Quick answer: Unreal adjusts brightness automatically, like your eyes. To lock it:
- Add a Post Process Volume and tick Infinite Extent (Unbound).
- Under Lens > Exposure, tick Min EV100 and Max EV100 and set both to the same value.
- To find a good value, check the scene’s current value with Show > Visualize > HDR (Eye Adaptation).
- Fine-tune the overall brightness with Exposure Compensation.
Why the brightness keeps changing
Auto exposure (eye adaptation) is on by default. Unreal measures how bright the image is and brightens dark views or darkens bright ones. Looking at the sky darkens everything, and walking indoors slowly brightens the room. That’s useful in games, but distracting when you’re lighting a scene or making a cinematic.
Step 1: Lock the exposure
- Drag a Post Process Volume into the level from Place Actors (or the + menu).
- Tick Infinite Extent (Unbound) so it affects the whole level.
- Under Lens > Exposure, tick Min EV100 and Max EV100.
- Give them the same value. Higher values make the image darker.
Locking the range keeps it predictable. If you only want gentler changes, give Min and Max a small gap and lower Speed Up and Speed Down instead.
Step 2: Find the right value
- Open Show > Visualize > HDR (Eye Adaptation).
- Walk to a view that looks right and note the value it reports.
- Use that value for both Min EV100 and Max EV100.
Switching Metering Mode to Manual also locks exposure, but by default it then uses the camera’s ISO, shutter speed and aperture (Apply Physical Camera Exposure). With Unreal’s default light values, that can make the scene almost black. Locking Min and Max is easier to start with.
Editor and Play look different?
| Cause | Fix |
|---|---|
| The viewport uses its own fixed exposure | In the viewport’s Lit menu, under Exposure, tick Game Settings |
| The Post Process Volume only covers part of the level | Tick Infinite Extent (Unbound) |
| A camera has its own post-process settings | Check the Camera Component’s Post Process section, which overrides the volume |
| Project-wide default | Project Settings > Rendering > Default Settings > Auto Exposure |
Bright windows and dark rooms in one shot
When an interior with bright windows has blown-out highlights and crushed shadows, lock the exposure for the room. Then use Lens > Local Exposure to lower Highlight Contrast Scale and Shadow Contrast Scale (try 0.8). This evens out the image without changing the overall exposure.
FAQ
What does “Extend default luminance range” do?
It’s on by default in UE5 projects. It makes the Exposure settings use EV100 values, which match real camera exposure. Leave it on unless you follow an older UE4 tutorial that uses the old values.
Why is bloom stronger in dark scenes?
Auto exposure brightens dark scenes, which also brightens bright spots. Lock the exposure first, then tune bloom. See Bloom too strong or not showing.
Should I turn off auto exposure in my game?
Not always. Players expect some adaptation when moving between indoors and outdoors. A narrow Min to Max range with slower speeds often feels best.