Dylan O’Donnell, deography.com, CC0, via Wikimedia Commons
The Sony A7III is known for its reliability and versatility. It’s a full-frame camera with a wide range of ISO’s. It’s quite expensive, but it makes up for the price with excellent performance. It’s no secret that the Sony A7III can take some incredible daytime photographs, but as it turns out, it can take some stunning night sky photographs as well. I’ve created this ten-step guide to show you how.
Follow these steps to photograph the night sky with a Sony A7III.
1. Get the right equipment
Alright, you have your Sony A7III, but that’s not the only thing you’ll need for astrophotography. You need a powerful lens with a fast aperture and a high-quality tripod.
First of all, you’ll need a lens. The Sony A7III comes with a 28-70mm f/3.5-5.6 OSS lens, this will work for astrophotography, but if you want the best photos possible. We recommend you buy a new lens with a faster aperture. Aperture is measured as an f/number. (A lower f/number is a faster aperture) Anything under f/3.5 is excellent for astrophotography. The reason you want a fast aperture is that this allows more light to enter your lens. You want to absorb the most light possible since the night is very dark. A slower aperture will cause your photo to be underexposed or noisy – if you compensate with extra ISO.
You also want your new lens to be wide-angle. A wide-angle lens allows you to increase shutter speed without needing to worry as much about star trails as much. Sometimes, people photograph star trails on purpose, but in this case, those are something we don’t want. This is important because a higher shutter speed takes in a greater amount of light. Finally, you want a lens with a manual focus indicator. To focus on the stars, you must focus on infinity. This is easier to do using a manual focus indicator, but it’s not impossible to focus on infinity without one.
Now that you have a lens, you need a tripod. Night sky photographs require long shutter speeds and your camera must be perfectly still the entire time your shutter is open or your photo will blur. It’s almost impossible to hold your camera completely still for 30 seconds straight no matter how steady you think your hands are. That’s where a tripod comes in. Tripods hold your camera perfectly still and are easy to aim where you want your camera to go. You can find a tripod on Amazon for around $50-100. Don’t go cheap – tripods are crucial to astrophotography.
If you can’t get a tripod, you can place your camera on a solid object, the ground, or a chair but good luck pointing your camera where you want it to.
2. Find a place with low light pollution
One of the most important factors in photographing the night sky or simply observing it is light pollution. Light pollution is when man-made lights outshine the stars and galaxies in the night sky. Our galaxy, the milky way is invisible to almost 80% of Americans. If you’re currently thinking What!? You can see the milky way? then you have proved my point. In cities and towns, most stars are invisible to the naked eye and to your camera as well. It’s best to drive out to a rural area or a national park as these places are usually darker. Places with low light pollution are called dark sites and you can see thousands of more stars and the milky way in one of these spots. Just to emphasize how important this is, it’s better to take photos with an entry-level camera in a dark site than with a professional camera in a big city.
Two great websites to find dark sites are https://darksitefinder.com and https://lightpollutionmap.com. Light pollution map is more detailed but Dark site finder has a more accurate representation of how far light pollution will travel, so I like it better, but they are both good websites.
The colors on the map represent light pollution and the pins on the map are user-submitted dark sites. You can zoom in on the website and type in your location so be sure to check it out instead of just using this image.
There is a key to how light pollution is represented. The colors on the left mean low light pollution and the colors on the right mean high light pollution. Be careful though, it’s very easy to mix up the grey on the bright side of the scale, with the grey on the dark side of the scale. One of them means lots of light pollution while the other means very little.
This scale is useful but it doesn’t really provide much information on what to expect so I made my own scale.
|Light Pollution||Comparison||What to expect|
|White||Urban||Almost no stars and lots of skyglow, glare, and light pollution.|
|Red||Urban/Suburban||A small number of stars with some skyglow and glare from street lights.|
|Orange||Suburban||Some stars but no milky way galaxy.|
|Yellow||Suburban/Rural||Some stars but no milky way galaxy.|
|Green||Rural||A good amount of stars and a faint milky way galaxy.|
|Blue||Dark/Rural||An excellent amount of stars and a good milky way galaxy.|
|Black||Dark||An excellent amount of stars and an excellent milky way galaxy.|
You should also remember, a higher elevation is better for astrophotography. Mountains can block light pollution from nearby cities and towns. However, they also block the sky. Try to pick a place that isn’t too humid as well since this can amplify light pollution. You should also take climate into account so you don’t pick a place that’s too cold or a place that’s cloudy often.
