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Thread: Velvia 50 reciprocity correction

  1. #1

    Velvia 50 reciprocity correction

    Renon asked about this. Hope this is of interest.
    I have only recently started using Velvia 50 transparency film. My first roll was a disaster as I was using reciprocity factors worked out for negative films - result?: extreme overexposure. In fact all the frames were white.
    As some transparency films do not suffer from reciprocity failure, I then tried shoot without correction - result?: underexposure (although not too bad). So I did a bit of research and found a table of reciprocity correction values here:
    http://www.brucepercy.co.uk/blog/2008/05/06/reciprocity-chart-for-fuji-velvia-50-rvp/
    For longer exposures, I got info from another site. I cannot find it so apologies.
    Work out the exposure time for your pinhole/focal length combination (see:- Mr Pinhole's site). I have a Weston Master meter and I list the 'Light Values' against exposure times for my various cameras. Then multiply the indicated exposure time by the correction factor in the table below...

    Indicated exposure time Correction Factor Corrected exposure time
    4 seconds x 1.25 = 5 seconds
    8 s x1.5
    10 s x1.6
    16 s x 1.75
    20 s x 1.95
    25 s x 1.96
    32 s x 2.1
    40 s x 2.2
    50 s x 2.32
    64 s x 2.47
    1 min 21 s x 2.6
    1 min 42 s x 2.76
    2 min 8 s x 2.98
    3 min 22 s x 3.28

    The only thing you've got to watch is what you point your meter at. My advice is point at anything in shade that you want to see. Don't point at the sky unless you want cloud pictures. Another thing: Velvia 50 is supposed to get a green cast above a minute. I did not find this happened with 35mm Velvia 50 but did get green pictures with 120 roll film Velvia 50. I don't pretend to understand that!

    Finally, Velvia 100 ASA does not suffer as much from reciprocity. Provia doesn't have any reciprocity failure up to 10 minutes.

  2. #2
    500+ Posts Isis's Avatar
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    Velvia 50 reciprocity correction

    I have a a PDF which concurs with your post, but also has the colour correction filter required if you wish to correct that as well.
    For up to 20sec of time add a 5 CC Magenta filter, for 20sec to 120sec add a 10 CC filter and above 120sec use 20 CC Magenta filter.
    I would attach the PDF but its 114kb and I don't know how to make it smaller :-/

  3. #3

    Velvia 50 reciprocity correction

    John, many thanks for posting these data.

    Shane: Convert the pdf to a .jpg by conversion program or direct screen shot. then it should be easy to reduce the .jpg-file below 100k. Please post your data as well.

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    500+ Posts earlj's Avatar
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    Velvia 50 reciprocity correction

    Is this the table Shane?

    Attached files

  5. #5
    500+ Posts Isis's Avatar
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    Velvia 50 reciprocity correction

    Thanks Earl, thats it. I visited the link that Doc put up after a noticed it was the same anyway

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