What is halation?
Halation is a soft, often reddish or orange glow that appears around bright highlights and high-contrast edges on film, such as street lamps, neon signs, or sunlit windows against dark surroundings. It is an optical effect of the film itself rather than of the lens, and many people consider it part of the look of analogue photos and motion picture film.
How halation happens
Film is made of light-sensitive layers on a transparent base. Very bright light can pass right through the emulsion layers and reach the back of the film. There it can reflect off the base surface or the camera’s pressure plate and travel back into the emulsion, exposing it a second time slightly away from where it first arrived. The deepest layer in colour film is usually sensitive to red light, which is why the glow tends to look red or orange. In black and white film the effect appears as a soft white halo.
Silver halide crystals, including silver bromide (AgBr), are the light-sensitive compounds in most photographic emulsions. They are not the cause of halation itself, but they are what records the stray light.
Anti-halation layers and remjet
Most films include an anti-halation layer that absorbs light before it can reflect back. Many motion picture films use a dark carbon-based layer called remjet, which is removed during processing. Some still films use a dye layer that washes out in development.
Certain specialty films leave this layer out or reduce it so they can be developed in standard C-41 chemistry. CineStill 800T is a well-known example, and its red glow around bright lights is a signature part of its look. Other films show halation to a lesser degree, and the strength varies by emulsion and by how bright the highlight is.
Halation vs bloom and flare
- Halation comes from light reflecting inside the film and is mostly red or orange in colour film.
- Bloom is a general softening or glow around highlights that can come from the lens, filters, or processing.
- Lens flare comes from light scattering inside the lens and can produce streaks, rings, or haze.
Because the origins differ, they can overlap in the same picture, so it is not always easy to tell which effect you are seeing.
Shooting for halation
You cannot add halation with a normal film camera, but you can choose subjects and films that show it.
- Pick a film with a weak or removed anti-halation layer, such as CineStill 800T, if you want a strong effect.
- Shoot at night with bright, small lights against dark backgrounds, such as signs or car headlights.
- Expose properly for the scene rather than the lights, since halation grows with highlight brightness and exposure.
- Keep the lens clean, since dirt adds its own flare that mixes with the glow.
Exposure basics still apply, so see our guide to exposure on a film camera for metering tips in tricky light.
Digital halation
Digital sensors do not produce halation in the same way, so digital photographers and filmmakers add it in editing. Software and plug-ins can blur and tint highlights red or orange to imitate it. The result can be convincing but is an approximation, because real halation depends on the film and the scene.
Related questions
What is the 60/30/10 rule? It is a design guideline about colour balance, with roughly 60 percent of a scene in a dominant colour, 30 percent in a secondary colour, and 10 percent in an accent. It is not related to halation.
What is noise in photography? Noise is random variation in brightness or colour that looks like speckles. On film it appears as grain, and on digital sensors it appears as electronic noise, especially at high ISO. Halation is a different effect and does not create noise.