Close-up lens attachment placed in front of the lens to reduce minimum focus distance, enabling extreme macro shots without swapping lenses.
Technical Details
Diopters are available in strengths from +0.5 to +10, with +1 to +4 diopters being sufficient for most cinematic applications. A +2 diopter lens, for example, reduces the minimum focus distance of a 50mm lens from 45cm to approximately 22cm. The lenses are made of optical glass with multi-layer coating and are available in standard filter threads (52mm to 95mm) or as 4x5.65" matte box filters. Achromatic diopters correct chromatic aberration through two cemented lens elements of different dispersion.
History & Development
Diopters emerged in the 1920s parallel to the development of macro photography. Leica introduced the first series-produced diopters for 35mm cameras in 1930. In film production, they became established from the 1940s onwards, as Technicolor productions demanded detailed close-ups of jewelry and props. Tiffen developed the first achromatic diopters specifically for the film industry in 1965. Modern variants utilize ED glass (Extra-low Dispersion) and nano-coatings for minimal reflections.
Practical Use in Film
Ridley Scott used +3 diopter lenses for the iconic alien egg sequences in "Alien" (1979) to achieve extreme close-ups at a 35mm focal length. David Fincher used +2 diopters in "Zodiac" (2007) for detailed shots of newspaper prints without having to reposition the camera. The workflow requires precise focus pulling, as the depth of field decreases by approximately 50% with +2 diopters. Advantage: Quick switching between normal and macro shots without changing lenses or camera.
Comparison & Alternatives
Compared to extension tubes, diopters offer the advantage of maintaining lens aperture, but they produce visible field curvature at strengths above +2 diopters. Macro lenses deliver optically superior results but require lens changes and are more expensive. Modern alternatives include variable diopter systems such as the Panavision Close Focus System, which allows stepless diopter adjustment from +0.25 to +2. For Ultra HD productions, macro primes are increasingly preferred over diopters, as they do not involve optical compromises.