Question 1

How does a browser magnifier work?

Accepted Answer

We open the rear-facing camera with getUserMedia and apply a CSS transform scale() to the video element — 1× through 8×. The browser handles GPU-accelerated upscaling so it stays smooth. We also try to pin the camera's autofocus to 'continuous' so close-up text stays sharp. Some phones expose a true optical zoom range via MediaTrackConstraints.zoom; when that's available we use it for the first 2–3× instead of digital scaling, which gives a noticeably sharper image.

Question 2

Why is the magnified image blurry?

Accepted Answer

Two reasons. (1) Phone cameras have a minimum focus distance — typically 8–10cm. Hold the phone too close to the object and it can't focus at all. Pull back to about a hand-span. (2) Above 3× zoom you're past the optical limit of most phones and into digital scaling, which can't add detail the sensor didn't capture. Use the torch toggle to add light (sharper autofocus), and steady the phone against a surface to avoid motion blur.

Question 3

Why doesn't the torch button do anything on my iPhone?

Accepted Answer

iOS Safari does not expose the rear-camera torch to web pages — it's a privacy/hardware decision Apple has not reversed. On Android Chrome and Edge the torch is available via the ImageCapture API (MediaStreamTrack.applyConstraints with advanced: [{ torch: true }]). If you're on iPhone, our fallback brightness slider helps a little, but to actually light up the subject you'll need to open the Control Center torch first and then return to this page.

Question 4

Is this a real magnifying glass replacement?

Accepted Answer

For reading small printed text — yes, easily. For inspecting fine mechanical detail (watch movements, PCB solder joints, jewelry) — only up to about 3×, after which digital zoom becomes mushy. The advantage over a physical loupe is the built-in light and the ability to take a screenshot of what you're looking at. The disadvantage is the minimum focus distance of phone cameras (you can't get as close as a 10× loupe lens).

Question 5

How is this different from the phone's built-in Magnifier?

Accepted Answer

iOS Magnifier (Accessibility → Magnifier) is excellent and we recommend it on iPhone for serious use. This web version is for (a) Android phones, where the equivalent feature is buried or missing depending on manufacturer; (b) laptops with a webcam, where you might want to inspect something held in front of the screen; and (c) anyone who doesn't want to dig through Accessibility settings to enable a feature they need once.

Question 6

The camera fails to open — what's wrong?

Accepted Answer

Most common cause: another app or tab is using the camera. Close FaceTime, Zoom, Teams, Snapchat, and any other browser tabs that might have requested it, then reload. On Windows laptops the privacy shutter switch sometimes physically blocks the lens — check for a sliding cover. If the page shows 'NotAllowedError', the browser is blocking the camera at the site level: click the camera icon in your address bar and choose Allow.

Magnifier.