A skylight filter is a filter that is used in photography . It is a weak conversion filter , which gives the picture a slightly reddish color and thus ensures warmer color reproduction. The skylight filter is usually screwed onto the front of the lens . With some special lenses, it is inserted into the optical path or screwed in using a filter turret.
It makes sense to use it in landscape photography, for example , since distant objects such as mountain ranges are colored slightly blue by the refraction of light in the atmosphere (see Rayleigh scattering ). The skylight filter counteracts this.
However, when exposing negative films, this effect is often neutralized, for example when the print is optimized by the laboratory. So the final colors depend more on the image processing of the enlargers than on lightweight filters.
Like many other filters, the skylight filter also acts as a UV blocking filter .
In addition to the advantages listed above, skylight filters have the disadvantage that, like any filter, they reflect light that is reflected from the front lens back into the lens and can thus create unsightly light points ( lens flares ) on the recordings when taking backlit photos . However, there are also so-called ghostless skylight filters, the glass of which is not flat, which reduces the flare effect. A low-quality skylight filter can also cause a subjectively detectable reduction in contrast in high-contrast situations.