EXPOSURE CALULATION

Discussion in 'Pinhole Photography' started by Doyle Thomas, Apr 14, 2007.

  1. Doyle Thomas

    Doyle Thomas Member

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    Assume an aperture of f/166 and an ISO 100 then

    f/128 at 64 is the same (2/3 stop)
    f/90 at 120 is the same
    f/64 at 250 is the same
    f/32 at 500 is the same

    So if I set the meter at ISO 500 take a reading and set the stop at 32
    it should tell me exposure time - reciprocity at f/166?
     
  2. tpersin

    tpersin Member

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    i believe the simplest way is to set your meter for f16 and iso 100, multiply the resulting exposure value by 100, and then adjust for reciprocity...

    good luck!

    -tom
     
    Last edited by a moderator: Apr 14, 2007
  3. Doyle Thomas

    Doyle Thomas Member

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    Assume an aperture of f/166 and an ISO 100 then

    f/128 at 64 is the same (2/3 stop)
    f/90 at 120 is the same
    f/64 at 250 is the same
    f/32 at 500 is the same

    So if I set the meter at ISO 500 take a reading and set the stop at 32
    it should tell me exposure time - reciprocity at f/166?

    ok, now I have my Mind right. its:

    Assume an aperture of f/166 and an ISO 100 then

    f/128 at 64 is the same (2/3 stop)
    f/90 at 32 is the same
    f/64 at 16 is the same
    f/32 at 8 is the same

    So if I set the meter at ISO 8 take a reading and set the stop at 32
    it should tell me exposure time - reciprocity at f/166.
     
  4. Jim Noel

    Jim Noel Member

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    If the camera uses 35mm, 120 or 5x4 film, use Fuji Acros and forget about reciprocity calculations. That is the only film I use in pinholes of these sizes.
     
  5. Helen B

    Helen B Member

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    You missed out f/45:

    f/128 at 64 is the same (2/3 stop)
    f/90 at 32 is the same
    f/64 at 16 is the same
    f/45 at 8 is the same


    Best,
    Helen
     
  6. Doyle Thomas

    Doyle Thomas Member

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    Thanks!

    Assume an aperture of f/166 and an ISO 100 then

    f/128 at 64 is the same (2/3 stop)
    f/90 at 32 is the same
    f/64 at 16 is the same
    f/45 at 8 is the same
    f/32 at 4 is the same

    So if I set the meter at ISO 4 take a reading and set the stop at 32
    it should tell me exposure time - reciprocity at f/166.
     
  7. tpersin

    tpersin Member

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    or, another way, would be to set your meter for f16 and iso 100, multiply the resulting exposure value by 100, and then adjust for reciprocity...
    :wink: