The UHRF aquisition TV (Pulnix CCD) is located slightly off axis back, towards the coudé 5 mirror. Since the Pulnix camera does not maintain focus with changing zoom, the zoom should be fixed for the night or if it is necessary to zoom out (for target aquisition) then the zoom should be returned to the same value. Since the zoom is not encoded the following technique can be used to return to the original zoom value. When zoom and focus are first established, a fiducial mark should be placed in the centre of the square entrance hole on the slicer dekker. Bringing the hole back to this fiducial returns the original zoom. Select ARC THAR and use its illumination to locate the slicer entrance aperture.