All the light sources are either broken, out of energy, out of fuel (includes wax) or simply not there. The scene is illuminated by a single light. This can be a flashlight or electric lantern, but is usually a lighter, a candle or a matchstick. In caves and dungeons, a single flaming torch. And yet, despite the tiny size and almost insignificant lumen output of the thing, everything looks as if the light was powered by a nuclear reaction. Rooms, even quite large ones, will be lit up to almost daylight level.
If the light source isn't infinite and the matchstick is depleted, or the battery/fuel runs out, the light extinguishes and everything is suddenly pitch black. Cue the monsters, traps or sentimental/sexual plot twist.
As you might've guessed, the humble candle isn't quite so convenient in reality. While they can burn quite bright, their unfocused light only reveals things around them in a loose sphere that degrades with distance; good for the surrounding area, not so much for distance travel. Lanterns being carried on the ends of poles in the olden days wasn't merely for ease of transport, but also so the carrier had a way to hover the lantern in front of them and see where they were going. The pursuit of a better, more reliable means of lighting the way forward is what led to the invention of the common flashlight. But of course, managing realistic lights in settings like action movies and video games would be cumbersome and detract from the more important bits (unless the theme is, say, Survival Horror), so cases where the light is unreasonably bright and/or self-sustaining are typically Acceptable Breaks from Reality.
Compare Absurdly Bright Light. Also see Hollywood Darkness, where the ostensible light source is either natural or completely inexplicable... And usually blue. Often appears in the same context as (and immediately after) By the Lights of Their Eyes – it wouldn't be much of a Reveal if a darkness-shrouded monster stayed darkness-shrouded after the candle was lit.
Contrast Chiaroscuro, where everything looks like it was actually lit by a real candle.
- In the Panty & Stocking with Garterbelt episode "Once Upon a Time in Garterbelt", Stocking strikes a match and instantly illuminates the entire trap-filled catacomb that lies before them. As they dodge trap after trap, eventually the match burns out and the room goes instantly dark again.
- Invoked in Day for Night, where a technician makes a prop to illuminate the face of the lead actress of the Film Within a Film Meet Pamela.
- In Die Hard, the main character is advancing in a ventilation shaft, illuminating his way with a Zippo. The light provided is, however, more akin to a searchlight than to a small flame.
- In The Gunfight at Dodge City, Lily lights a single candle that not only lights up her entire bedroom, but illuminates her face from the opposite side to where it is located.
- The Painted Hills: When Taylor and Tommy enter the darkened cabin where Jonathan is laid up with a fever, Taylor strikes a match that illuminates the entire room.
- In Scary Movie 2, when Cindy shows Buddy the secret study, he lights one candle, which then illuminates nearly the whole room. As this is a parody film, this is likely intentional.
- In What a Carve Up!, Ernie strikes a match that provides enough illumination to light up the whole secret tunnel. Immediately subverted when he falls down a hole in the floor he somehow failed to notice.
- Subtly parodied in Young Frankenstein, when Frau Blücher (WHINNY!) warns the other characters to "stay close to the candles" she is carrying, because the staircase can be treacherous. None of the candles are even lit.
- Journey to the Center of the Earth: After the darkness of the tunnels, the vast cavern containing the Lidenbrock Sea is brightly lit by a mysterious source of illumination, which the explorers presume is from some kind of natural electricity.
- An episode of Friends does this. There is a blackout, and the friends are bringing in candles for light. Later on, all the candles but one are extinguished, and yet the light level is almost the same. One of the characters then blows on this last candle extinguishing it, and everything goes dark. A sentimental plot twist follows.
- An episode of Little House on the Prairie does this very badly. One of the girls is kidnapped and trapped in a pitch-black cellar... when her captor checks on her while holding a small candle, it's suddenly as if a spotlight was shining down.
- Lampshaded in the Painted Hills episode of Mystery Science Theater 3000.
Tom Servo: That match sure lit up the room!
- An episode of the Jennifer Ehle/Colin Firth Pride and Prejudice (set in 1810-ish) has the Bennetts sit down for dinner. The room is brightly lit as if by sunlight, but behind Mr Bennett you can see it's pitch black outside. There's no way candles or oil lamps could produce such perfect light.
- In the Supernatural episode "What Is and What Should Never Be" (S02, Ep20), Dean's flashlight is the only light source in an abandoned warehouse on a rainy night.
- Thunderbirds: In "The Uninvited", the interior of the pyramid is brightly lit, with no lamps visible. At first, this is unexplained, until the party enters the villains' lair, where a complicated fuel system is visible.
- In Rosencrantz and Guildenstern Are Dead, the second act opens in near-darkness. Then Hamlet lights a single oil-lamp, and the stagelights all come on. The stage directions even note that this is highly unrealistic.
- Any ostensible light sources on stage are controlled by the lighting technician whenever possible, so an actor "turning on a lamp" will usually just reach up inside the shade to cue the tech to turn on the visible lamp as well as the (much brighter) stage lighting so that it appears turning on the lamp lit up the stage. Where the tech cannot control the on-stage source (a candle or torch), the staging will include a similar obvious cue for the tech to bring up the lights simultaneously. You really can't expect an audience whose eyes have gotten adapted to 10 kilowatts or so of lighting (and that's actually pretty minimal) to adjust to the light given off by a candle in any sort of reasonable time frame.
A 100-watt bulb seems pretty bright in your living room. The average spot on a theatre stage is probably being hit by at least three 500 watt (or more: 575, 750, and 1000 are also common wattages) instruments, focused to direct their entire output into a fairly narrow cone. You can usually still tell a "practical" fixture (an onstage lamp) is on by looking directly at it, but if you look closely you'll notice it doesn't seem to cast any noticeable shadows.
- Bionic Commando: In the NES version, the Flares illuminate the entire screen in the otherwise pitch dark Area 4. In Rearmed, they instead have a Chiaroscuro effect.
- Doom has the Light Amplification Visor. Its gimmick is simple: turn the brightness of all map sectors to max (known as "fullbright") for two minutes. According to the press release beta, the LAV was meant to work like a set of Night-Vision Goggles by applying a green colormap to the screen, but because the visual engine was limited and the sprites were difficult to discern, this idea was abandoned, although the GZDoom source port brings this back (with some improvements like highlighted monster and item sprites a la Duke Nukem) as a native option.
- Feeding Frenzy 2: Shipwreck Showdown: Anglerfish lures usually are little more than a faint dot in an ocean of darkness. Yet in the Blackout Basement levels, Edie's esca can illuminate a sizeable area around it, and even the entire screen.
- The Legend of Zelda:
- The Legend of Zelda: The Candle items light up dark rooms by tossing a single fireball that burns for only a few seconds.
- Zelda II: The Adventure of Link. If you don't have a candle, you cannot see any enemies in dark rooms, even if they are inches in front of you. Once you get the candle, they're visible even if Link and the enemy are on opposite sides of the screen. Note that orange Daira and orange Lizalfos enemies are an exception to the "invisible in dark rooms" rule (the player wasn't expected to run into them before finding the candle, so their palette was not changed for darkened areas).
- The Legend of Zelda: A Link to the Past: When Link lights up a sconce, the whole room lights up. The only difference between how many sconces are lit is how dim or bright the ambient light is.
- The Legend of Zelda CD-i Games: The lamp in Link: The Faces of Evil and Zelda: The Wand of Gamelon works similar to the candle in Zelda II. One use of the lantern lights up the entire dark area for a limited time, and requires lantern oil.
- Pokémon: The Flash ability does this in early games, lighting up dark caves entirely (what makes some caves pitch-black and others not is never explained). In later games, though, it's just an expanded circle of light around the player.
- Heretic and Hexen have the Torch as a consumable item. It lights up the entire map with a fire-like flickering effect+ . It burns out after about 60 seconds.
- Consciously averted in Ultima Underworld. As you are underground, light sources are important, but the candle is the least useful of them all, providing only a foot or two of vision, compared to the torch or the lantern. The Taper of Sacrifice, however, will never burn out, making it useful despite not being very helpful.