Milky Way Camera Settings: ISO, Aperture and Shutter Speed to Start With

Basic settings for Milky Way photography

The Milky Way is only just visible to the naked eye, so you capture it by opening the aperture wide, exposing for several seconds to a dozen or so, and raising the ISO. The basic idea is to keep the shutter open as long as the stars stay as points, then make up the remaining brightness with ISO.

Decide the shutter speed first and then the ISO, and you will not get lost. Wide open is the default aperture, but if your lens turns stars in the corners into bird-wing shapes wide open, stopping down a little will clean them up.

Shutter speed by lens

These are the shutter speeds that keep stars as points when aiming at the Milky Way core (Sagittarius, declination −29°). The camera setting column is the nearest 1/3-stop value that does not exceed the calculated time.

The NPF rule is a strict guide that keeps stars almost round even at 100%. If you are only posting to social media, you can stretch to the simplified NPF rule (about 22 seconds at 14 mm f/2.8) and the stars will still look like points. For which standard to use, see the difference between the NPF rule and the 500 rule.

ISO by sky darkness

With the same shutter speed and aperture, the darker the sky, the higher the ISO you need. The table below takes f/2.8 for 20 seconds at ISO 3200 under a very dark sky as the baseline, and converts the differences in aperture and time into brightness.

An f/1.8 lens is about 1 1/3 stops brighter than f/2.8, so you can shorten the exposure and still keep the ISO at almost half. If you want pinpoint stars with less noise, a fast prime lens makes the biggest difference. Treat the values in the table as a starting point: take one shot and adjust until the histogram peak sits a little away from the left edge (left of centre).

Example settings for APS-C and Micro Four Thirds

Cameras with smaller sensors show a narrower view at the same focal length and have finer pixels, so the time before stars trail is shorter. Choosing a fast wide-angle lens is the key.

All of these assume you are aiming at the Milky Way core. High-ISO noise is more visible on smaller sensors, so either keep the ISO down with a fast f/1.4 to f/1.8 lens, or take several frames of the same composition and stack them (averaging reduces noise).

Camera settings to check before you go

• Turn off image stabilisation (on a tripod it can actually introduce tiny movements)
• Turn off long-exposure noise reduction if you plan to take many frames. When it is on, the camera spends as long processing as it did exposing
• Fire the shutter with a 2- or 10-second self-timer or a remote to avoid shake from pressing the button
• Lower the screen brightness. A bright screen makes images look brighter than they are and leads to underexposure
• Switch from autofocus to manual focus and tape the focus ring so it cannot move
• Bring a spare battery. Batteries run down faster in the cold
• Prevent dew on the lens with a lens heater or hand warmer. Even in summer, lenses fog up easily at night in the highlands or by the sea

If your camera records GPS coordinates, that can be a problem when you would rather not reveal where you shot. For how to check before posting to social media, see how to remove location data from photos.

When and where the Milky Way is easiest to see

The brightest part of the Milky Way (the direction of the galactic core) lies around Sagittarius. From mid-northern latitudes such as Japan, Europe and most of North America, it appears in the southern sky in summer. June to August is easiest, visible from early in the night; in spring (March to May) aim for the hours before dawn, and in September for the early evening after sunset. The Milky Way is there in winter too, but you see a fainter part away from the core. In the southern hemisphere the core rides higher in the sky, and the best season runs roughly from April to September.

• Pick a few days either side of the new moon. Moonlight brightens the sky and washes out the Milky Way
• Choose a place out of reach of city lights. In the direction of a city, the sky is bright from the horizon up
• Choose a day with dry, clear air. Humidity, haze or dust lower the contrast
• Wait 15 to 30 minutes after you arrive without using a light so your eyes adjust to the dark

1. 1

   Compose and lock the camera on the tripod

   Scout the location in daylight and decide how the foreground and the Milky Way will line up, so you are not rushing on the night.

2. 2

   Focus on a star

   In live view, magnify a bright star as far as possible and stop the focus ring where it looks smallest and sharpest. If you are including a foreground, use the hyperfocal distance from focusing for nightscape photography.

3. 3

   Set the time and ISO and take a test shot

   Take one shot with the time and ISO from the Astrophotography Calculator, then zoom in to check the star shapes and use the histogram to check the brightness.

4. 4

   Shoot a few variations

   Also take frames one stop up and down in ISO and with a slightly longer exposure, so you can pick the best one when you get home.

FAQ

What ISO should I use for the Milky Way?

Under a very dark sky, start with ISO 6400 at f/2.8 for 10 seconds, ISO 3200 at f/2.8 for 20 seconds, or around ISO 3200 at f/1.8 for 8 seconds. In the suburbs halve those values, and with moonlight go down to about a quarter.

What shutter speed should I use for the Milky Way?

For pinpoint stars on a 24 MP full-frame camera, use about 10 seconds at 14 mm f/2.8, about 6 seconds at 20 mm and about 6 seconds at 24 mm (NPF rule, aiming at the galactic core). If you are only viewing on social media, stars still look like points at around 20 seconds at 14 mm.

Can I photograph the Milky Way with a kit lens (18-55 mm f/3.5-5.6)?

Yes, but because it is a slow lens, conditions are tougher. On a 24 MP APS-C camera at 18 mm f/3.5 aimed at the Milky Way, the NPF rule gives about 7.2 seconds (6 seconds on the camera), and you need ISO 12800 to 16000 under a dark sky. To shoot a stop brighter, consider a wide-angle prime of f/2.8 or faster.

Why does the Milky Way not show up, or look faint?

Usually the sky is too bright or the shot is underexposed. Check whether the moon is up, whether you are facing city lights, whether the galactic core has risen yet, and whether your ISO is too low. A bright screen can make a too-dark image look fine, so confirm with the histogram.

Can I leave white balance on auto?

If you shoot RAW you can change it later, but it is best to fix it at around 3800 to 4200 K when shooting. On auto, the colour changes from frame to frame, which causes uneven colour when you stack several frames or make a time-lapse.