The telescope structure, viewed from the east and from the south The optical configurations and field sizes of the three existing prime focus correctors, drawn to the same scale. The figure of the aspheric plate has been exaggerated in this diagram. Spot diagrams for the doublet corrector, with the axes labelled in mm.
Image quality is good well beyond the spectral range indicated here.
Spot diagrams for the triplet corrector. Images are usable for guiding at all the wavelengths illustrated here, even at the edge of the 1 field. Shaded areas mark the region where sources can be observed either above or below the pole.