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Moon Exposure Calculator (Looney 11 Rule)

Get the right camera settings to photograph the Moon with the Looney 11 rule: shutter speed for your ISO and aperture, adjusted for the Moon phase and haze, with the nearest standard speed.

ISO

Aperture (f-number)

Moon phase

Sky

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How it works

Looney 11: full moon at f/11 → shutter = 1 ÷ ISO · other apertures: t = (1 ÷ ISO) × (N ÷ 11)² · × 2 for each stop of phase or haze (gibbous +1, quarter +2, crescent +3, thin crescent +4, haze or low Moon +1)

The Moon is a sunlit rock, so it needs a daylight exposure, not a night one — which is why automatic metering against a black sky turns it into a white blob. The Looney 11 rule, a cousin of Sunny 16, says that at f/11 the shutter speed for a full moon is the reciprocal of the ISO. Partial phases are dimmer near the terminator and need more exposure, roughly one stop per step from full to thin crescent, and haze or a low Moon seen through more atmosphere costs about another stop. Bracket a stop either way and check the histogram.

Worked example

A clear full moon at ISO 100 and f/11 needs 1/100 s (EV 13.56). At f/8 the same exposure is about 1/189 s (set 1/200 s), and a half moon would need 2 stops more: 1/25 s at f/11.

Sources: Wikipedia — Looney 11 rule · Wikipedia — Sunny 16 rule

Frequently asked questions

What are the best settings for photographing the Moon?

Start with the Looney 11 rule: f/11 and a shutter speed of 1/ISO for a full moon — ISO 100 at 1/100 s or ISO 200 at 1/200 s. Use manual mode and spot metering or a histogram check.

Why is my Moon photo overexposed?

The camera meters the mostly black frame and brightens everything, so the Moon blows out. Switch to manual exposure with Looney 11 settings, or dial in −2 to −3 stops of exposure compensation.

Does the Moon phase change the exposure?

Yes. A crescent or half moon is dimmer than a full moon, about one stop per phase step, and the dark edge near the terminator needs more exposure still.

What focal length do I need?

The Moon is about 0.5° wide, so its image is about focal length ÷ 110: 4.5 mm on the sensor at 500 mm. See the Moon size on sensor calculator.

Related calculators

Sunny 16 Exposure Calculator

Meter-free daylight exposure: the Sunny 16 rule gives you a shutter speed for any ISO, aperture and sky condition.

Moon & Planet Size on Camera Sensor Calculator

How large the Moon, Sun or a planet will appear on your camera sensor at a given focal length — pixels and millimetres across, share of the frame, the focal length for a frame-filling Moon and a safe shutter speed to freeze its drift.

Equivalent Exposure Calculator

Keep the same exposure when you change aperture, shutter speed or ISO: enter your metered settings, change two of them and get the third, with the nearest standard setting and the stops each change adds.

Moon Phase Calculator

Find the Moon’s phase for any date and time in your time zone: the illuminated percentage, the Moon’s age, which side is lit, its distance and zodiac sign, the next new, quarter and full moons, and a day-by-day moon calendar for the month — using Meeus’s astronomical algorithms.

Exposure Value Calculator

Convert aperture, shutter speed and ISO into a single exposure value (EV) — and see the lighting condition it corresponds to.

This calculator is for educational purposes. Double-check important results before acting on them.