Lunar Eclipse Exposure Calculator

Enter your camera ISO, lens aperture, and eclipse phase to instantly calculate the correct shutter speed and exposure settings for capturing the lunar eclipse.

Created by Luis GonzalezLast updated: May 9, 2026

How to Use This Calculator

1
Enter your camera's ISO setting
Input the ISO sensitivity of your camera sensor. Higher ISO captures more light but can introduce noise.
2
Specify your lens aperture (f-number)
Provide the f-number (e.g., f/2.8, f/5.6) of your lens. Lower f-numbers indicate a wider aperture, letting in more light.
3
Select the eclipse phase
Choose the current or target phase of the lunar eclipse (Penumbral, Partial, Total—Bright, or Total—Dark/Blood Moon) to apply the correct exposure value (EV).
4
Review ideal shutter speed and exposure settings
The calculator will display the recommended shutter speed, eclipse phase EV, and other exposure guidance for lunar eclipse photography.

Example Calculation

A photographer is planning to shoot a lunar eclipse during its 'Total—Bright' phase, using ISO 800 and an aperture of f/5.6.

ISO

800

Aperture

5.6 f/

Eclipse Phase

Total — Bright (EV 5)

Results

1/102 s

Tips

Bracket Your Exposures

Lunar eclipses cover a wide range of brightness. Take multiple shots with varying shutter speeds (exposure bracketing) to ensure you capture details in both the bright and dim areas, especially during partial and total phases.

Use a Sturdy Tripod and Remote Shutter

Longer shutter speeds required for lunar eclipse photography necessitate a very stable setup. A sturdy tripod and a remote shutter release (or camera's self-timer) will prevent camera shake and ensure sharp images.

Focus Manually on the Moon

Autofocus systems often struggle in low light. Switch to manual focus and use your camera's live view with magnification to achieve critical focus directly on the Moon's surface before the eclipse begins or during brighter phases.

The Lunar Eclipse Exposure Calculator provides precise shutter speed, aperture, and ISO recommendations for every phase of a lunar eclipse, empowering astrophotographers to plan their shoots with confidence. Capturing the subtle dimming of a penumbral eclipse or the dramatic reddish hue of a "blood moon" requires vastly different exposure settings, often spanning 10 or more stops of light. For example, while a full moon might be captured at 1/125s at f/8 and ISO 200, a dark total eclipse might require 1-second exposures at f/2.8 and ISO 3200.

Why Precise Exposure is Essential for Lunar Eclipse Photography

Precise exposure is not merely desirable but essential for successful lunar eclipse photography. The Moon's brightness changes by many orders of magnitude as it enters and exits Earth's shadow, from the subtle dimming of the penumbra to the dramatic darkness of totality. Without carefully adjusting camera settings for each phase, photographers risk either blowing out highlights during brighter moments or underexposing details during the deep total eclipse, resulting in an image that fails to capture the intricate beauty and dynamic range of this celestial event.

The Exposure Calculation for Lunar Eclipses

The calculator uses the fundamental exposure equation, relating shutter speed, aperture, and ISO to a specific Exposure Value (EV) for each eclipse phase.

Determine Exposure Value (EV): EV = (predefined_value_based_on_eclipse_phase)
Calculate Shutter Speed: shutter_speed = (aperture^2) / (ISO × 2^(EV - 3))

This formula allows for precise adjustments across the wide range of light conditions encountered during an eclipse.

💡 Beyond still photography, understanding light and exposure is key for video. Our Video Resolution Bitrate Calculator helps optimize video quality and file size, which is critical for astrophotography time-lapses.

Worked Example: Photographing a Total Lunar Eclipse

Let's plan the exposure for the "Total — Bright" phase of a lunar eclipse using an ISO of 800 and an aperture of f/5.6. The Exposure Value (EV) for this phase is typically 5.

Identify ISO: 800
Identify Aperture: 5.6
Identify Eclipse Phase EV: 5
Calculate Shutter Speed: shutter_speed = (5.6^2) / (800 × 2^(5 - 3)) shutter_speed = 31.36 / (800 × 2^2) shutter_speed = 31.36 / (800 × 4) shutter_speed = 31.36 / 3200 = 0.0098 seconds

Since this is less than 1 second, it's expressed as a fraction: 1 / 0.0098 ≈ 1/102 seconds. So, for the "Total — Bright" phase, the recommended shutter speed is approximately 1/102 seconds.

💡 After capturing your images, you might want to protect them. Our Watermark Opacity Calculator can help you apply subtle branding without obscuring the celestial beauty of your astrophotography.

Photography: Mastering Astrophotography Exposure

Mastering exposure for astrophotography, especially lunar eclipses, requires a blend of technical understanding and practical experience. For the penumbral phase (EV 12), settings might be close to a normal full moon (e.g., 1/125s, f/8, ISO 200). As the eclipse progresses to partial (EV 9), settings shift dramatically (e.g., 1/30s, f/5.6, ISO 400). During total eclipse, particularly a dark "blood moon" (EV 2), exposures can extend to several seconds (e.g., 2s, f/2.8, ISO 1600 or higher). The "Looney 11" rule, a variation of the Sunny 16 rule, suggests f/11 at 1/ISO for a full moon, but this needs significant adjustment for eclipse phases.

Regulatory or Standards Context in Photography Exposure

While there are no direct "regulations" for lunar eclipse photography, the principles of exposure are deeply rooted in established photographic standards and physics. The Exposure Value (EV) system itself, which is central to this calculator, is a logarithmic scale developed to standardize exposure settings across different cameras and lighting conditions. It's an international standard (ISO 2720:1974) that defines how aperture, shutter speed, and ISO combine to produce a given exposure. Professional camera manufacturers and photographic organizations adhere to these standards to ensure consistency and interoperability of equipment. Understanding these foundational principles ensures that photographers can achieve predictable and high-quality results, regardless of their specific gear.

Frequently Asked Questions

What is an Exposure Value (EV) in photography?

Exposure Value (EV) is a system that combines shutter speed and aperture settings into a single number, representing a specific amount of light. Each EV step corresponds to a doubling or halving of the light entering the camera. For lunar eclipses, different phases have vastly different EV values, meaning photographers must adjust their settings dramatically as the eclipse progresses to maintain proper exposure.

Why do lunar eclipses require such varied exposure settings?

Lunar eclipses require varied exposure settings because the Moon's brightness changes dramatically as it passes through Earth's shadow. During the penumbral phase, the dimming is subtle, but as it enters the umbra (partial and total phases), the light can drop by several stops, requiring significantly longer shutter speeds or higher ISO. A 'blood moon' can be 10,000 to 100,000 times dimmer than a full moon, demanding extreme exposure adjustments.

What is the '500 Rule' for astrophotography, and does it apply here?

The '500 Rule' (or NPF Rule for more accuracy) helps determine the maximum shutter speed you can use before stars (or the Moon) start to trail due to Earth's rotation, typically `500 / focal length`. While the Moon moves slower than stars, for sharp images with longer focal lengths (e.g., 500mm), you'd want shutter speeds faster than 1/500s. This calculator's motion risk assessment considers similar principles for lunar photography.