helseeffekt

The helseeffekt is a visual artifact characterized by a luminous ring or halo around bright light sources. The term is used in optics and vision science to describe rings or aureoles appearing around light sources in eyes, cameras, or imaging systems, as well as natural halos observed in the atmosphere around the sun or moon.

In human vision, halos arise from diffraction and scattering of light by the eye’s optical media. Variations in pupil size, corneal surface irregularities, cataracts, or dry eye can intensify halos, particularly with bright point sources. They may be temporary and benign, but in some eye conditions halos can indicate pathology.

In photography and imaging, halos are commonly called lens flare or glare. They result from internal reflections and scattering among lens elements, coatings, and the sensor. The shape and color of a halo depend on the lens design, aperture, and shooting angle; artifacts can appear as rings, ghosts, or colored fringing. Techniques to reduce halos include adjusting composition, using a lens hood, applying anti-reflective coatings, changing focal length, or diffusing light sources.

In atmospheric optics, halos are natural phenomena formed by the interaction of light with ice crystals in the upper atmosphere. The 22-degree halo is the most common, appearing as a ring around the sun or moon; related features include sun dogs and circumzenithal arcs.

The helseeffekt can affect visibility and image quality but is also used in artistic photography and meteorology as a diagnostic indicator of optical conditions.