UE5 Lighting Basics: Four Light Types, Lumen, and Fixing a Dark Screen

You place one light in your level and multiply its intensity by ten. The screen barely changes. Turn it off and it doesn't go pitch black either, just dim.

UE5 lighting is the product of four things working together: the light sources, Mobility, Lumen, and exposure. Touch only one of them and the result won't move, which is why it feels unresponsive at first. This article covers choosing between the four light types, what Mobility actually decides, the Lumen that's already running by default, and how to stop auto exposure, the usual culprit behind "too dark" and "too bright."

What You'll Learn

• Choosing between the four lights ( Directional / Point / Spot / Rect )
• Mobility decides "bake it, or compute it on the spot"
• What Lumen, running by default in UE5, is doing
• The culprit behind "too dark" is often auto exposure, not the lights
• Hands-on: lighting a pitch-black cave with three lights

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Choosing Between the Four Lights

The "Lights" section of the Place Actors panel lists five entries, and we'll start with the four that emit direct light (the remaining Sky Light comes later). They differ in how the light is emitted, so mapping each to a real-world equivalent makes the choice obvious.

Light	How It Emits	Real-World Equivalent	Main Uses
Directional Light	Parallel rays. Position is irrelevant, only direction matters	The sun	The key light outdoors. Usually one per level
Point Light	From one point in all directions	A bare bulb, a campfire	Interior lighting, torches, glowing props
Spot Light	A cone in one direction	A flashlight, stage lighting	Guiding the player, drama, car headlights
Rect Light	From a rectangular surface	A window, a fluorescent panel, a monitor	Window light, soft interior light

Only Directional Light ignores its position entirely. Like the sun, it's treated as arriving in parallel from infinitely far away. Only intensity, direction, and color matter. Rotating it is literally changing the time of day.

The first property to touch on Point and Spot lights is Attenuation Radius. It isn't brightness, it's the hard cutoff of the light's influence, and nothing outside that sphere receives any light at all. When "I placed a light but the floor isn't lit," this radius is usually too small.

A freshly placed Point Light defaults to Intensity 8.0 cd and Attenuation Radius 1000.

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What Mobility Decides

Every light has a three-way Mobility choice at the top of its Details panel. This is confusing for beginners, but what it decides is when the lighting is calculated.

Mobility	When It's Calculated	What You Can Do	What You Can't
Static	Baked at build time	Cheapest by far	Can't be changed at all at runtime
Stationary	Partly baked, partly live	Change color and intensity at runtime	Can't move. Limited overlap count
Movable	Computed live every frame	Move, flicker, anything	Most expensive

There's an important precondition in UE5. With Lumen enabled, baked results from Static lights aren't used as GI. Lumen and baked lightmap GI can't coexist, and Lumen takes priority.

That leaves you with two options.

Approach	Light Mobility	Build Lighting
Use Lumen (UE5 default)	Movable or Stationary	Not needed
Go back to baking	Mostly Static	Required (disable Lumen first)

For solo development, building with Movable is the realistic choice. UE5's Lumen assumes dynamic lighting, so leaving everything Movable still produces good-looking results.

"I set it to Static and everything went black" happens when you've chosen the baking approach but haven't run Build Lighting. If you're still on Lumen, there's no reason to set anything to Static in the first place.

Note: Mobility exists on Static Mesh Actors too, not just lights. Leave a mesh you intend to move set to Static and its shadow freezes in the wrong place. Set moving objects to Movable on the mesh side as well.

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Lumen: Light You Didn't Place Bounces In

Lumen is enabled by default in UE5's standard templates. It's a dynamic global illumination (GI) system, and in one sentence, it calculates light bounces automatically.

Shine white light on a red wall and the floor in front of it picks up a faint red tint. Light through a window brightens a ceiling it never directly touches. Lumen generates this light you never placed in real time.

Lumen covers two things.

Feature	Project Settings Entry	Effect
Dynamic Global Illumination	Dynamic Global Illumination Method	Light bounces. Shadows don't go pure black
Reflections	Reflection Method	Reflections. Surroundings appear in floors and water

Both are active as long as they're set to Lumen. Check under Edit > Project Settings > Engine > Rendering.

Thanks to Lumen, a space reads properly without placing dozens of lights. One light travels along walls and floors to fill the area.

Note that "cranking a light barely changes anything" is usually not Lumen's doing. It's auto exposure, covered next.

The Culprit Behind "Too Dark" Might Be Exposure

The other, more common cause is auto exposure (Eye Adaptation).

