On Tuesday morning I received an excited message from a friend and talented astrophotographer about a brand-new accessibility feature in Apple's new iOS 10 software.
The trick, which is somewhat buried in Apple's settings, is the ability to turn your entire screen red:
Eric Teske/Stellar Neophyte Astronomy Blog
An iPhone screen turned entirely red with iOS 10's new color filter accessibility feature.
In short, this is the equivalent of an approved "night vision" mode for the entire iPhone - a now-crucial tool for backyard astronomers and astrophotographers, says my friend, Eric Teske.
When you're stargazing, you often need to reference interactive star charts, make a quick exposure calculation, or tell a significant other "just one more hour and I'll come back to bed."
"A red tint throughout the entire phone is a quick trick for astronomy and stargazing to preserve dark vision," Teske wrote in a post at his blog, Stellar Neophyte. "Previously, individual astronomy and stargazing apps would let you tint the screen red for night mode, but now you can change the tint of the entire phone."
In the future, this should help Teske work his camera rig in total darkness to take beautiful photos like this shot of the Orion Nebula:
I don't own an iPhone myself, but do love to stargaze with the help of my Android phone - though it can be very frustrating to use.
Before I head out to peek at a conjunction, eclipse, or planet sighting, I toggle the "night vision" mode with Google Sky Map:
Google Sky Map
Night vision mode in Google's stargazing app.
It works well enough - until I accidentally swap apps or cancel out of the program, blast my eyes with harsh white light, and set back my dark-adjusted vision by about 10 to 20 minutes. (Ugh.)
Though apps like Twilight for Android and f.lux for iPhone can change a screen's color tint, they're generally geared toward reducing blue light to improve sleep - not completely filtering out and eliminating colors to preserve night vision. (Apple also pulled f.lux from the app store to replace it with its own in-house version.)
Here's how Teske says you can turn on Apple's new color filters feature to turn your screen red.
From the general settings menu, find and tap "Accessibility," then find and tap "Display Accommodations":
Tap "Color Filters":
And then tap red and set the hue and intensity all the way up:
Teske says he first found out about the feature from Instagram user xt8dob, and notes there's one thing to keep in mind:
"Items that were previously red might disappear completely!" he says.
