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Online Tool for curve plotting and analyzation

Overview Discussion
Update:



This new feature allows you to anaylze the tone reproduction curve. It shows Avg. Gradient and Avg. Mid-Tone gradient (Zone III to VII). It also overlays a Graph to see local gradient of each point.
 
All of these updates are incredible. Having an option for paper curves is great.

Three small requests related to the paper curve section:
1. Could you add a "Notes" option? Similar to the option under "Process Description"
2. Could you add the option to export paper curves as a separate PDF? It would be helpful in a reference binder when comparing papers.
3. Could you add a "Smooth" option for the curves?

Thanks again for making all these fantastic additions!
 

Done
 
Thanks for the tone reproduction four quadrants!
 
Bill Burk said:
Thanks for the tone reproduction four quadrants!
Click to expand...

they still dont line up all that well and it bugs me but for now its ok i think, please let me know should you find issues, have concerns or have questions regarding the tool
 
Update:
I added a menu that allows you to enter new tools that let you generate customized, nice record keeping templates for both printing and shooting. The cool thing being that you are able to customize them by ticking boxes.



 

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Wow this has come so far since I last visited it, great work! The Ux is super as well, not often you get web apps that look as good as they function.

For a newby tester, I'm stuck a bit on the relative curve measurement in that

1. Lets say my ref curve i've used hp5 @400 in xtol
2. Hypothetically lets pretend I used a sensitometer and my personal method gave me an personal EI on hp5 in xtol of iso 250
3. In this tool I never see this iso 250 so when I have a new curve how would I infer its speed?
4. Is it in effect giving me the speed that would match my reference speed/curve?

Does that make sense. If I don't have an absolute EI from my ref curve what information do new curves give me against the reference.

I have a stouffer 3rd step wedge so having no sensitometer this tool would make my life a lot easier

Thank you!
 
Using a standard developer (D-76 is close) you develop fresh name-brand film and develop it long enough that the contrast meets ASA parameters. Then you rely on the manufacturer speed guarantee so TMAX-400 for example would give 0.10 density above base plus fog at an exposure of -2.7 log meter candle seconds when developed like that.

Then compare this curve from a known film to an unknown film curve. For example if there is a shift to the left it means the unknown film responds more with less light so the unknown film is faster.
 
Great thank you, seems some trial and error at the beginning to get the reference sheet in the right ball park i.e to have the contrast meet asa parameters.

I would start at manufacturers time and developer recs and adjust based on my personal technique?

And reading your other posts Bill, I can use a diffused flash on a tripod and a light meter for a poor mans sensitometer? My bathroom has no windows
 
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You really want reliable consistent exposures even if they are arbitrary, it's the consistency that lets you see what you're doing. I'd permanently affix a spare flash, like a Vivitar 283 in manual mode aimed up at a piece of glass with the Stouffer scale taped on and a lid with a pad that presses the film to be tested against the scale. The overall idea is very much like a contact printer. Once you set it up, don't dismantle it and don't change the exposure setting.
 

Hey! Yes you are right. The best way to do it is to use a calibrated sensitometer. This would allow you to know the absolute lux second exposure received at the film plane. In the tool there is an option, that was suggested in this thread, to include a “calibration” based on a reference development. If you press the text “Calibration options” a dialog appears that allows you to enter a reference curve you developed to ISO conditions as closely as you can. Based on this curve all your other testing will be calibrated. (It uses the know luxs needed for the ISO curve you entered to “calibrate” the lux s axis of the tool and therefore your sensitometer output)
 
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