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  1. #11
    CPorter's Avatar
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    Thanks for that Bill. As per Ralph, the density readings for the "Input Data" tab are to be input as total density, so they include b+f, I sent him a message a while back asking specifically about that. This is because I have always graphed the curve based on net density too, that's how I learned in The Negative anyway----as per that resource, the b+f level is simply "printed through", it's not given any weight in reading the curve. Ralph's sheet includes it in the totality of the curve, which I find interesting to see. And in his literature, he specifically states to zero the densitometer without anything in the light path to enable reading fb+f of each sheet. I'm looking forward to Ralph's comments. My "net" density curves produce the same narrow range of resulting "N" development times, as they should.

    I have input "net" densities into the spread sheet and all that seems to differ, as expected, is the "cross hairs" indicating Dmin and Dmax drop to the actual Dmin and Dmax densities that were specified at the input tab. And at the "curve family" tab, one would see "net" density data indicated by a "level" red line at Dmin across all curves. This is opposed to a red line that would be slanted across all curves indicating the fluctuation of fb+f from 4 min to 16 min of development.

    On the individual curve tabs, using the total density, I placed a red line (the eyeball method) at the Dmin and Dmax densities, the cross hairs are above them and the difference between the two is the b+f level, which it differs with each sheet of course.

    My densitometer calibrates perfectly with it's calibration tablet and it indicates good linearity. So, I have no doubt that the curves as measured are right. But I question the high densities that I generated that have resulted in the curves shown, I believe something is amiss. If I have, as you say, clear +2 to -2 times, then there is the immediate question of why it is not indicated in the spreadsheet, at least in the way I am interpreting it anyway.
    Last edited by CPorter; 06-14-2012 at 08:47 AM. Click to view previous post history.

  2. #12
    Bill Burk's Avatar
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    Quote Originally Posted by CPorter View Post
    As per Ralph, the density readings for the "Input Data" tab are to be input as total density, so they include b+f
    ...
    I have input "net" densities into the spread sheet and ... at the "curve family" tab, one would see "net" density data indicated by a "level" red line at Dmin across all curves. This is opposed to a red line that would be slanted across all curves....
    Hi Chuck,

    That is fine to do it the way Ralph said. His spreadsheet is designed to take net densities.

    So that means my drawings with a straight lines across would ideally need to be a slanted lines as well.

    It may come down to a scenario where the curve fitting is difficult for the computer. Or maybe it illustrates the difference between the points selected to calculate "Contrast Index" versus "Average Gradient"
    Last edited by Bill Burk; 06-14-2012 at 10:02 AM. Click to view previous post history.

  3. #13
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    I've made a simple Time / Gradient graph in Excel using the data from Chuck's spreadsheet. While the rate of development isn't very steep, except for the 8 minute test, there doesn't appear to be a problem with the overall progression.

    Click image for larger version. 

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    Last edited by Stephen Benskin; 06-15-2012 at 11:01 PM. Click to view previous post history.

  4. #14
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    Quote Originally Posted by Stephen Benskin View Post
    I've made a simple Time / Gradient graph in Excel using the data from Chuck's spreadsheet. While the rate of development isn't very steep, except for the 8 minute test, there doesn't appear to be a problem with the overall progression.
    That's good to know, but I can't look at the "development compensation vs. development time" graph and think that it is right, at least at the moment.

  5. #15
    Stephen Benskin's Avatar
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    Chuck,

    If Ralph's spreadsheet calculates gradient in the way he describes in his book, it's base point is higher on the curve than what is normally used. Placing the base point higher on the curve will mostly factor in the straight-line portion of the curve and produce a higher gradient value than if the reading incorporated more of the toe. The two shorter timed tests of yours show a bit of a toe. There's a good chance this is the reason for higher than expected gradients. Like Bill indicated, if you measure the curves using different methodology like CI or average gradient with a 0.10 base point, you will get different results. I believe you might find them to be closer to what you are expecting.

  6. #16
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    Quote Originally Posted by Stephen Benskin View Post
    Chuck,

    If Ralph's spreadsheet calculates gradient in the way he describes in his book, it's base point is higher on the curve than what is normally used. Placing the base point higher on the curve will mostly factor in the straight-line portion of the curve and produce a higher gradient value than if the reading incorporated more of the toe. The two shorter timed tests of yours show a bit of a toe. There's a good chance this is the reason for higher than expected gradients. Like Bill indicated, if you measure the curves using different methodology like CI or average gradient with a 0.10 base point, you will get different results. I believe you might find them to be closer to what you are expecting.
    I thought of this last night and changed to 0.1 for Relative Dmin and 1.3 for Relative Dmax. The range of development compensations I got were from N-1 to just over N+1 as seen in the attachment, I admit, I don't understand why +2 and -2 for the final summary is not obtained, I guess it's over my head, IDK. Ralph mentions that a density range of 1.2 includes from the beginning of Zone II and to the end of Zone VIII (presumably for 0.17 and 1.37) ----since the zone locations are the mid-point of the zone, I see that as actually from Zone I 1/2 to Zone VIII 1/2. However, I don't know if that still holds when lowering the relative Dmin and Dmax values----0.1 and 1.3 are what I have traditionally used and they range from Zone I to Zone VIII.

    Also, I tooled around with the charts, just to add things graphically that help me when evaluating them, but that's just me.
    Attached Files

  7. #17
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    Hope you don't mind but I'm attaching a version in Open Document Format for those who haven't paid Microsoft to use spreadsheets. Let me know if you want it deleted.

    Lee

    Quote Originally Posted by CPorter View Post
    Also, I tooled around with the charts, just to add things graphically that help me when evaluating them, but that's just me.
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  8. #18
    Stephen Benskin's Avatar
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    Chuck, could you give 0.10 and 1.20 a try and see if there's any difference?

    How something is measured effects the results. This is one of the reasons why I tend to emphasis theory. Most of the time the variance in results will be inconsequential, but under certain circumstances there can be significant differences. The idea of the "best" methodology isn't about if it works or not, but that it produces the most consistent results under greatest number of situations. Take gamma for instance. It works very well for short toed, straight-line curves, but not with longer toed or curves without significant straight-line portions. Defining what is Normal development and the pluses and minuses is another example. Most methods work great for determining normal but begin to differ in results when working with the more extreme ranges of scenes encountered. Often times an alternative method can be superior to what is considered "the best" method under a certain set of conditions, but will fail under others. And this doesn't even begin to address how difficult it is to compare results from different people who use different methods.

    If you take a look at the gradient/time curve, you will notice your results don't exactly create a smooth arc. There's nothing wrong with that. There will always be slight variations in any test and this is what your results indicate, but if you add 0.02 to the 8 minute and subtract 0.02 to the 4 minute test, a more "realistic" depiction will result. From here, you can project the time you need for +2 and -2. I get about 18.5 for the gradient Ralph uses for +2 and maybe a little under 3 minutes for -2.

  9. #19
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    Quote Originally Posted by Lee L View Post
    Hope you don't mind but I'm attaching a version in Open Document Format for those who haven't paid Microsoft to use spreadsheets. Let me know if you want it deleted.

    Lee
    I've no problem with that..........

  10. #20
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    Not much difference there.....the off set is due to the sheet's formulas being set up for a NDR of 1.2, your suggestion was an NDR of 1.1. Maybe Ralph will chime in on it soon.
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