Taking photos of the Milky Way requires a unique approach. This is why we’ve dedicated an entire article to the best camera settings for Milky Way photography. We use these for 98% of our shots.
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Exposure Settings for Milky Way Photography
Before we get started, I want to make one thing very clear: Always expose for the sky, not the foreground.
When you start adding foreground interest, it can be tempting to compromise on exposure to suit both parts of the photo. Resist the temptation. If you want to get the best image of the Milky Way possible, you’ll want to expose for the sky.
One luxury of focusing at a single point of interest, millions of miles away, is that you don’t need to think about the depth of field. Even if you shoot at f/1.2.
The question isn’t ‘Will everything be in focus?’, it’s ‘Will I have enough light for my exposure’.
After all, we capture photos of the stars during the darkest nights of the month.
For Milky Way photography, I recommend shooting at your widest aperture settings—f/2.8, for example. This will allow the most amount of light into the lens, and allow for a shorter exposure duration.
If you’re taking a photo where you include some foreground interest, such as the tree in the image below, then f/2.8 is the magic spot. It’s wide enough to allow plenty of light into the lens while providing enough depth of field to get the foreground in relative focus.
But how long is the longest possible? We can set almost limitless exposures on our cameras. But there’s a very specific limit to how long you can expose for photos of the stars. Set too long of a time, and the stars will start to move in the sky, and those sharp dots of detail will look like soft smudges.
Fortunately, there’s a very easy way to work this out with a quick calculation involving your focal length, called:
The 500 Rule
The 500 Rule calculates the longest exposure time possible for Milky Way photography before the movement of stars starts to show.
It’s easy to use: divide 500 by the effective focal length of your lens.
For example, 500 divided by 14mm would be 35.7; this means 35.7 seconds is your maximum advised exposure length.
For that same calculation again, this time for a 24mm lens, the result is 20 seconds.
The reason for this is because when your perspective is tighter, the movement of stars is relatively faster. The idea is the same as in the reciprocal rule, but this time your camera is steady, and your subject moves.
So the wider your lens is, the more time you have to expose for the stars.
Keep in mind that the rule calculates with your effective (or equivalent) focal length. If you’re using a crop sensor camera, then your smaller sensor crops into the scene. This gives you a tighter field of view.
So if you’re shooting with a Canon crop sensor, you would want to divide that final number by 1.6. If you’re using another model, you would divide it by 1.5.
For example, if you had a 14mm f/2.8 lens, but you put it on a Canon crop sensor body (like a Digital Rebel or a 70D), you would divide 35.7 seconds by 1.6. This gives a 22.3 second exposure time. If you were shooting on a Nikon crop sensor (like a D5300), you would divide 35.7 seconds by 1.5 for a 23.8 second exposure time.
All you have to remember is that you take 500, divide it by your focal length. And if you’re on a crop sensor camera, divide that number again by the magnification factor.
Limitation of the 500 RulePlease note that the 500 Rule is not a “rule”, it’s rather a guideline. If you have a modern, high-megapixel camera, it doesn’t really work. Higher resolution means smaller pixels, which mean more detail. Motion blur will appear sooner. Experiment with your own setup and check if there’s noticeable motion blur showing up when calculating with 500. If there is, try it with 400 or even 300, until it disappears. You’ll get faster shutter speeds, so you’ll likely need to raise your ISO a bit to compensate. This will result in more noise – but if you have to choose between noise and blur, go with noise. It’s easier to filter out noise during editing.
Unlike aperture and shutter speed, there are no rules on what you can set the ISO to. It’s important to remember that the higher the ISO, the noisier the image will be.
Using a modern full-frame camera, you will quite easily get away with setting your ISO up to 12800. Modern crop sensors will produce fairly clean night sky images at 6400 or lower.
Any higher than that will show too much degradation in the image quality. At that point, you’re probably better off pushing it in post-production.
How Do you Focus the Milky Way in Photography?
Focusing on the Milky Way is super simple.
All you need to do is to set your focus at infinity. This looks like the figure-eight symbol in the image below.
On Canon cameras, you want to line up the little sideways L with the line to focus on infinity. On other cameras, you’ll want to align the infinity symbol with the line. Always check to see how it works on your lens.
Once you’ve set your focus to infinity, turn your focus mode to manual. This way, your camera won’t try to refocus in the dark when you go to take a photo. It will not do a good job!
Remember also to check your focus every time you recompose your shots. It’s very easy to knock the focus ring and send your photo into a blur. If you’re not sure if your marking is accurately placed, check it in daylight. Focus to infinity using live view, and see if the signs line up.
If you don’t have a focus scale on your lens, use manual focus with the help of live view magnification. Be warned, it’s not an easy task in the dark!.
In-Camera Long Exposure Noise Reduction
A useful but time-consuming function of digital cameras is In-Camera Long Exposure Noise Reduction.
The camera does this by first taking a regular 30-second exposure. Once that’s captured, the camera will close the shutter and capture another 30-second ‘blank’ exposure.
The camera will then compare the blank exposure to the original photo. It does this to identify the digital noise, and then remove it from the original photo.
And it does a pretty good job!
But as with everything to do with exposure, there is one major downside: time.
This process is very time consuming and will drain your battery life, so it’s not perfect. If you’re taking many photos for a panorama, it won’t be quick enough to capture photos without the stars moving too much to stitch together later.
Conclusion: Our Go-To Settings
So, what settings do you use to shoot the Milky Way? These are the settings we use for 98% of our Milky Way photography.
These are specific to our gear. Once you’ve worked out the settings for your equipment, you’ll find that you can use the same settings for most of your shots.
Here they are:
- Focal Length: 14mm (on a full-frame sensor)
- Aperture: f/2.8
- Shutter Speed: 30 seconds
- ISO: 3200
- Focus: Manually set to infinity
- In-Camera Long Exposure Noise Reduction: Off
Before you go, check out this video on top camera settings for Milky Way photography!
To perfect your skills, try our Milky Way Mastery course today!