Have you ever tried taking iPhone photos of stars or the moon, only to be disappointed by the results? With no optical zoom, it seems impossible to use the iPhone for true night sky photography. However, with a few simple solutions you’d be surprised how much fun you can have shooting the night sky with your phone! In this tutorial you’ll discover some handy exposure tips for improving your iPhone photos of the night sky, as well as how to create wonderful star trail photos.
Shoot The Moon
The biggest problem with shooting the moon on an iPhone is with image exposure. Because the moon is so small in the field of view, the camera won’t adjust the exposure settings to appropriately expose for the moon.
Most of the frame will be taken up by the dark sky surrounding the moon, and the result of this is that your camera will expose the scene for the dark sky. Because the moon is so bright relative to the night sky, what this means in practical terms is that the moon will be over-exposed.
Even if you tap on the moon to try to re-adjust the exposure point, it’s likely that the camera still won’t expose properly for the moon as it’s too small in the frame and there’s still too much black space around it.
To work around this, you need to set the exposure manually. Luckily for us, this is very easy to do in the iPhone’s native camera app. Once you’ve tapped on the screen to set focus, simply swipe down to reduce the exposure. You’ll see the sun icon on the exposure slider and the image will begin to appear darker as you swipe.
If you’re familiar with ISO and shutter speed settings, you may prefer to use a third-party camera app which will allow you to lock the focus and exposure points separately, as well as selecting an appropriate ISO and shutter speed.
The aim is to use a low ISO to avoid getting a grainy picture, and to use a relatively fast shutter speed to avoid camera shake. The native camera app won’t show you the ISO and shutter speed numbers, so it’s all guesswork.
So you might find certain third-party apps that show ISO and shutter speed settings more useful when taking photos of the moon. Here’s a basic walkthrough:
2. Hold your iPhone up to a bright light and read the on-screen exposure settings. Lock the exposure when the settings are around ISO 50 and shutter speed between 1/250 and 1/750 depending on the phase of the moon (faster speed for brighter moon).
3. With your exposure still locked, go outside and focus on the moon. A tripod helps, but might not be necessary especially at faster shutter speeds and if you have a steady hand.
4. Lower your expectations. The full moon will only be about 50 pixels across in your photo. But, if it’s properly exposed, you should see differences in dark and light patches on the face of the moon.
Photograph Star Trails
As the Earth turns, the stars appear to move across the sky. If you take a long exposure photo of the sky, the stars will appear to make light trails or circles. The North Star is the only star that appears to stay in the same place because it’s very close to the north celestial pole above the Earth.
Long-exposure photography facing the North Star reveals circular pathways as the stars (relative to us) move around the pole. Did you know that you can use your iPhone to make star trail photos?
For star trails, I use the NightCap app because of its ability to take continuous back to back shots at timer-regulated intervals.
The app also lets you choose between JPEG, HQ JPEG and TIFF outputs, however the TIFF isn’t available for the continuous burst mode.
Manual exposure lets you select from 1/20 to 1 second shutter speed, or just do what I did and lock the exposure when you find the right combination of shutter and ISO. To give the stars enough time to travel a tiny bit between shots, set the interval to around 15-20 seconds.
You’ll definitely want to use a tripod or prop your phone up on a railing to keep it steady. I usually keep mine plugged in so it doesn’t drain the battery too quickly (which can happen in about 10 minutes in the winter). Take back to back photos for at least 20 minutes to see some decent trails – the longer the better!
Now that you have a ton of grainy green and black photos filling up your iPhone, dump them all onto your computer and stack them using the free software StarStaX.
You can also stack them by hand in Photoshop using layers and the Lighten blend mode. You basically want to take the brightest pixels from each frame and layer them into the final star trail photo.
Star trail purists might give you a hard time for stacking (rather than leaving the shutter open the entire time for seamless trails on a single frame), but there just isn’t a way to manually keep the shutter open for this long on an iPhone.
In the photo below you can see the final product of this process.
How To Take Sharp iPhone Night Photos
In addition to this article, I created a free video revealing how you too can take perfectly sharp iPhone night photos.