Photography Calculators
Lunar Eclipse Exposure Calculator
https://www.photosizing.com/calculators/lunar-eclipse-exposure/
Estimate only — not a light meter, a shooting prescription or a studio plot. Confirm on a test shot.
Lunar Eclipse Exposure Calculator
A full moon is roughly Looney 11: f/11 at 1/ISO. Totality is another world — the umbra can be 8 to 12 stops down depending on how dusty the atmosphere is (Danjon scale). This starts from f/11 at 1/ISO, scales to your aperture, then adds phase stops. Histogram a test shot; totality changes by the minute.
Inputs
Results
- Shutter
- 0.0006s
- Shutter reciprocal
- 1,543.4
125 means 1/125 s. Under 1, read the seconds output instead.
Recommended gear
Fast astro lens
A 300–600 mm or a short fast prime with a crop is the usual moon kit. Totality wants the extra speed.
Typical range: $400–$1,500
Carbon fibre tripod
Totality shutters stretch to seconds. A 400 mm on a wobbly tripod is a smear, not an eclipse photo.
Typical range: $80–$400
10-stop ND filter
Not for totality — for the bright partial if you want a long-exposure moon disk. Pull it before umbra.
Typical range: $40–$150
Calculation method
Start from Looney 11: f/11 at 1/ISO. Scale shutter by the square of (your f-number over 11) so a faster lens shortens the time. Then multiply by 2 to the phase-stop count: none for penumbral, 3 for a typical partial, 8 for a bright copper totality, 12 for a dark Danjon umbra. Reciprocal is 1/time for shutter dials.
Exact formula
t = (1/ISO) × (N/11)² × 2^phaseStops. Reciprocal = 1/t. Phase stops: 0 penumbral, 3 partial, 8 bright total, 12 dark Danjon. Limits: Looney 11 is a full-moon starting point, not photometry; Danjon is visual; umbra brightness varies; Earthshine, clouds and tracking omitted.
White balance
Totality is red-brown. Daylight WB keeps that. Auto WB will try to make the umbra grey. Shoot RAW.
Highlight on the limb
During partial, the bright crescent will blow if you expose for the umbra. Expose for the bright part until totality, then jump to the total setting.
Frequently asked questions
Why Looney 11, not Sunny 16?
A full moon is about one stop brighter than sunny 16, so the usual starting point is f/11 at 1/ISO. Phase stops are extra time on top of that moon, not on top of daylight. If your full-moon test shots want Sunny 16, add a stop of time or ISO.
Partial phase keeps changing.
Yes. The 3-stop partial is a middle-of-the-bite guess. Bracket as the umbra grows. Do not set one shutter for the whole eclipse.
Can I track?
A tracker lets you use the longer totality times without trailing. Untracked, also check the 500 rule on your focal length so the moon does not smear.
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