How to Photograph a Lunar Eclipse: Chasing Exposure as the Light Drops 10 Stops

A lunar eclipse is the most generous event the sky offers: no telescope needed, no dark-sky site required, visible from the middle of a city. Yet most people who try to photograph one get stuck at the same place — the early frames look fine, then the moon starts to darken, and all they’re left with is an orange smudge on a black rectangle.

Here’s why: the difficulty of an eclipse isn’t that the moon is dark, it’s that its light changes mid-event. A full moon is a sunlit rock, as bright as a landscape shot in daylight. An eclipsed moon is lit only by red light refracted through Earth’s atmosphere — roughly 10 stops, a thousandfold, dimmer. The setting that was correct at the start is a thousand times wrong at maximum.

Let’s separate the axes up front: the moon photography guide covers the bright moon — Looney 11, focal length, how big the moon actually lands in your frame. This article covers the few hours when the moon stops being that bright rock.

Why 10 stops? The light source changes

A full moon looks bright to us, but it’s actually a fairly dark grey rock catching direct sunlight. Because that sunlight is direct, the exposure is close to a daylight shot: the Looney 11 rule says f/11 at 1/ISO — 1/100 second at ISO 100. Surprisingly fast.

When the moon enters Earth’s shadow, that source is cut off. Only one kind of illumination remains: sunlight refracted through Earth’s atmosphere and bent into the shadow. Since the atmosphere scatters blue light away, only the red end makes it through — that’s where the copper colour comes from. The same physics reddens sunsets; an eclipsed moon is really every sunrise and sunset on Earth reflected back at once.

That light is about 10-12 stops weaker than direct sunlight. In practice:

Phase	Typical setting (ISO 400, f/8)	vs. full moon
Full moon, before the eclipse	1/400 s	—
Penumbral	1/320 s	barely any change
Shallow partial, 25% covered	1/200 s	~1 stop
Half covered, 50%	1/60 s	~3 stops
Deep partial, over 90%	1/8 s	~5-6 stops
Umbral, red phase	1-2 s	~10-12 stops

Treat these as starting points, not gospel. The colour and brightness of an eclipse differ every time, depending on how much dust and cloud sits in Earth’s atmosphere — eclipses following major volcanic eruptions run visibly darker.

The real difficulty: the partial phase holds two worlds at once

The most beautiful sight of an eclipse — and the hardest moment to photograph — is deep partial: most of the moon has turned red, but a sunlit bright sliver still clings to one edge.

The trouble is that those two regions sit 8-10 stops apart. Expose for the bright sliver and the red goes black; expose for the red and the sliver blows out. This isn’t a lack of skill, it’s the dynamic range wall — the scene doesn’t fit on the sensor.

You have three options:

1. Protect the bright limb. Expose so the highlight isn’t clipped and let the red stay dark. The most honest and most common choice, because a blown highlight holds no data while a shadow holds weak data that can be lifted.
2. Blend exposures. Shoot 3-5 frames back to back (say 1/200, 1/25, 1/3) and merge later. The moon drifts, so the frames need aligning — shoot them quickly and consecutively.
3. Choose to wait. Once coverage passes 95% the bright sliver shrinks and the problem solves itself.

Your meter fails here

Automatic metering nearly always gets an eclipsed moon wrong, for a simple reason: almost the entire frame is black sky. Whatever metering mode you pick, the camera tries to drag all that blackness toward middle grey, overexposes, and turns the moon into a white ball.

Spot metering doesn’t save you either: in deep partial phase the spot lands on either the bright limb or the red region, and those are 8 stops apart, so your result jumps depending on where you aimed.

There’s only one reliable method: manual mode plus the histogram. If the histogram shows a spike jammed against the right wall, the highlights are gone — shorten the exposure. Don’t trust the brightness of your screen: in darkness every frame looks brighter than it is, which is why the most common mistake in night photography is systematic overexposure.

The moon drifts: long exposures don’t work here

In the dark phase, instinct says lengthen the shutter. But the moon doesn’t hold still: Earth’s rotation carries it 15 degrees across the sky every hour. At long focal lengths that turns into blur almost immediately.

