I'm graphing your data to double check it. Maybe Steve can do the same.
I started with the 6min graph, just because it was first in line, though, I could see the gamma was going to be low.
My first graph has some oddball things, so maybe there are some issues that need to be addressed.
1) You indicate "calibrated grayscale" but are the values you gave your actual densitometer readings from the grayscale? It would be hard to believe your densitometer matches that gray scale exactly. I use readings from the same densitometer on both X and Y axis. If you densitometer is far from the calibrated step wedge on a lot of the range, the curve might look better if you add a correction factor to each film step checked. (unless your densitometer agrees with every calibrated step).
2) I process TMY 2 for 6 minutes and get a gamma around 0.7. In your case the gamma was only 0.3. I know you used the steeper curves to fit the ASA triangle (per protocol) and Steve posted that ISO criteria for specific developers was relaxed, I think you may be using a developer combination or process that is not giving you full speed available from the film. Not all developers give the same 0.1 point when processed to match the ASA triangle.
Which dataset did you use to match the ASA triangle? I'll graph that one next.
3) The curve just 'looks odd' I have double checked all the points and I have graphed exactly the dataset below. Perhaps there is an error in data acquisition?
We can look at these speed numbers 'for educational purposes' but since this particular sample is not processed to a gamma you are likely to ever use in practice, I'll ignore those values.
The "W" point is a mathematical estimate of 0.3G point (likely similar to Delta-X point, maybe Steve can calculate the Delta-X on this dataset)
The ISO estimate is one stop to the right of the "W Speed" point
The inertia point is where the gamma line hits the X-axis
The ASA point is not indicated because the gamma is too low to fit the ASA triangle in this sample
The Delta-X point is not indicated but I may add that functionality to my spreadsheet later.
9/9/2011 TMY-2, 6 min, B+F 0.03
Last edited by ic-racer; 07-22-2012 at 10:54 AM. Click to view previous post history.