Light leaks, halation and vignettes: film's accidents, explained
Three artifacts do most of the work when a photo reads as "shot on film": light leaks, halation and vignetting. Each was a physical accident before it was an aesthetic — and knowing what caused them is the difference between using them well and slapping orange streaks on everything.
Light leaks: the camera's failure
A light leak is exactly that — light sneaking through a worn seal or cracked body and fogging the film, usually as warm orange-red streaks at the frame edge. They mark cheap or aging cameras: toy cameras and battered point-and-shoots leaked; a serviced SLR didn't.
Use them: sparingly, on party/summer/toy-camera looks, where chaos fits. Spot the fake: identical leak, same position, every photo. Real leaks varied with the frame — good presets randomize them.
Halation: the glow around lights
Halation is the soft red-orange bloom around bright light sources — light passing through the emulsion, bouncing off the film base, and exposing the emulsion again from behind. It's most visible in night shots: neon signs, candles, headlights all wear a warm halo.
This is the artifact cheap filters skip, because it must interact with the actual image — which is why it's also the strongest authenticity signal. Cinema stocks made it iconic; the look is now half of what people mean by "cinematic". (Grain, its sibling artifact.)
Vignetting: the darkened corners
Simple lenses passed less light to the frame's corners — so cheap cameras (toy, disposable, instant) vignetted hard, and premium glass barely at all. The eye reads it as focus: the darkened edge pushes attention to the center, which is why even modern portrait modes fake a little of it.
Match it to the camera: heavy vignette on a "professional SLR" preset would be wrong; on a toy-camera look it's the whole point.
Using all three coherently
The artifacts must agree on which camera "took" the photo — that's why per-camera presets beat stacking effect sliders. In Selfie, each of the 50+ presets carries its era-appropriate mix (the disposable leaks and vignettes, the SLR looks halate subtly, the medium-format presets stay clean), applied live at capture, on both cameras in dual mode. (Why capture-time beats editing.)
Common questions
Do these artifacts work on video? Halation and vignette, yes — beautifully. Light leaks on video read as flicker and quickly become a gimmick; VHS artifacts are the period-correct choice for moving footage.
Why do they flatter faces? Vignette centers the subject, halation softens highlights on skin, and none of them add detail — flattery in photography is mostly subtraction.
Can I add halation in editing? Approximations exist, but convincing halation needs the highlight data from capture — blown highlights in a JPEG have nothing left to bloom from.