Film is an imperfect, tangible medium. Some of the brightest minds have been refining it for nearly two centuries, and it still surprises us with its random and organic artifacts today. Before digital photography became widespread, many efforts focused on reducing grain, enhancing clarity, and optimizing color science. Currently, some of the most renowned emulsions maintain the tradition of technological advancement to produce clearer images with less noise. However, in a post-perfectionist era, where achieving clinical image accuracy is relatively simple, film artifacts are now appreciated for their expressive potential and unique representations of reality. One such artifact is halation, which I will thoroughly explain and discuss in this mini-guide. This guide includes: What is halation? What causes halation? The pressure plate does not cause halation. How anti-halation layers function. Which films can create halations? Halation compared to lens bloom and haze. A creative effect. Support this blog & unlock premium features with GOLD memberships! An illustration of the halation effect. Light passes through the film layers and reflects off the boundary between the back of the film and air through total internal reflection—a phenomenon that can make water appear reflective, for example.
What is halation? Halation in photography is an effect that appears as white, red, or orange halos around bright points of light in an image, caused by rays reflecting and scattering around the film layers that are farthest from the lens. In color film, the red-sensitive layer is furthest from the lens, where the halation effect typically occurs; this is why color film often produces red halos. Halation can happen in all types of film, including black-and-white, which shows halation in white. However, it is generally minimized through various anti-halation technologies. Halation in color film can also impart a red hue to the bright areas of an image, for instance, giving overcast skies a slightly pinkish tint.
What causes halation? Photographic film, although thin and flexible, consists of several even thinner layers. As light passes through these layers, it reaches the boundary between the film base and air, resulting in some of the light being reflected back. This phenomenon is known as total internal reflection. You may have observed it when seeing a reflective air surface while looking up from below the water in a pool. Total internal reflection occurs when light rays reflect back at an angle upon reaching the boundary with a less dense medium (e.g., from water to air).
An illustration of total internal reflection at the water/air surface when viewed from below (shot on Nikonos V). Similar to reflections off the water-air boundary observed while diving, light that travels through photographic film can reflect off the interface between the emulsion medium and air. As the light bounces off this boundary, it saturates the first photosensitive layer (which is usually red in color film), creating a halo around the entry point — refer to the illustration above.
It’s not the pressure plate that causes halation. Most online sources suggest that halations result from light reflecting off a camera's pressure plate. However, this did not resonate with me, and a Kodak-trained and certified film processing technician I spoke to on Threads had a similar view. Film pressure plates (metal pieces mounted on a film door that press against film to keep it flat when the camera is closed) typically have a black paint coating. While this coating does not ensure complete light absorption, it is likely as absorbent as the anti-halation layers present in the film itself. Nevertheless, the small air gap between the film and the camera’s pressure plate is unavoidable, leading to total internal reflection (TIR). This is why anti-halation layers are crucial components—without air, there is no TIR! Halations manifest as red halos around bright points of light on CineStill 800T.
Film is an inherently flawed and tangible medium. In today's post-perfectionist era, where achieving precise image accuracy is straightforward, the imperfections of film are now appreciated for their artistic value and distinctive, singular interpretations of reality. One of these imperfections is halation, which I will elaborate on extensively in this mini-guide.