Exposure Calculator

What Is Exposure Value?

Exposure value (EV) is a single number that describes how bright a scene is and whether your camera settings can capture it correctly. It combines aperture, shutter speed, and ISO into one comparable scale. A higher EV means brighter light; a lower EV means darker conditions like night skies or candle-lit rooms.

Exposure Value Formula

The standard EV formula at a given ISO is:

$$\mathrm{EV} = \log_2\left(\frac{100 \cdot f^2}{\mathrm{ISO} \cdot t}\right)$$

Where $f$ is the f-number (aperture), ISO is sensor sensitivity, and $t$ is shutter speed in seconds. For example, f/8, ISO 200, and 1/500 s gives EV about 14, which matches bright hazy sun or rainbow conditions.

Frequently Asked Questions

What does EV 0 mean?

EV 0 typically matches dim ambient artificial lighting indoors. It is a reference point on the logarithmic scale, not an absolute brightness in lux.

Why use log base 2?

Each full EV step doubles or halves the light reaching the sensor. Log base 2 turns those doublings into simple integer steps that photographers can trade between aperture, shutter, and ISO.

Can I compare two camera setups with EV?

Yes. If two combinations produce the same EV at the same ISO, they should give equivalent exposure brightness before creative effects like depth of field.

Does EV include ISO?

Yes. The formula uses ISO directly. Doubling ISO raises EV by one stop if aperture and shutter stay fixed.

What EV do I need for the Milky Way?

Deep star fields are around EV -7. You will need very long exposures, wide apertures, and high ISO with a stable tripod.

Is sunny 16 the same as EV 15?

Close. The sunny 16 rule (f/16, 1/ISO shutter) lands near EV 15 in bright direct sun, which matches the classic daylight reference.

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What Is Exposure Value?

Exposure Value Formula

Frequently Asked Questions

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