A lens flare that streaks horizontally across the frame, caused by a light source entering the lens from the side.
Technical Details
Horizontal flare primarily occurs with focal lengths over 85mm and apertures between f/1.4 and f/2.8 when light sources with an intensity above 3200K strike the front lens laterally. Zoom lenses with more than 12 lens elements are particularly susceptible, as the probability of internal reflections increases exponentially. In digital cameras, the effect is amplified by the reflective properties of CMOS and CCD sensors. Anamorphic lenses, due to their cylindrical lens elements, produce particularly striking horizontal flares with a characteristic bluish tint in daylight.
History & Development
The term became established in 1967 with the introduction of Panavision Primo lenses, which produced new types of flare due to their complex coated elements. Cinematographer Gordon Willis systematically documented horizontal flares during the filming of "The Godfather" (1972) and defined their technical parameters. The digital revolution from 2005 onwards amplified the phenomenon through the higher light sensitivity of CMOS sensors. Modern anti-reflective coatings like Zeiss T* (since 2008) reduce horizontal flares by up to 78% compared to uncoated lenses.
Practical Application in Film
Christopher Nolan consciously utilized horizontal flares in "Interstellar" (2014) with modified IMAX lenses to visualize the vastness of space. Denis Villeneuve specifically employed 1970s Canon K35 lenses in "Blade Runner 2049" (2017), whose uncoated elements create characteristic horizontal flare effects. The technique works optimally in backlight setups with a light-to-shadow ratio of at least 1:8. Undesired horizontal flares can be eliminated using matte boxes with side flags or polarizing filters.
Comparison & Alternatives
Horizontal flare differs from vertical lens flare by its orientation parallel to the image axis and its more uniform light distribution. While anamorphic flares produce characteristic blue lines, horizontal flare typically appears in warm tones between 2800K and 4200K. Digital post-production tools like DaVinci Resolve have offered specialized de-flare algorithms since version 17 that can specifically remove horizontal artifacts. Vintage lenses such as Cooke Speed Panchros produce more organic horizontal flares than modern computer-optimized lenses.