Bokeh
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| Name | Bokeh |
| Type | Photographic phenomenon |
Bokeh is the visual quality of the out-of-focus areas in an image produced by photographic lenses and optical systems. It influences aesthetic perception in portraits, landscapes, and microscopy, and interacts with lens design, aperture geometry, aberrations, and sensor characteristics to yield distinctive blur rendering. Photographers, cinematographers, optical engineers, and artists evaluate bokeh for its impact on subject isolation and scene mood.
Definition and Characteristics
Bokeh refers to how out-of-focus highlights and texture are rendered by a lens and is distinct from depth of field, exposure, and sharpness; practitioners assess bokeh by examining highlight discs, longitudinal blur, and edge transition smoothness. Influential figures and institutions such as Ansel Adams, Henri Cartier-Bresson, Dorothea Lange, Alfred Stieglitz, Magnum Photos, National Geographic Society, and Royal Photographic Society have engaged with blur aesthetics in their work and collections. Key venues and events where bokeh effects are showcased include Venice Biennale, Sundance Film Festival, Cannes Film Festival, Museum of Modern Art, Tate Modern, and Guggenheim Museum. Critics and theorists from Roland Barthes to Susan Sontag have discussed the expressive role of out-of-focus rendering in photographic meaning.
Optical Principles and Causes
Optical roots involve lens aberrations, pupil shape, aperture blades, and wavefront propagation described in the work of Isaac Newton, Christiaan Huygens, Augustin-Jean Fresnel, Joseph Fourier, and Lord Rayleigh. Spherical aberration, coma, astigmatism, and chromatic aberration—studied at institutions like Bell Labs, MIT, Caltech, Imperial College London, and ETH Zurich—alter the point spread function (PSF) producing characteristic blur. Sensor and film interactions, including film grain research at Eastman Kodak Company and sensor microlens arrays designed at Sony Corporation and Canon Inc., further modulate out-of-focus rendition. Optical design methods developed by Carl Zeiss AG, Leica Camera AG, Nikon Corporation, Panavision, and Schneider Kreuznach employ aspherical elements, floating elements, and apodization to control bokeh.
Artistic and Photographic Use
Photographers and cinematographers use bokeh to direct viewer attention, create separation, and evoke atmosphere; notable practitioners include Annie Leibovitz, Richard Avedon, Helmut Newton, Wes Anderson, Christopher Nolan, Roger Deakins, and Emmanuel Lubezki. Portrait studios and agencies such as Vogue (magazine), Harper's Bazaar, Time (magazine), BBC Studios, and Netflix leverage shallow focus and bokeh in editorial and cinematic imagery. Techniques for creating appealing bokeh are taught at Rochester Institute of Technology, International Center of Photography, Royal College of Art, and workshops led by photographers affiliated with Getty Images and Magnum Photos. Commercial products like lenses from Canon EF, Nikon F-mount, Leica M-mount, Sony E-mount, and specialty optics by Lensbaby or Hasselblad are often marketed based on bokeh character.
Measurement, Quality, and Evaluation
Quantification of bokeh employs metrics such as PSF analysis, modulation transfer function (MTF), encircled energy, and circle of confusion criteria used by researchers at SPIE, OSA (Optical Society), IEEE Photonics Society, National Institute of Standards and Technology, and Fraunhofer Society. Laboratories at University of Cambridge, Stanford University, University of Tokyo, and Purdue University publish evaluations comparing lenses from Carl Zeiss AG, Sigma Corporation, Tamron Co., Ltd., Samyang Optics, and Tokina using standardized charts and empirical tests. Industry awards and tests by DPReview, Imaging Resource, TIPA (Technical Image Press Association), and EISA influence consumer perception of bokeh quality, while optical standards discussions occur in committees of ISO and technical symposia such as Photokina and CES.
Historical Development and Notable Examples
Historical milestones trace through early portrait lenses from Daguerre, advances by Joseph Petzval, and lens patents filed by Oskar Barnack, Ernst Leitz, Kassel Optical Works, and companies like Eastman Kodak Company and Voigtländer. Iconic lenses and designs recognized for bokeh include the Helios 44 series, Sonnar (Carl Zeiss) variants, Planar designs, and modern apodization lenses such as those by Minolta and Sony. Cinematic use of shallow focus and out-of-focus aesthetics appears in works by directors like Alfred Hitchcock, Stanley Kubrick, Orson Welles, David Lynch, and Stanley Donen, with cinematographers such as Sergio Leone collaborators influencing popular taste. Collections and retrospectives at Getty Museum, Metropolitan Museum of Art, Centre Pompidou, and Los Angeles County Museum of Art document shifts in aesthetic preference toward or away from pronounced blur.
Technical Variations and Lens Design Factors
Lens elements, aperture geometry, diaphragm blade count, aspherical surfaces, and apodization filters produce variations: designs by Otto Schott glass makers, coatings from Perth Optical, and optical formulas used by Nikkor, Fujinon, Zeiss Planar T*, and Sigma Art series demonstrate trade-offs. Specialized optics such as tilt-shift lenses sold by PC-E Nikon and Tilt-Shift Canon and soft-focus lenses used in studio portraiture exemplify controlled bokeh manipulation. Advances in computational photography by teams at Google Research, Apple Inc., Facebook AI Research, Adobe Systems, and NVIDIA integrate depth estimation and synthetic bokeh rendering into smartphones like Apple iPhone, Google Pixel, and Samsung Galaxy series, combining optical and algorithmic approaches.