Shooting the Milky Way

Learning goal

On a dark night, at the place and hour you planned, you will be able to build your first Milky Way photo from start to finish. You will know why a wide-angle lens that lets in a lot of light is preferred for the Milky Way, and what is possible with a kit zoom. You will start shooting with starting settings for aperture, time, ISO and white balance, and correct them by looking at the histogram and the magnified screen. Seeing why, with fast lenses, the stars in the corners of the frame look like small birds with their wings spread, you will understand how stopping down by one stop reduces this. You will know how to shoot the foreground that stays jet black in the dark in a separate frame or at twilight and combine them, and that this must be told to the viewer. You will also render the face of a person standing under the Milky Way without losing it, with their skin in its right color.

The question

The stars no longer leave trails, but your friend's Milky Way frame looks dim next to the examples at the club: the dust lanes can't be picked out, the sky is dark and murky, the tree in the foreground a jet-black shape. The kit zoom in their hands doesn't open wider than f/4 at its widest. At the club someone hands them a fourteen-millimeter lens that opens up to f/1.8, and also writes them a list of settings to start with. How do you build your first Milky Way photo?

Context

You just worked on finding, with two rules, the time a star can stay without leaving a trail (Lesson G.5). While setting up the night calendar, you learned in which month and at what hour the bright core will fall in which direction, and when the moon withdraws from the sky (Lesson G.4). In the lens flaws lesson you met the flaws that appear in the corners of the image, corners darkening and color fringes (Lesson 12.7).

The Milky Way is a faint light the eye barely picks out; making it distinct in a photo requires getting as much light as possible to the sensor within a short time. This lesson puts in order the steps you will take when you reach the field on a planned night: which lens, which settings, how to check, how the foreground is shot and how the person in the frame is lit. The settings aren't exact, they are a start; every night and every place is a little different.

Simple explanation

Which lens, which settings?

Two things matter in Milky Way shooting: a wide angle and a lot of light. A wide-angle lens, for example in the 14–24 mm range, shows a large part of the sky and the foreground together; the short focal length also lengthens the time the stars stay points. A lens that lets in a lot of light, f/2.8 and wider, delivers more light to the sensor in the same time. An f/4 kit zoom can also shoot the Milky Way, but at the same time and ISO it gathers one stop less light than f/2.8 and roughly two stops less than f/1.8; this difference means a higher ISO and more noise.

Starting settings are the estimated settings list used for the first frame in the field and then corrected according to the histogram: the aperture at its widest opening or one stop down from it, the time at the value the NPF rule gives, the ISO roughly between 3200 and 6400, focus by hand on a star, the white balance set by hand roughly between 3800 and 4200 Kelvin, and recording in raw. A white balance fixed by hand gives the same color in all the frames; raw recording leaves room to correct both color and exposure later.

How is the frame checked?

After the first frame you look at the histogram: in a night sky frame the peak should often stand a little in from the left side, left of the middle; a histogram stuck entirely to the left edge tells you that dark details are lost. Magnifying the screen and looking at a star, you check the focus and whether the stars are points. Because the screen looks bright in the dark, deciding by the histogram rather than by eye is safer.

Coma is the stars in the corners of the frame, with fast lenses at the widest aperture, looking not like points but like small birds with their wings spread or like drops with tails. This is especially distinct in cheap or old wide-angle lenses. Stopping the aperture down by one stop, for example from f/1.8 to f/2.8, often clearly reduces coma and the darkening in the corners; the lost light is made up with an ISO one stop higher. Which aperture gives the best result on your lens you see by shooting the same frame at two apertures and magnifying the corners.

How are the foreground and a person shot?

A foreground frame is a frame shot separately from the same place, without moving the camera, to show in detail the foreground that stays jet black in the night sky frame, and then combined with the sky frame. This frame can be shot with a longer time and a lower ISO, or before the sky has fully darkened, in the last brightness of twilight. Even if the two frames are shot from the same place on the same night, the combined image isn't the record of a single moment; telling this to the viewer, especially in a competition, is a requirement of honesty.

