Low-light-level, integrating television cameras are mounted on the
finder and the Cassegrain focus of the main telescope. Picture
integration is possible either on the camera target or in digital
memory. A Grinnell image display is used. The limiting magnitudes
(in good seeing and transparancy)
against a dark sky are fainter than V = 21.5 mag and V = 18.5 mag for
the Cassegrain and finder cameras, respectively and approximate
aperture photometry should be possible (in theory). Given that the
INT points well, the most important use of the finder is
the selection of guide stars for the Prime and Cassegrain autoguiders.
The Cassegrain TV camera is
used for acquisition and for guiding on light reflected from the
spectrograph slit jaws (section 
). It is possible to
archive a camera image on disc.