3. Pick a date and a time
Now that you’ve picked the location, you need to pick a date and time as well. There are quite a few things you need to consider that you might not have thought of. Consider the weather, temperature, phase of the moon, season, meteor showers, and other celestial events.
First, you need to consider the weather and the temperature. You can check that at https://weather.com make sure you’re checking the weather for the location that you choose, not the weather for where you currently live. Make sure there are clear skies and preferably that it’s sunny the entire day and the day after, this is because clouds can roll in earlier than expected if the wind changes. So if it’s scheduled to be cloudy the day after the day you chose, just remember the clouds might come early. You should also check the temperature so you can dress accordingly, the night can be very cold. Remember to check the weather every day, since weather forecasts can change minute by minute. Don’t be disappointed if it’s too cloudy the day you chose to go, just go again another day.
Next, consider the phase of the moon. The moon can actually cause light pollution and outshine other stars. So make sure you pick a day where there is a new moon or a crescent moon. A full moon or gibbous can completely ruin a photo even if it’s not in the frame. You can check the phase of the moon here.
You should also remember the season, this is important because certain constellations are only visible during certain seasons. But most importantly, the milky way is its brightest in certain seasons. In the northern hemisphere, the core of the milky way is visible during the summer, in the southern hemisphere, it’s visible during the winter. You should definitely have the milky way in your photo, but if you can’t, I recommend photographing the Orion nebula – which is usually visible when the core of the milky way isn’t.
Finally, you need to consider meteor showers and other celestial events. There is a common misconception that meteor showers are once-in-a-lifetime events with hundreds of meteors every minute, but this is not true. Meteor showers happen multiple times a year and the best of them have around 100 meteors an hour. What your thinking of is a meteor storm – they happen every 33 years. You’re not guaranteed to capture a meteor during a meteor shower – it’s very hard to do. But it definitely increases your chances, so you should plan to visit your dark site during a meteor shower. Here is a list from the American Meteor Society.
4. Switch to manual mode
When the time comes visit your dark site. The Sony A7III has five main modes, automatic mode, aperture priority mode, shutter priority mode, programmed mode, and manual mode. We’re only going to be using manual mode and aperture priority mode a bit later. Automatic mode sets the exposure for you. Aperture priority mode lets you set the aperture while everything else is set for you. Shutter priority mode is the same but you set the shutter speed. Programmed mode is automatic but you can set some non-exposure-related settings. Finally, manual mode allows you to set everything yourself, this is what we want since the other modes on the Sony A7III will adjust exposure to photograph the landscape, not the stars.
To enter manual mode, turn the mode dial on the top of your camera until the line points to the letter M. Now we’re going to set our aperture, shutter speed, and ISO.
5. Set your aperture
The night is incredibly dark so you want to set your aperture to its fastest possible setting in order to take in more light. However, on some lenses, the maximum aperture speed decreases as you zoom in. For instance, the kit lens that comes with the Sony A7III is the Sony 28-70mm F3.5-5.6. It has a maximum aperture of f/3.5 when completely zoomed out and a maximum aperture of f/5.6 when completely zoomed in. For this reason, we recommend you zoom out to the max. Zooming in your lens can also cause star trails But if you feel that zooming is a must, here is a list of apertures and whether or not they are acceptable for astrophotography.
F/4 is the absolute slowest aperture (highest f/number) I would consider for photographing the night sky. Anything slower than that will underexpose your photo. However, the fastest aperture your lens is capable of is recommended, only use a slower option if you want to zoom in.
6. Change your shutter speed
Shutter speed is another thing that allows more light into your camera. It’s the amount of time that your shutter is open for. Technically, you can open it for as long as you want, but there is a reason that you don’t. Because of the rotation of the earth, the stars seem to move. This means if you kept your shutter open for too long, the stars would start to look like lines instead of dots, as your camera would be capturing the movement of the stars. This effect is called star trails. Some people use a star tracker which rotates your camera as the earth rotates so you can open your shutter as long as you want. But those are expensive and come with their own problems as well.
So you want the most shutter speed possible without any star trails, we can accomplish this by using the 500 rule. The 500 rule is when you divide 500 by the focal length of your camera and use this as your shutter speed. If the focal length of your lens is 28mm then the maximum shutter speed you should use is approximately 18 seconds since 500/28 = 17.857. The Sony A7III is a full-frame camera so this works, for a crop sensor camera there are some extra steps required. I made a table so you don’t have to do the math.
|Focal Length||Shutter speed|
This is yet another reason you should zoom out to the maximum amount. The more zoomed out you are the more aperture and shutter speed you can use.
