Apertures, Shutter Speeds and Film speeds in 1/3 stops.

1/3 stop increments

  1. Ian Grant

    Ian Grant Active Member Registered User

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    Ian Grant submitted a new resource:

    Apertures, Shutter Speeds and Film speeds in 1/3 stops. - 1/3 stop increments

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  2. martin henson

    martin henson Admin Staff Member Registered User

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    Thank you Mr Grant, very useful numbers

    Regards
    Martin
     
  3. Emmanuel Bigler

    Emmanuel Bigler New Member Registered User

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    Thanks to Ian Grant for the chart
    In addition, please find as downloadable jpeg image, a bar-chart showing the correspondence between the old series of speeds (e.g. on certain Compur shutters)
    1 1/2 1/5 1/10 1/20 1/50 1/100 1/200 1/400
    and the modern standard series
    1/2 1/4 1/8 1/5 1/30 1/60 1/125 1/250 1/500
    https://www.flickr.com/photos/43175600@N00/412475261
    The old series differs only by 1/3 of a stop to the closest value of the modern series.
     
  4. Emmanuel Bigler

    Emmanuel Bigler New Member Registered User

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    Another useful tool: a circular slide rule, a pdf document to download, ready to print and glue on cardboard, to compute at a glance the exposure values (EV) by 1/3 of a f-stop, when you are using very small apertures (e.g. f/500 with a pinhole camera) or very long exposure times (e.g. if you use a dark neutral grey filter).

    This slide rule, of course, is not an exposure meter (except if you consider that the "sunny-16 rule" is your favourite metering system ;) ) and does not take into account reciprocity failure, which has to be added; you should increase exposure times according to the film manufacturer's specifications for non-reciprocity.

    http://bigler.blog.free.fr/public/docs-en-pdf/2018-08-10-EV-circular-slide-rule_instructions.pdf
     

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