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Stephen E. Sample |
10:02 15 Jun 07 |
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Philippe Bedfert |
1:44 16 Jun 07 |
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Stephen E. Sample |
10:49 16 Jun 07 |
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Steve Nicholls |
18:12 16 Jun 07 |
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Stephen E. Sample |
17:35 17 Jun 07 |
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Re: Personal Reference Speed Point |
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Steve Nicholls |
19:57 17 Jun 07 |
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Hi Steve,
It was excellent to talk with you on Skype.
We seem to have answered your questions in person but I will try to answer some of these points so the questions have continuity on the forum.
"I just didn't understand why the effective film speeds came in at 125 to 160 and the PSP as calculated by the Plotter program came in at 2.49. He showed me a number of other tests where the grey "Plotter ASA triangle" PSP was different from the blue 240 PSP. Some were above and some were below. I suggested that the calibration was incorrect. Fred didn't think so."
In the Articles section at the home page of the forum there is very good information on the PSP.
As an example I use two films that although rated at 100 and 200 iso both of them when tested correctly have an iso of 32 and 64 respectively. I have heard of some film/developer combinations doing as you indicate so for the time being I would shoot some film and trust the data. I think you will find Fred's calibration is correct.
"So I bought the Plotter program and again read the BTZS text to try and understand this better. I also put a PSP of 250 into my Plotter and got more reasonable film speed as outlined in my second post. Phil talks about recalibration by raising or lowering the test light source if you don't get a PSP of 240. Should I ask Fred to do a re-test?"
The PSP would I imagine be 2.4 if Fred is following Phil's setup. However ask Fred if he is using a different PSP with his system. Until you do your own testing whatever Fred's PSP is should be yours.
Until you actually shoot some film there is no need to re test.
"So, I'd appreciate the chance to talk more with you on this? My skype is very slow, because I only have a dial up connection. I'd be happy to call you worldwide, since it is pretty reasonable with my MCI card. Is Phil no longer monitoring this forum?"
Skype worked out well so after you shoot some film we can chat again and determine what to do -- if anything -- next.
I'm certain Phil is monitoring the forum but the wonderful thing is the way he has imparted his knowledge to so many on this forum that now there is always someone who has encountered your hurdle and crossed it with help from other happy BTZS user.
I know you will love the BTZS approach.
Steve
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Jorge Gasteazoro. |
16:52 18 Jun 07 |
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Stephen E. Sample |
9:59 19 Jun 07 |
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Jorge Gasteazoro. |
13:36 19 Jun 07 |
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Jeff Sylvia |
11:01 20 Oct 06 |
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