Photography & Imaging

Intermediate

Exposure Reciprocity

Aperture, shutter and ISO trade off to keep exposure constant.

Formula

N^2 \propto \frac{ISO}{t}

Variables

NF-number

ISOSensor sensitivity

tShutter time (s)

Example

Halving shutter time? Open one stop or double ISO to compensate.

Did You Know?

The 'exposure triangle' of aperture, shutter and ISO is really just this reciprocity rule in action.

photography iso reciprocity

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More in Photography & Imaging

F-Number

Aperture f-number is focal length divided by aperture diameter.

Exposure Value (EV)

Combines aperture and shutter speed into one exposure figure.

Depth of Field (approx.)

Range of distances that appear acceptably sharp.

Hyperfocal Distance

Focus distance that keeps everything from H/2 to infinity sharp.

Lens Magnification

Image magnification from focal length and subject distance.

Angle of View

Field of view from sensor size and focal length.