It is obvious that collimated imaging through Fabry-Perot filters is to be preferred when diffraction limited imaging is attempted. The advantages of telecentric imaging (uniform spectral transmission across the field-of-view) are
then not longer possible. In case of the use of adaptive optics for diffraction limited imaging, the isoplanatic patch, however, limits the field-of-view to only a few arcsec anyway, so that the variation of the filter transmission across the field-of-view is minor.