There’s a little-known but awesome trick you can do with the iPhone’s camera: triple-click the Home button to turn it into a magnifying glass. This is great if you don’t see so well, either because you’re farsighted or because you’re just getting old and doddery.

Today we’ll see how to switch on this awesome feature so it’s ready to deploy, and also take a look at some of the extras Apple built in to make the Magnifier tool even more powerful.

How to switch on the iPhone Magnifier

First off, here’s how to switch it on. Go to Settings>General>Accessibility>Magnifier and tap the switch to activate it. While you’re there, you might also want to toggle the Auto-Brightness on, which will let the Magnifier control the screen brightness even if you usually have it set to manual.

Now, when you triple-tap the Home button, the Magnifier activates. Unless, that is, you have another function already assigned to the triple-tap. I have my iPad set to invert the screen colors with the triple-tap, so when I do the tapping, I see this:

This dialog lets you choose which function to activate. On my iPhone, I set the Magnifier as the sole triple-tap option, which is the default if you haven’t already been messing around with things.

When you activate the iPhone Magnifier, you will see a zoom slider, a button to activate the LED flash lamp, a button to access the filters, and a big freeze button, which looks like the camera shutter button. This last item might be the most useful improvement over a standard magnifying glass, because it lets you, say, capture text to read without having to hover over the original document trying to hold everything steady.

Improve readability with color filters

The filters are neat, too. The basic controls adjust contrast and brightness, and the color filters allow you to adjust the image (to compensate for colorblindness or just to make things easier to see). High-contrast red-and-black, for example, is great for low-light conditions where you don’t want to ruin your night vision.

The iPhone is an impressive accessibility tool, but sometimes the functions designed to help out the blind, the deaf or folks with other accessibility problems turn out to be very useful for everyone.

The Magnifier is a great example of this. I use it all the time. Not for myself, of course. I use it to snap zoomed pictures and show them to old people.