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Turning Your Screen Red for Astronomy

on iOS and Android devices

 
 

Astronomers prefer dim red lights to white lights, because dim red light helps preserve night vision. This can make all the difference between seeing or not seeing a very faint target. It is therefore very useful for both you and those around you to be able to quickly make your device screen dim and red.

It is fairly easy to use the Accessibility Shortcut feature of your phone or tablet to add a red color filter to your screen, which you can easily turn on or off as needed. Both iOS and Android have this feature, though triggering it is slightly different for each. Instructions for both are provided below.

iOS - iPhone and iPad

Follow these instructions to set up a red color filter for your screen and then enable a shortcut to turn it on and off. First, we set up the red color filter:
  1. Open Settings and scroll down to open the Accessibility menu.
  2. Select Display & Text Size and scroll down and press Color Filters.
  3. Turn Color Filters on and select Color Tint.
  4. Slide the Hue control all the way to the right to make the color red.
  5. Next, slide the Intensity control most or all of the way to the right until you see a definite effect that darkens the screen with the filter. You can adjust both sliders to your liking, but remember that the goal is to dim the light from the screen and make it redder.
Next, we create a shortcut to make it easier to turn the red filter on and off:
  1. Go back to the main Accessibility menu and scroll down to near the bottom to the General section and open the Accessibility Shortcut menu.
  2. Under Triple-click the Side Button for: check the line for Color Filters.

Now whenever you quickly click the side button on your phone three times (or the home button on devices that have one) it will turn the color filter on or off. Easy.

If you select more than one item in the list for the Accessibility Shortcut menu then a pop-up will appear to let you select which item to turn on or off. You might, for example, also check the box for Dark Mode to let you easily turn that on or off.

 

Android Phones and Tablets

Follow these instructions to set up a red filter and to enable a shortcut to turn it on and off:
  1. Open Settings and scroll down to open the Accessibility menu.
  2. Select Vision enhancements and scroll down and press Color filter.
  3. Turn the color filter on, and turn on the Color filter shortcut.
  4. Select Red for the tint, and slide the Opacity to the right until it has a significant effect.

You can now turn the red filter off or back on by pressing the accessibility icon (Temba, his arms wide) in the lower right corner of your screen.

Also note that in the Color filter menu if you tap on the Color filter shortcut item you can actually set up multiple shortcuts, so you can choose which way works best for you. The options are:

  • Tapping a button in the Quick settings panel
  • Tapping the Accessibility button, with that either appearing in the Navitation bar or floating over other apps
  • Simultaneously pressing the Side button and the Volume up button
  • Holding both the Volume up and Volume down buttons for 3 seconds

You can even enable all of these if you wish.

One advantage of adding the Color filter button to the Quick settings panel is that you can then also easily turn down the overall brightness of the display, since the slider for that is also in the Quick settings panel. Arranging the Quick settings panel to put the Color filter icon near the top of the list makes it even easier.

Last modified: 10 November 2026
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