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  1. #11
    BradS's Avatar
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    Quote Originally Posted by Donald Miller
    Since most use light meters to determine exposure, it is probably not information that is published.

    Fred Picker (founder of Zone VI) used a system called the Key Day system. A variation of the Sunny F 16 rule. His system went like this. If there were no clouds...bright sunlight then F16 or equivalent EV was the exposure for the day. For a light overcast day open a stop. For heavy overcast open another stop. For open shade open another stop. For deep shade open another stop.
    ah, but....this is exactly the Sunny 16 rule.

  2. #12
    Jim Jones's Avatar
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    Quote Originally Posted by rhys
    . . . There are formulae around to calculate Lunar and Solar positions at various times in the year. I must find out about that next :d
    I use U.S.Naval Observatory and print out the data I expect to use.

  3. #13
    Andy K's Avatar
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    Years ago I made a sunny sixteen slide rule. See here and here. I no longer have the full tables but you may be able to enhance on the information on my sliderule.


    -----------My Flickr-----------
    Anáil nathrach, ortha bháis is beatha, do chéal déanaimh.

  4. #14
    Jim Jones's Avatar
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    Quote Originally Posted by Donald Miller
    . . . Edward Weston, so far as I know, never used a light meter and made some incredible images.
    Charis Wilson mentions Weston measuring light, and photographs of him show what certainly looks like a Weston Master meter case on his belt. He seemed to take pride in his simple equipment and techniques, but used whatever it took to make the photograph right.

  5. #15
    Dave Miller's Avatar
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    Ed Buffaloe has a article on this subject that may assist.

    http://unblinkingeye.com/Articles/Ex.../exposure.html
    Regards Dave.

    An English Eye


  6. #16
    Blighty's Avatar
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    Hmm. This is getting a bit eerie! I was just about to post a question asking exactly the same thing (sunny sixteen etc.) Last week I was just about to ask about processing old films but someone pre empted me. Maybe higher forces at work here!
    Norman is an island.Time and tide wait for Norman.

  7. #17

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    Quote Originally Posted by BradS
    ah, but....this is exactly the Sunny 16 rule.
    No this is different for the following reason...the sunny 16 rule uses the published box speed of the film. The Picker method determines the EI as it applies to your equipment and materials.

  8. #18
    Stephen Benskin's Avatar
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    Loyd Jones and H.R. Condit wrote a paper for the Journal of the Optical Society of America in 1948 titled Sunlight and Skylight as Determinants of Photographic Exposure. It was published in two parts and combined is about 80 pages. It would not be an exageration to say this is the ultimate source for everything discussed on this thread. In addition, I don't think it's a coincidence that the first ASA standard of light meters was also release the same year this paper was published and that Jones was the chair on the light meter committee.

    On the subject of light meters, the basic balanced exposure equation is:

    A^2/T = BxS/K

    where
    A= aperture
    T = shutter
    B = luminance in footlambarts
    S = film speed
    K = constant

    Here's the Sunny 16 example

    16^2/ 1/125 = 297x125 / 1.16

    this reduces down to

    256/256 = 1

  9. #19

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    Quote Originally Posted by Stephen Benskin
    Loyd Jones and H.R. Condit wrote a paper for the Journal of the Optical Society of America in 1948 titled Sunlight and Skylight as Determinants of Photographic Exposure. It was published in two parts and combined is about 80 pages. It would not be an exageration to say this is the ultimate source for everything discussed on this thread. In addition, I don't think it's a coincidence that the first ASA standard of light meters was also release the same year this paper was published and that Jones was the chair on the light meter committee.

    On the subject of light meters, the basic balanced exposure equation is:

    A^2/T = BxS/K

    where
    A= aperture
    T = shutter
    B = luminance in footlambarts
    S = film speed
    K = constant

    Here's the Sunny 16 example

    16/ 1/125 = 297x125 / 1.16

    this reduces down to

    256/256 = 1
    Stephen,

    Where would one find the paper that you mentioned? Thanks for sharing this information.

  10. #20

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    Quote Originally Posted by Andy K
    Years ago I made a sunny sixteen slide rule. See here and here. I no longer have the full tables but you may be able to enhance on the information on my sliderule.
    Andy, Thanks for posting this.

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