Moon Exposure Calculator

Enter your ISO, aperture, and moon phase to calculate the ideal shutter speed, exposure value, and scene luminance for lunar photography.

Created by Luis GonzalezLast updated: May 9, 2026

How to Use This Calculator

1
Enter ISO
Input your camera's sensor sensitivity (e.g., 100, 200, 400), which affects exposure and noise.
2
Specify Aperture (f-number)
Provide the f-number of your lens aperture (e.g., f/8, f/11), controlling depth of field and light intake.
3
Select Moon Phase
Choose the current phase of the moon (Full Moon, Gibbous, Quarter, Crescent, Thin Crescent) from the dropdown menu.
4
Review Your Results
The calculator will display the recommended shutter speed, Exposure Value (EV), scene luminance, and aperture f-stop for optimal moon photography.

Example Calculation

A photographer wants to capture a full moon using ISO 100 and an aperture of f/8.

ISO

100

Aperture (f-number) (f/)

Moon Phase

Full Moon

Results

1/2344 s

Tips

Use a Tripod and Remote Shutter

For sharp moon photos, especially with telephoto lenses, use a sturdy tripod and a remote shutter release (or 2-second timer). This minimizes camera shake and ensures crisp details in the lunar surface.

Focus Manually for Sharpness

Autofocus often struggles with the moon. Switch to manual focus, zoom in on the moon in Live View, and carefully adjust for the sharpest possible image. The moon is far enough away that infinity focus is generally appropriate.

Bracket Your Exposures

Even with the calculator, lighting conditions can vary. Take several shots at slightly different shutter speeds (e.g., -1 EV, 0 EV, +1 EV) to ensure you capture all the lunar details without blowing out highlights or losing shadow information.

Achieving Perfect Lunar Shots with the Moon Exposure Calculator

The Moon Exposure Calculator is a specialized tool designed to help photographers capture stunning images of Earth's natural satellite. By considering ISO, aperture, and the moon's current phase, it provides optimal shutter speed and Exposure Value (EV) recommendations. This precision is crucial because the moon's brightness varies dramatically across its phases, from the intensely luminous full moon to the delicate thin crescent. For instance, the classic "Looney 11" rule suggests f/11 at 1/ISO for a full moon, while a crescent moon requires several stops more exposure to capture its subtle details without underexposing.

Capturing the Moon's Detail Across Phases

The moon's phase is the most critical factor influencing its apparent brightness and contrast, directly dictating the required exposure settings. A full moon can be incredibly bright, comparable to a daylight scene in terms of reflected light, sometimes reaching over 100,000 lux. This extreme brightness demands fast shutter speeds and smaller apertures. Conversely, a thin crescent moon, with only a sliver illuminated, is significantly dimmer, requiring much longer exposures or wider apertures to gather enough light. The "Looney 11" rule (f/11, 1/ISO shutter speed for a full moon) serves as an excellent starting point, but photographers must be prepared to adjust by several stops (e.g., +2 to +4 EV) for dimmer phases to properly expose the shadowed terminator and capture subtle surface textures.

The Exposure Science Behind Lunar Photography

The Moon Exposure Calculator determines optimal settings by relating the camera's ISO, aperture, and the moon's luminance (which varies by phase) to calculate the appropriate shutter speed and Exposure Value (EV).

The key formula for Shutter Speed is:

Shutter Speed (s) = (Aperture^2) / (ISO × Scene Luminance)

And for Exposure Value:

Exposure Value (EV) = log₂( (Aperture^2) / (Shutter Speed × ISO) )

Where:

Aperture: The f-number of the lens.
ISO: The sensor's sensitivity.
Scene Luminance: The brightness of the moon for the selected phase (in cd/m²).
log₂: Logarithm base 2.

The calculator uses a pre-calibrated table of luminance values for each moon phase to ensure accurate recommendations.

💡 To understand the precise impact of ISO adjustments on your exposure, our ISO to Stops Calculator can help you quantify changes in light sensitivity.

Photographing a Full Moon at ISO 100, f/8

Let's imagine a photographer wants to capture a full moon using the following settings:

ISO: 100
Aperture: f/8
Moon Phase: Full Moon

Identify Scene Luminance (Full Moon): From internal data, a full moon has a scene luminance of approximately 1500 cd/m².
Calculate Shutter Speed: Shutter Speed = (8^2) / (100 × 1500) = 64 / 150000 = 0.0004266... seconds This translates to approximately 1/2344 seconds.
Calculate Exposure Value (EV): EV = log₂((8^2) / (0.0004266 × 100)) = log₂(64 / 0.04266) = log₂(1499.9...) ≈ 10.55 EV

For a full moon at ISO 100 and f/8, the recommended shutter speed is approximately 1/2344 seconds. This very fast shutter speed is necessary to prevent overexposure of the intensely bright full moon. The resulting Exposure Value of 10.6 EV indicates a bright scene, consistent with capturing the moon's surface details.

💡 For designers working on visual presentation, our Leading Calculator (Typography) can assist in optimizing text layout for readability.

Standardizing Light Measurement in Photography

The principles of light measurement that inform photographic exposure are rooted in established scientific and regulatory standards, even when applied to celestial objects like the moon. The ANSI/ISO standards for film speed (ISO) and digital sensor sensitivity provide a consistent baseline for how cameras respond to light. Light meters, whether external or built into cameras, are calibrated to these standards, typically based on a "middle gray" reflectance of 18%. This standardization ensures that an EV value (Exposure Value) represents a consistent amount of light, regardless of the camera system. Consequently, guidelines like the "Looney 11" rule for moon photography, while empirical, derive their reliability from these underlying measurement standards, allowing photographers worldwide to achieve predictable results by understanding the fundamental relationship between light, aperture, shutter speed, and ISO.

Frequently Asked Questions

What is the 'Looney 11' rule for moon photography?

The 'Looney 11' rule is a popular guideline for exposing the moon, suggesting that for a full moon, you should set your aperture to f/11 and your shutter speed to 1/ISO. For example, at ISO 100, you'd use 1/100s. This rule provides a good starting point for achieving a balanced exposure that captures surface details without overexposing the bright lunar disc. It's a simple, effective technique for lunar photography.

How does the moon phase affect exposure settings?

The moon's phase dramatically affects its apparent brightness, requiring significant adjustments to exposure settings. A full moon is considerably brighter than a crescent moon, as more of its surface is illuminated by the sun and reflected towards Earth. As the moon wanes or waxes, its luminance decreases, necessitating slower shutter speeds or wider apertures (lower f-numbers) to achieve a correct exposure and capture sufficient light.

Why is a fast shutter speed often recommended for the moon?

A fast shutter speed is often recommended for photographing the moon for two primary reasons: to compensate for its extreme brightness and to mitigate the effects of atmospheric turbulence and the moon's apparent motion across the sky. While the moon itself is a slow-moving object, even slight atmospheric distortions or camera shake can blur fine details. A fast shutter speed helps freeze these elements, resulting in sharper, more detailed images of the lunar surface.

What is Scene Luminance in the context of moon photography?

Scene Luminance, measured in candela per square meter (cd/m²), quantifies the brightness of the moon's surface as perceived from Earth for a given phase. A full moon, for instance, has a much higher luminance value than a thin crescent. This metric is crucial because it directly informs the camera's exposure settings. Higher luminance allows for faster shutter speeds or smaller apertures, while lower luminance demands more light-gathering capability from the camera setup.