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> Ilford Reciprocity Calculation |
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#1
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Ilford Reciprocity Calculation
Ilford have released a new recommendation for reciprocity calculation. It is in the form of a pdf and has factors for each film so that you can calculate the corrected time instead of trying to read it from a graph. Instructions are included on the sheet.
It can be found at https://www.ilfordphoto.com/wp/wp-co...mpensation.pdf Bill |
#2
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Unfortunately the link doesn't work for me, neither does the Google search link. So perhaps something is going on with that document at Ilfords end?
__________________
MartyNL “Reaching a creative state of mind thru positive action is considered preferable to waiting for inspiration.” - Minor White, 1950 |
#3
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Worked for me and I saved it as an image in pictures.
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#4
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Try again, Marty. It just worked for me there.
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#5
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I've attached the document from Ilford.
Mike |
#6
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Just checked and it is working for me.
Bill |
#7
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Yes working fine now. Thank you.
__________________
MartyNL “Reaching a creative state of mind thru positive action is considered preferable to waiting for inspiration.” - Minor White, 1950 |
#8
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Here's a statement (slightly edited by me) from Ilford about this release:
The charts currently in all our individual film fact sheets are calculated with the same method using a factor of 1.48. The people who came up with this factor left the company many years ago so I have no idea how it was derived. It was because of our customers questioning this factor that we did the work. I was curious to see how this new pdf compares with the factor given for my two favorite films, HP5+ and FP4+, so I used MS Excel to plot the readings from the curve shown in the many film data sheets and find a best-fit curve through those readings, then plotted the results yielded by the new pdf for the comparison. I was able to confirm the factor 1.48 very closely. The attached final plot shows all my results. I think the pdf is the best way for Ilford to present their results, as it allows one to either plot curves to put in a field notebook OR tabulate the corrections for preferred films to place on a light meter. Obviously, the reciprocity corrections required now are much less vigorous than Ilford's previous recommendations. Last edited by Jerry Bodine; 1st September 2017 at 05:28 PM. |
#9
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Thank you for posting this, Bill. I made up a table with exposure corrections for my three mostly used films, which will find a place in my bag.
Frank |
#10
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For some years I have been using a table produced by Les McLean which he found to work for him and I have found to work for me. However Les's values start off similar to Ilfords new values at two seconds but Ilford's values become less than Les's upto two minutes exposure by less than half for FP4 and HP5. It would be interesting to hear how anyone finds how Ilford's new values work.
Tony |
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