By default, UE's camera adapts to brightness like a human eye. Go somewhere dark and things gradually become visible; go somewhere bright and the glare settles down. Because this is running, turning a light up just makes the camera stop down and restore the original brightness.

Before tuning lighting, turn this off.

1. Place a Post Process Volume in the level from Place Actors
2. Check Infinite Extent (Unbound) in the Details panel (so it applies to the whole level)
3. Open Lens > Exposure
4. Set Min EV100 and Max EV100 to the same value (both 1.0, for example)

Brightness is now locked, and the screen changes exactly as much as you change the lights. Start every lighting session by disabling exposure. Do it in the other order and every change looks like it's being cancelled out.

Note: Whether you restore auto exposure for the final build is a creative call. The glare of stepping from a cave into daylight is a great effect, but it also changes UI legibility. Finer exposure control is covered in the Post Process Volume article.

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Hands-On: Lighting a Pitch-Black Cave with Three Lights

A horror game cave, a dungeon RPG corridor, an escape-room warehouse. How to present a dark interior is something every genre runs into. Let's build "visible darkness" in a space with no sun, using only three lights.

The Finished Result

A pitch-black space becomes one where the area around a torch glows warm and an exit shines in the distance.

Reproduction Setup

Create a new project from the Third Person template, open a new level via File > New Level > Basic, and get it into this state.

Step	Contents
1	Place a Player Start and set World Settings' GameMode Override to BP_ThirdPersonGameMode (without this you can't walk)
2	Delete the default Directional Light (remove the sun)
3	Delete Sky Atmosphere, Volumetric Cloud, and Exponential Height Fog too (we're indoors)
4	Keep the Sky Light (it's in the Basic level by default. We'll use it later)
5	Stretch the default Floor into a corridor and build walls and a ceiling from Cubes
6	Place a Post Process Volume, enable Infinite Extent (Unbound), and set Min EV100 and Max EV100 both to 1.0

Hit Play at this point and the screen is nearly pure black. Now we add three lights.

Light 1: Lift the Floor with Sky Light

Select the Sky Light already in the level rather than adding a new one (adding one gives you two and unexpected brightness) and change its settings.

Property	Value
Mobility	Movable
Source Type	SLS Specified Cubemap
Cubemap	Any reasonably bright HDRI cubemap (if you have none, turn off Real Time Capture and adjust with Intensity Scale)
Intensity Scale	0.1

Warning: After deleting Sky Atmosphere, leaving Source Type on SLS Captured Scene means it captures a now-black sky and emits almost no light. That's the reason behind "I added a Sky Light and nothing changed." Either specify a Cubemap or make sure there's something to capture.

Shadows that were pure black now lift to just barely readable silhouettes. Set this to 0 and unlit areas become total black, leaving the player unable to judge anything. "Dark" and "invisible" are different things, and this one light draws that line.

Light 2: A Torch Point Light

Place a Point Light partway down the corridor.

Property	Value
Mobility	Movable
Intensity Units	Candelas (cd)
Intensity	50.0 cd
Attenuation Radius	400.0
Light Color	Toward orange (around R 1.0 / G 0.6 / B 0.3)

The Attenuation Radius sphere is the hard limit of influence. Drop the radius to 200 and you can see the light reaching only the player's feet. Move it around to get a feel for how far light carries.

Brightness falls off with the square of distance. At 50 cd you get roughly 50 lux at 1 m and about 12 lux at 2 m. When something is "darker than expected," multiply Intensity by 4 rather than 2 to match one step of distance.

Light 3: A Spot Light Guiding to the Exit

Place a Spot Light at the far end of the corridor, aimed from the exit back toward the player.

Property	Value
Mobility	Movable
Intensity Units	Candelas (cd)
Intensity	500.0 cd
Attenuation Radius	1500.0
Inner Cone Angle	20.0
Outer Cone Angle	40.0

The gap between Inner and Outer is how soft the edge is. Set them equal for a hard outline; widen the gap for a softer falloff (defaults are Inner 0 / Outer 44).

Reaching far takes numbers much larger than a Point Light's. To light something 10 m away, start in the hundreds of candelas.

Verify It

Hit Play and walk the corridor. If the walls turn orange as you approach the torch, fall back into bluish gloom as you leave, and a white exit glows in the distance, it worked.

