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

[Ian Grant]

Ian Grant submitted a new resource:

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

Apertures in 1/3 stops

0.7 0.8 0.9 1.0 1.1 1.2 1.4 1.6 1.8 2 2.2 2.5 2.8 3.2 3.5 4 4.5 5.0 5.6 6.3 7.1 8 9 10 1 13 14 16 18 20 22 25 29 32 36 40 45 51 57 64 72 80 90


Shutter speeds in 1/3 stops (seconds)

2 1.6 1.3 1 0.8 0.6 1/2 0.4 0.3 1/4 1/5 1/6 1/8 1/10 1/13 1/15 1/20 1/25 1/30 1/40 1/50 1/60 1/80 1/100...

Read more about this resource...

 

[martin henson]

Thank you Mr Grant, very useful numbers

Regards
Martin

 

[Emmanuel Bigler]

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.

 

[Emmanuel Bigler]

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