Complete the account of the exposure controls.
A stop is a factor of ______ in the light. The f-number is the focal length divided by the diameter of the entrance ______, and the series climbs by the square root of two because light passes through an ______. The failure of the reciprocity law at very long exposures is a property of the individual ______ and is published for each one.
Word bank: two · pupil · area · emulsion · four · shutter
Hints
- The third blank explains why the series is not a simple doubling.
- The last blank is why there is no universal correction table.
Show the answer
A stop is a factor of two in the light. The f-number is the focal length divided by the diameter of the entrance pupil, and the series climbs by the square root of two because light passes through an area. The failure of the reciprocity law at very long exposures is a property of the individual emulsion and is published for each one.
The third blank is the one that makes the series memorable rather than arbitrary. Halving an area means dividing a diameter by the square root of two, so the f-numbers are just 1 multiplied by 1.414 again and again, rounded for printing on a barrel.
Practise Aperture, Shutter and Sensitivity
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More questions on Aperture, Shutter and Sensitivity
- A photographer opens the aperture by two stops and shortens the shutter by two stops. The negative density…
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- How many whole stops separate f/2 from f/11?
- Arrange these shutter speeds from the longest exposure to the shortest.
- By what factor does the light reaching the film fall when the aperture is closed from f/4 to f/8?
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