  Vignetting in camera lenses is generally seen as something to avoid. For
spectral cameras with thin-film interference filters, however, we argue that
vignetting can be an advantage. When illuminated by focused light, the
bandwidth of interference filters increases with the chief-ray angle, causing
position-dependent smoothing of the spectra. We show that vignetting can be
used to reduce smoothing and preserve important spectral features. Furthermore,
we demonstrate that by adding additional vignetting to a lens, measurements can
be made more consistent across the scene. This makes vignetting a useful
parameter during spectral camera design.
