.33, but decreases from N+1.33 to N+1.66.
Is this an acceptable result? This does not occur with the first test, where the ISO mark fell on 2.5.
What is the effect of the ISO mark falling on 2.5 vs 2.4?
Any comments?
Fred B
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