Schmidt camera optical axis of the Schmidt design creates a Schmidt-Newtonian telescope. The addition of a convex secondary mirror to the Schmidt design directing light through a hole in the primary mirror creates a Schmidt-Cassegrain telescope. The last two designs are popular with telescope manufacturers because they are compact and use simple spherical optics. A short list of notable and/or large aperture Schmidt cameras. Schmidt camera A Schmidt camera, also referred to as the Schmidt telescope, is a catadioptric astrophotographic telescope designed to provide wide fields of view with limited aberrations. The design was invented by Bernhard Schmidt in 1930. Some notable
Gregorian chant 'Alleluia'. The Alleluia is also in two parts, the alleluia proper and the psalmverse, by which the Alleluia is identified (Alleluia V. Pascha nostrum). The last melisma of the verse is the same as the jubilus attached to the Alleluia. Alleluias are not sung during penitential times, such as Lent. Instead, a Tract is chanted, usually with texts from the Psalms. Tracts, like Graduals, are highly centonized. Sequences are sung poems based on couplets. Although many sequences are not part of the liturgy and thus not part of the Gregorian repertory proper, Gregorian sequences include such well-known chants as "Victimae