7. Adjust your ISO
ISO is essentially how sensitive your camera is to light. And you probably predicted it – you want a lot of ISO, but there’s some sort of catch. More ISO means a brighter photo but high ISO can amplify glare and especially sky glow. Skyglow is when light pollution lights up the sky. Because of this, you should never use ISO based on the amount of light pollution present. In highly light-polluted cities and towns I always use the minimum amount of 100. In low-light pollution areas, I use up to 6400. You shouldn’t go above 6400 ever though since ISO also causes noise and grain in your photo. I made a table on how much ISO you should use depending on light pollution – yes I really love tables.
|Light Pollution Level (from Dark Site Finder)||Recommended amount of ISO|
So the perfect settings for astrophotography are your lenses’ maximum aperture, shutter speed using the 500 rule, and ISO using this chart. You also want to be as zoomed out as possible.
8. Focus to infinity
Now you must focus on infinity. Focusing to infinity is when you set your lens to focus distance to its maximum amount. This is how you focus on the night sky or the moon. If you bought another lens you might have an infinity focus indicator. If so, you can manually focus on infinity by adjusting your manual focus ring until it perfectly lines up with the infinity symbol on your lens. However, if you are using the kit lens that came with the Sony A7iii, this is not an option. To focus on infinity you can focus on the horizon during the day, focus on the moon – manually or automatically, or focus on a distant object. This won’t focus to infinity perfectly, but it should be close enough to take some sharp photos of the night sky.
9. Take the photo
Now that you’ve got everything ready and you’ve adjusted your exposure settings. It’s time to take the photo. However, each time you take a photo you have to wait upwards of 10 seconds each time. This is very time-consuming so usually, I take some test photos first. I take my test photos in aperture priority mode with the fastest aperture possible the rest of the settings aren’t the best since there automatically set but they allow you to see the landscape in the background. Try to get some mountains or trees in the background since a photo with only the night sky is kind of bland. You should also try to aim at the milky way or a constellation like Orion. Once you’re happy with the test photo, switch back to manual mode and take the final photo. Make sure your settings are back where they were before. While the photo is being taken, look in the sky for airplanes, satellites, and shooting stars since they are easy to mix up. You don’t want to have a meteor in your photo and not be sure whether or not it was a meteor. You should also take the photo again if you see an airplane since these are kind of ugly. Your photo may look brighter than it really is since your eyes have adjusted for the night, so just keep that in mind.
10. Post process the photo
It’s not over yet! Now that you’ve gone back home and loaded your photos onto your computer, it’s time to post-process your photos. Post-processing is enhancing your photos with software like Adobe Photoshop or Adobe Lightroom. This isn’t considered cheating in the photography community and most milky way photos you see online have been post-processed. You also have to remember, your not adding things to your photo, your only enhancing what was already there. Here are some advanced post-processing techniques you can do with Adobe Lightroom.
However, Adobe Lightroom is not a free software, it costs about $10 a month. If you can’t afford this, or if these advanced techniques are too difficult. You can use this simpler post-processing technique with the free mobile version of Adobe Lightroom for iOS and Android.
Let’s say this is the photo that you’ve taken.
The first thing you want to do is adjust the exposure slider. If your photo is too dark, increase it, if your photo too bright, decrease it. The exposure is honestly fine on this photo already so I won’t be changing it.
Next, you want to add contrast and highlights to your photo. Use a good amount but not too much or it starts to look weird. This will make the stars brighter and the sky darker to look more realistic.
Next, increase clarity to the maximum amount possible. This makes the stars pop and the milky way clearer.
Then, you want to lower the temperature slider. This will bring out the cool colors in your photo. If you slide it to the right, it will increase the warm colors. This is personal preference, but most people like including me like a cooler milky way photo, rather than a warm one.
Finally, you should increase the saturation. This will really enhance the colors of your photo. Don’t add too much or it will look fake, don’t add too little or your photo will be bland. Remember, we’re not adding colors, we’re just revealing them.
Here is a before and after picture.
Notice the green on the corner of both photos. This is an optical phenomenon called airglow (not to be confused with skyglow) that causes the night sky to glow green in dark sites. You might not have noticed this had you not post-processed.