Shutter Speed

Lightbox

Last updated: 2026-09-26

What it does

Turns your screen into a light: soft fill, a catchlight shape for portraits, a colored gel, or a moving color for light painting. On iPhone it can also drive the rear LED torch.

What you need

Nothing beyond the device. It works offline. On web the screen light works, but the app cannot change your display's brightness, so turn your screen brightness up yourself. The Torch tab only appears on a device with a rear LED.

How to use it

  1. Open Lightbox. The whole screen becomes the light, with a controls sheet at the bottom. Tap the handle to hide or show the controls.
  2. Set Brightness at the top of the sheet.
  3. Pick a tab:
    • Color: under Basic, choose Red, Amber, White, or Custom. White adds a Color temperature slider (2700 K to 6500 K) and Gel chips (CTO, ½ CTO, ¼ CTO, CTB, ½ CTB, + Green, − Green). Custom adds a Hue slider. Under Sky, choose Golden hour, Blue hour, or Moonlight.
    • Shape: under Fill, choose Full or Window light (set Light from to Left, Right, Top, or Bottom). Under Celestial, choose Moon (with a Phase slider and a NASA Imagery switch), Sun, Eclipse, or Star. Under Catchlight, choose Softbox, Strip, or Window pane. Adjust sets Size and Softness.
    • Effects: under Mode, choose Steady, Strobe (set Flash rate), SOS, or Paint (choose Rainbow sweep or Pulse and set Cycle length). Shutter timer sets a Delay and a Stay on time; tap Start timer. Under Screen, Keep screen awake stops the display from sleeping.
    • Torch (iPhone with a rear LED): switch On, pick a Mode (Steady, Strobe, or SOS), and use the torch's own Shutter timer. Black screen turns the display black while the torch is on, so only the torch lights the scene.
  4. Tap Lock so a stray touch cannot change anything. Press and hold to unlock.
  5. The reset button next to the tabs puts every setting back to its default after you confirm.

Reading the results

There is no readout. The screen itself is the result. Your settings are saved, so the light comes back the way you left it.

The first time you pick a flashing mode (Strobe, SOS, Paint with Pulse, or the torch's Strobe or SOS), a Flashing light warning appears. Flashing is capped at 3 flashes per second.

When a shutter timer finishes, the light turns off and the screen says so.

Tips

  • Match your camera's white balance: set White to the scene's color temperature (about 3200 K under tungsten, 5600 K in daylight) so the fill does not add a color cast.
  • Use Red at a dark site to keep your night vision.
  • For catchlights, hold the device just out of frame at eye level. Moving closer makes the light brighter and softer.
  • For light painting, set the timer's Delay to your camera's self timer and Stay on to your exposure, then tap Lock.