FoV = Field of View. This may be limited by the size of a CCD or a collection of overlapping frames. In radio interferometry it is ultimately limited by the primary beam of the individual antennae but this is a continuous funtion usually described as FWHM (full width hald maximum). In addition the edges of the field may suffer worse degredation due to time- or spectral-smearing, so the effective field of view is expressed as a sum of functions or as the point at which the worst effect leads to a 10% or 50% etc. degredation.

-- AnitaRichards - 07 May 2004