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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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Steve Nicholls |
19:57 17 Jun 07 |
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Re: Personal Reference Speed Point |
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Jorge Gasteazoro. |
16:52 18 Jun 07 |
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As I understand it the VCS exposes the negatives, sends the negatives for you to develop and then you send them back for reading and plotting. Since the VCS has calibrated according to Phil's test they have their PSP at 2.4 and this is why their results for film speed came back to you a bit higher. In essence 1/3 of a stop higher.
You did the right thing by moving the PSP to 2.5, this just means that IN YOUR developing process you have a variable that is different than those from Phil's examples and calibration. This could be a higher temperature, difference in mixing the developer etc.
When people talk about calibrating the system, they are simply taking one of Phil's examples and trying to replicate it. For example, I did TMY in XTOL 1+1. I changed exposures in my sensitometer until I got results that were equal to Phil's at the same temp and developer strenght.
In the end, the proof is in the pudding, you will have to assess the resulting negatives and see if the results you got by moving the PSP give you acceptable negatives.
OTOH, trying to mix BTZS and the ZS is a recipe for disaster. I beleive that what you will try to do is to take spot readings and then use the formula in the index of the book to convert to SBRs. I tried it this way and it was a source of frustration, not to mention that I think Phil has reqorked the formula in following editions of the book. You will find that by the time you run the calculation, light has changed and you will have to take meter readings again, making this and endless exercise.
My advice would be to learn how to do the incident metering technique, it is actually faster than spot readings and once you become capable in it you will never go back to spot metering.
I wish you luck,
Jorge.
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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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