InspectCamAndroid
How to keep the flash on while taking a picture
By , developer of InspectCam · Published · Last updated
In photo mode, your phone's flash only fires for the instant the picture is taken, and the first blink is the phone measuring the scene. To keep the light on while you line up the shot, you need a light that stays on: the video-mode trick, a second torch, or a camera app that holds the LED on in photo mode. Then you can see the spot, tap to focus, and take the picture.
It's a question that comes up again and again on phone forums: how do you keep the flash on while taking a picture? You set the flash to On, point the phone into a dark cupboard or under a car, and the light only blinks when you press the shutter. Turn the flashlight (or torch) on first, and on most Android phones it switches off the moment the camera opens.
So you shoot, check the photo, and find half a pipe or the wrong corner. This page explains what flash mode is actually doing, why it blinks twice, and how to keep the light on so you can see the spot before you take the picture.
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What "flash on" actually does
Setting the flash to On tells the camera to fire it for the capture. Android's camera documentation describes that setting as "fire flash for this capture". It's a burst for the photo, not a light for the moments before it.
The same LED has a second mode, which the documentation calls torch: "continuously on". That's the mode you want while you aim. Many camera apps only offer it as a video light, which is why the video-mode trick works and a flash-on photo doesn't.
Why the flash blinks twice
On Android, a flash photo is a two-step job. Before the real exposure, the camera runs what Android's camera documentation calls the precapture metering sequence. When the flash is enabled, that step fires "pre-capture flash pulses to estimate scene brightness and required final capture flash power". Then the photo is taken with the flash it worked out.
So the first blink is measuring, and the second is the photo. The documentation warns developers that a flash photo taken without this step "may be incorrectly exposed", which is why cameras don't skip it.
Red-eye reduction is a separate thing. Android lists it as its own auto-flash mode. Where your camera app offers it and it's on, you may see an extra blink. But a blink before the shot doesn't by itself mean red-eye reduction is running, because the ordinary flash settings do the metering pre-flash too.
This page describes Android. We haven't measured how iPhone sequences its flash, so we don't describe it here.
Why the flash doesn't help you aim
A flash lights one instant: the one where the shutter opens. Everything before it, finding the thing, framing it, deciding what you want sharp, happens in whatever light the space already has. In a dark cavity that means almost none.
You don't see the result until the picture already exists. So you shoot, look, adjust, and shoot again. The pre-flash doesn't change this: it's there to set the exposure, not to show you the scene.
Ways to keep the light on while you take the picture
| Option | Can you see before you shoot? | The catch |
|---|---|---|
| Flash on | No | Lights only the photo |
| Video mode with the flash on | Yes | Photos are frames from the video, at video resolution |
| A torch or headlamp in your other hand | Yes | Needs a free hand, and it's hard to aim two things into one gap |
| Phone flashlight, then open the camera | Usually not | On most Android phones the flashlight switches off when a camera opens |
| A camera app that keeps the light on | Yes | One more app to install |
A second light works well if you have one and a hand to hold it. In a narrow gap, though, the torch and the phone fight for the same opening, and the torch is often lighting something other than what the camera sees.
The phone's own flashlight is the obvious idea, and on most Android phones it doesn't survive opening the camera, because the flashlight and the camera flash are the same LED. The flashlight guide explains why, and its video-mode trick covers a free workaround and its limits.
A camera app that holds the light on is the tidy answer: one device, one hand, and the light points exactly where the camera does.
See it, tap to focus, then shoot
This is how it works in InspectCam, which I build. The light comes on when the app opens and stays on, including through the moment you take the photo. We checked that on a Pixel 6a with the current release; we haven't tested other phones for it yet.
- Open the app. The rear camera is live and the light is already on. There's nothing to switch on.
- Find the spot. Move the phone until you can see what you came for. If you need more of the space in view, the 0.6× button zooms out, on phones whose camera offers it.
- Tap it to focus. Tap the thing you want sharp. You're choosing it with your eyes, in light, rather than guessing.
- Take the photo. No flash fires. The light that let you aim is the light in the picture.
That other phones can't focus in the dark (many use their own tricks, which we haven't measured), or that your photos will come out sharper. What changes is that you can see what you're aiming at before you shoot.
Questions people ask
How do I keep the flash on while taking a picture?
In photo mode you usually can't: the flash is set up to fire for the capture, not to stay on. Your options are the video-mode trick, a second light in your other hand, or a camera app that keeps the LED on in photo mode. With the light already on, you can see the spot and tap to focus before you take the picture.
How do I take a photo with the flashlight (torch) on?
On most Android phones the flashlight switches off the moment a camera app opens, because the flashlight and the camera flash are the same LED and the camera takes it over. You need a camera app that turns the LED on itself and keeps it on in photo mode, or the video-mode trick. The flashlight guide explains why.
Why does my camera flash twice?
On Android, the first flash is part of what the camera documentation calls the precapture metering sequence: short flash pulses the phone uses to estimate how bright the scene is and how much flash the photo needs. The second flash is the one that lights the photo. Where red-eye reduction is switched on, you may see an extra blink as well.
Is the first flash for red-eye?
Not only. Red-eye reduction is a separate, optional flash setting on Android. The metering pre-flash happens with the ordinary flash settings too, so a blink before the shot doesn't mean red-eye reduction is running.
Why are my photos in the dark hard to aim?
Because a flash only lights the instant the picture is taken. Framing the shot and choosing what to focus on both happen before that instant, in the dark, so you find out what you photographed after the fact. With a light that stays on you can see the spot, tap to focus on it, and then take the picture.
Will a light that stays on make my photos sharper?
We haven't measured that, so we don't claim it. What it changes is the order of things: you can see what you're aiming at and tap it to focus before you take the picture, instead of checking afterwards.
Seen your phone do something different? Tell us the model. Flash behaviour varies between camera apps and manufacturers, and a report that contradicts this page is worth having.