The practical ceiling is the 500 rule we already use on the astro side: the longest safe exposure is roughly 500 divided by focal length, in seconds.

• 200 mm gives about 2.5 seconds
• 400 mm gives about 1.2 seconds
• 600 mm gives about 0.8 seconds

So if the red phase needs 2 seconds at ISO 400 and you’re on 400 mm, that exposure smears the moon. The fix isn’t a longer shutter, it’s a higher ISO — going to ISO 1600 and dropping to half a second is the right trade. Noise can be fixed, blur cannot; if you don’t know your own ISO ceiling, the ten-minute test in that article exists for exactly this. Because the light changes fast you might reach for Auto ISO, but keep it off here: the meter is already fooled by all that black sky, and handing it the ISO as well compounds the error.

An equatorial tracker removes this limit, but you don’t need one — this event is comfortably shot untracked.

Gear and setup

Focal length. The moon’s image on the sensor is roughly focal length divided by 110: about 3.6 mm at 400 mm. Against a full frame sensor’s 24 mm short edge, that’s about a seventh of the frame height. For a moon that fills the frame you need 600 mm and up; the effect of focal length is covered in detail in the moon article. An APS-C body is an advantage here — the same lens gives you a tighter frame.

But telephoto isn’t the only way. The eclipsed moon is small, yet the scene is valuable: shooting the red moon low near the horizon with a landscape, a silhouette or a city skyline often makes a better photograph. A frame-filling moon is a technical achievement; a moon in a landscape is a picture.

Tripod. Non-negotiable at long focal lengths. Use a solid tripod plus a shutter delay or remote release; on a DSLR, lock the mirror up.

Focus. Autofocus hunts in the dark. Magnify 10× in live view, focus manually on the edge of the moon, then tape the focus ring. Check it every half hour anyway: focus shifts as the lens cools. Other ways to focus in darkness are in focusing at night.

Format. RAW. The colour of an eclipse is extremely sensitive to white balance and you’ll want to decide later; the RAW versus JPEG difference gets very concrete here. Don’t leave white balance on auto — with most of the frame black, auto white balance jumps between frames and washes the red out. Lock it around 4000-5000 K.

The 28 August 2026 eclipse

This one is a deep partial: 96% of the moon enters Earth’s umbra. That means it looks nearly total — most of the disc in red-copper with a thin bright sliver on one edge.

Global timings (UTC):

Phase	Time (UTC)
Penumbral begins	01.24
Partial begins	02.34
Maximum, 96% covered	04.13
Partial ends	05.52

Where you are decides how much of that you get:

• The Americas get the best view. From New York the partial phase runs from about 22.34 on 27 August to 01.52, with maximum near midnight and the moon high in the sky. Nothing sets, nothing rushes you — this is the full show.
• The UK and western Europe catch it low in the west before dawn: in London the partial phase starts around 03.33 BST and maximum falls near 05.12, with the moon sinking as the sky brightens. Pick a spot with a clear western horizon.
• Eastern Europe, Turkey and the Middle East lose the end of it — the moon sets before maximum. Around 50 minutes of deepening partial phase is all you get, very low in the west.

Six common mistakes

1. Shooting the whole night on one setting. The light moves 10 stops; your settings have to move with it.
2. Judging exposure by the screen. In the dark the screen lies; the histogram doesn’t.
3. Leaving white balance on auto. The red shifts from frame to frame — lock it.
4. Lengthening the shutter in the dark phase. The moon drifts and smears. Raise ISO instead.
5. Waiting through the penumbral phase and losing interest. The real event begins at partial.
6. Betting only on telephoto. Between a frame-filling moon and a red moon above a horizon, the second is usually the better photograph.

If you miss it

Unlike solar eclipses, lunar eclipses are frequent and visible across half the planet — roughly two a year, and everyone on the night side watches the same one at the same time. What you learn on this attempt carries straight over to the next.

Meanwhile, the fundamentals of moon photography can be practised on any full moon. The best way to avoid being caught unprepared on eclipse night is to run the whole setup once on an ordinary one: mount the tripod, focus manually, expose by the histogram. On eclipse night all that’s left is shifting the settings.