• Nothing changes at all → The Post Process Volume's Infinite Extent (Unbound) isn't checked
• Cranking intensity doesn't brighten anything → Min EV100 and Max EV100 are still different values (exposure is still moving)
• Only the area right by the light glows and the floor stays dark → Attenuation Radius is too small
• Shadows are pure black and nothing is readable → The Sky Light's Source Type is still SLS Captured Scene. With the sky deleted, it's capturing pure black
• You can't walk at all → GameMode Override isn't set, or there's no Player Start
• Everything is oddly bright → You added a second Sky Light (check the World Outliner)

Now try deleting just the torch Point Light. The orange bounce light on the surroundings disappears with it. Making the walls reddish makes the Lumen bounce difference much more obvious.

Two things to take away.

• The darker the space, the more you need a "floor-raising" light: Before your hero light, use a Sky Light to establish a minimum brightness. Without it, unlit areas go pure black and the player can't even tell whether there's a wall there
• Attenuation Radius decides the range: Point and Spot lights never reach outside their radius no matter how high Intensity goes. When "it won't get brighter," suspect the radius before the intensity

Once the lights are placed, the final pass is color and tone. Balancing the overall look continues in the Post Process Volume article.

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Checks for When Lumen Isn't Working

When "there's no bounce light" or "reflections are pure black," check these in order.

Where to Check	What to Look At
Project Settings > Rendering	Is Dynamic Global Illumination Method set to Lumen?
Same	Is Reflection Method set to Lumen?
Same	Is Generate Mesh Distance Fields on? (required to run Lumen with Software Ray Tracing)
Mesh size	Extremely small objects and thin planes are hard for Lumen to pick up
Project age	Projects migrated from UE4 may not default to Lumen
Target platform assumptions	Lumen is on by default only for desktop-targeted projects created at Maximum quality. Mobile / Scalable / VR / Forward Shading don't qualify

Toggling Generate Mesh Distance Fields requires an editor restart. If a setting doesn't take effect, restart and try again.

Also, if you've enabled Hardware Ray Tracing on a supported GPU, Lumen traces the meshes directly and depends much less on Distance Fields. Still, if you want a fallback for unsupported hardware, leaving it on is the safe choice.

The Lit > Lumen menu at the top left of the viewport offers visualization modes for Lumen's internal representation. That's how you confirm whether it even knows an object is there.

Bonus: Good to Know for Later

• Outdoors means the trio of Directional + Sky Light + Sky Atmosphere: You only get a natural outdoor look with all three. Without a Sky Light, shade goes unnaturally black
• Intensity units differ per light type: Directional Light is fixed to lux. Point / Spot / Rect let you pick cd (candelas), lm, or Unitless via Intensity Units, and the standard default is cd. The same "10" means different things, so don't copy numbers between light types
• Stacking lights gets expensive: Movable lights that cast shadows are especially costly. For small decorative lights, just disabling shadow casting (Cast Shadows) saves a lot (see the profiling article)
• Emissive materials emit light too: With Lumen enabled, indirect light from self-illuminating materials spreads to the surroundings. That's how you get the "bleed" of neon and magic circles. But they're no substitute for a key light. You need Emissive values well above 1, small bright surfaces flicker easily, and they can't produce sharp shadows. Pair them with an actual light where you need reliable illumination (see the material article)
• If you want to place a lot of lights, there's a dedicated system: MegaLights changes the very premise that "more movable lights means heavier." It lets a large number of dynamic lights cast shadows without falling apart, making neon streets, dozens of torches, or heavy spell VFX practical. Check Project Settings → Rendering to see whether it's available in your version (it has hardware requirements)
• If it's heavy, move to baking: This can cut runtime cost dramatically. But disable Lumen first (set Dynamic Global Illumination Method to None in Project Settings and enable Allow Static Lighting). Then set the lights that never move to Static and bake with Build Lighting Only. Rebaking takes time, so save it for after the level layout is settled

Summary

• There are four main direct lights. Directional cares only about direction; Point/Spot/Rect have Attenuation Radius as their hard limit of influence
• Mobility is "when the lighting is computed." While using Lumen, stay on Movable/Stationary, since Static baking can't coexist with it
• UE5 has Lumen on by default. Bounce light you never placed fills the space automatically
• The culprit behind "too dark" is usually auto exposure. Match Min EV100 and Max EV100 to stop it before you tune anything
• Dark spaces need a floor-raising Sky Light. "Dark" and "invisible" are different things

In the level you're building, where's the thing you most want the player to notice first? Start by putting one light there.