Smartphone Astrophotography - How To Capture The Night Sky With Your Phone

Guide to Smartphone Astrophotography so you can photograph the night sky with your mobile phone camera connected to a telescope.

By Tim TrottAstrophotography • November 13, 2019
832 words, estimated reading time 3 minutes.
Smartphone Astrophotography - How To Capture The Night Sky With Your Phone

Astrophotography can be pricey as part of your spare time activities; however, your mobile phone can also be as good as a pricey DSLR or CCD camera.

Although many smartphone cameras now offer many sensor pixels, low light sensitivity and low noise are also needed for low-light astrophotography. It's these two factors that smartphone cameras haven't developed to the same level as DSLR cameras. Bright objects like sunsets, sunrises, brighter planets, and the Moon are different and present very good targets for smartphone astrophotography.

Creating a photograph of any respectable scale and high quality to show detail on the Moon isn't easy with a smartphone camera. This is because the lens has no zoom or only a limited zoom capability. We can, however, use a technique called afocal coupling, which is when we point the camera down the eyepiece of a telescope or even binoculars.

How To Capture The Night Sky With Your Mobile Phone

The basic concept is simple. You point the telescope at the Moon, focus it and then point the camera down the eyepiece. When the Moon's image is nicely framed on the phone's display, press the shutter button, and that's done.

Simply holding the smartphone camera to the eyepiece
Smartphone Astrophotography

Of course, in practice, things aren't so simple. However, the basic principle continues to be sound.

First, you'll want to set up your telescope or spotting scope with an eyepiece, or you can use binoculars. Choose a low to medium-power eyepiece; a 25mm is sensible. If your telescope is equatorially mounted, a motor drive and polar alignment are smart assets because they will keep the telescope pointing directly at the Moon, providing you with one less thing to worry about. Don't worry if you don't have a driven mount because you can still get a shot. Without a drive to keep things centred, use a low-power eyepiece. This will restrict the apparent speed of the Moon as it moves across the frame.

Point the telescope at the Moon and focus through the eyepiece as best you can. If you wear glasses, it's a good suggestion to focus them so that the view the phone camera gets is as normally focused as possible.

Before you get started, take a second to spot where your digital camera lens is situated in your phone. This would possibly sound a little obvious. However, it's surprising how easy it is to mistake the lens for the small flash window. Many more recent phones have a couple of lenses, complicating things further. If you have more than one lens, aim to use the medium one, the "normal" or 1x lens. For now, avoid wide-angle and telephoto lenses.

Cheap smartphone holders can be found for as little as £5
Cheap smartphone holders can be found for as little as £5

Open the digital camera app and with the Moon centred through the eyepiece, hold the phone up to the eyepiece so that it's pointing directly down the barrel. This is the important bit and the hardest part to achieve. If your phone isn't pointing directly down the eyepiece, you will not see anything on the phone's screen, even if the angle is off by a few degrees.

You'll want to hold the camera somewhat close to the eyepiece first, but once you have the image in the frame, experiment with different distances until you get a comfortable view. Try not to touch the eyepiece itself. This may cause the telescope to move, which means you might be trying to line up with an empty view.

Once you've got the Moon on the display, double-check the orientation of your phone so that the camera lens is looking directly down the eyepiece. This makes all the difference to the final shot because if you get it right, the light coming out of the eyepiece would be the brightest and evenly spread as it enters the phone's camera lens. You can get a gentle brightness degradation across the field of view if you're slightly tilted.

When you are all lined up, the only thing left to do is take the shot. Here, one last hurdle appears to thwart you - as you press the shutter button, you'll likely move the phone in the procedure. The best way around this is to be gentle. You can use the timer function or, if your phone supports it, use a hands-free headset to control the shutter with the volume button.

Most mobile phone cameras don't offer much control for exposure. However, the Moon should be bright enough to trigger auto-exposure functions, so the shot comes out appropriately.

Smartphone Astrophotography Brackets and Mounts

Find yourself frequently taking pictures in this manner. You may be interested in purchasing a few low-cost devices that will help you attach the smartphone to a telescope. Once you have centred the lens on the eyepiece, these little brackets will hold the phone in place.

About the Author

Tim Trott is an avid stargazer and astrophotographer whose passion for the cosmos fuels a lifelong journey of exploration and wonder. Through Perfect Astronomy, he shares the beauty of the night sky and the art of capturing it, blending science and creativity to inspire curious minds and aspiring astrophotographers alike. Join him as he turns every starry night into a story waiting to be told.

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