Showing a person under the Milky Way changes the frame's scale and feeling. The person either stays a dark shape in front of the stars, or their face is lit for a brief moment of the exposure with a small, dimmed light. On light skin this light can blaze in an instant; on dark skin it can merge with the darkness of the sky and be lost. Softening the light with a piece of paper, holding it a little away from the face and adjusting its duration by magnifying the face on the screen keeps the skin in its own tone in front of the sky.

Visual evidence

On the August night they planned, your friend reaches the tree on the plateau before astronomical darkness begins. In the last light of blue hour, from the same framing, they shoot a foreground frame at ISO 400 and four seconds: the tree's bark and the grass are detailed.

Darkness falls. The borrowed lens at its widest opening, at f/1.8, gives the first frame at 3200 ISO and eighteen seconds. The stars in the corners look like small birds. When they stop down to f/2.8 and raise the ISO to 6400, the corners pull together. The peak of the histogram is a little left of the middle; on the magnified screen the stars are points. The galactic core is above the tree, the dust lanes can be picked out.

Selin stands beside the tree, looking at the sky. Just before the exposure ends, your friend holds a dimmed lamp softened with a piece of paper to her face; her dark skin is in its warm brown. At home they combine the sky and foreground frames and, when sharing, write under it: "a combination of two frames of the sky and the foreground shot from the same place on the same night."

Common mistakes

Summary

The first Milky Way photo is built with a wide-angle lens that lets in a lot of light, and with starting settings made up of a wide aperture, the time the NPF rule gives, a high ISO, a white balance fixed by hand and raw recording; the frame is checked with the histogram and the magnified screen, and coma in the corners is reduced by stopping down one stop. The foreground that stays jet black is shot from the same place in a separate foreground frame and combined, and this is told; the person in the frame is either left as a dark shape or has their face opened up with a softened, dimmed light suited to their skin.

Mini assignment

In this assignment you will shoot your first Milky Way frame on the night you planned.

1. Arrive at the place you planned before darkness falls, set up the framing and shoot a foreground frame from the same place with the last crumb of daylight.
2. In the dark shoot a frame with the starting settings and look at the histogram and the magnified screen; shoot at the widest aperture and one stop down and compare the corners.
3. If someone will stand in the frame, photograph them as a dark shape or with a softened, dimmed light; if you combine the sky and foreground frames, write so when sharing.

Check yourself

• Where is the peak of the histogram, and do the sky's details read?
• At which aperture are the stars in the corners points?
• Is the skin of the person in the frame in its own tone in front of the sky?

Glossary

Mini quiz

1. Why is a lens that lets in a lot of light preferred for Milky Way shooting?

• A) Because it is lighter
• B) Because it delivers more light to the sensor in the same time
• C) Because it changes the colors
• D) Because it finds focus by itself

2. In a night sky frame, roughly where should the peak of the histogram be?

• A) Entirely at the left edge
• B) Entirely at the right edge
• C) A little left of the middle
• D) Nowhere

3. How is the bird-like look of the stars in the corners reduced?

• A) By stopping the aperture down by one stop
• B) By lengthening the time
• C) By changing the white balance
• D) By lowering the ISO

4. How is a Milky Way image combined with a separate foreground frame shared?

• A) As a single frame, with nothing said
• B) With the foreground cropped
• C) Never shared
• D) By clearly saying it is a combination

Answers

1. B — A wide opening gathers more light in the short time the stars stay points.
2. C — If the peak stands in from the left edge, the dark details remain without being lost.
3. A — Stopping down one stop clearly reduces the flaws in the corners.
4. D — Because the combined image isn't the record of a single moment, it is told to the viewer.

Summary card

• A wide angle and a lot of light: 14–24 mm, an opening of f/2.8 or wider.
• Starting settings: wide aperture, NPF time, high ISO, white balance by hand, raw recording.
• Look at the histogram; don't trust the screen's brightness.
• If there is coma in the corners, stop down one stop.
• Shoot the foreground frame separately and say it is combined; light the person with a softened, dimmed light suited to their skin.

Bridge to the next lesson

The Milky Way frame is liked at the club. That same night your friend had turned the camera toward the pole star and shot frames one after another for an hour; when they lay these frames on top of each other on the computer, the stars draw nested rings around the pole star. How does the sky turn? The next lesson takes up star trails, a long burst of frames and combining the frames into a trail image.