Anastigmat

Anastigmat as an optical lens system (eg, a lens ) means that compensates a previously notorious aberration, astigmatism ( Punktlosigkeit ). The correction of astigmatism is achieved primarily that the sagittal and the meridional image surface to be reconciled. This is not physically accessible by the individual lenses. However, in order for an anastigmatic lens may be referred to as anastigmat, and the curvature of field to be eliminated.

The first anastigmatic lens was developed in 1890 by Paul Rudolph for Zeiss four-element Protar. The easiest Anastigmat is a little later developed Cooke triplet of a convex, a concave and a convex lens further. On the Cooke triplet build on other important objectives, such as the four-element Tessar type. Here, the rear lens has been replaced by a cemented lens combination (positive refracting concave- convex combination).

Lenses manner of a Gaussian lens doublet are also usually anastigmats. Originally, these were to strictly symmetrical, and later to more complex, non- symmetric designs.

All high-quality lens systems today are designed as anastigmats. It often involves variants of the triplet or the Gaussian type. Exceptions are special cases in which only a small field of view is imaged as lenses of telescopes and binoculars.

In particular, older camera and projector lenses wear either directly the term " Anastigmat " (eg the Novotrinast - Anastigmat Ed Liesegang oHG. ) Or be an equivalent property resonate ( Patrinast, also a projection lens of Liesegang; Trinast from Carl Zeiss ). Often it involves lenses on the type of Cooke triplets. The pictured Unofocal Double Anastigmat CA However Steinheil follows a Gaussian type.