The information on this page refers to the 4-position objective turret for standard M27 thread lenses. There is also a single position turret for use with the M32 thread lens. Instructions for using that lens are in a separate document.
The 4-position Axio Examiner objective turret is more complicated than the nosepieces of most other microscopes. It's a manual turret but it doesn't simply freely rotate. Instead there is a knob on the front of the turret that must be rotated to the 'up' position (white mark points upwards) to allow the user to rotate the objectives using the metallic ring above the knob (see gloved fingers in the image below). Rotating the knob to the 'down' position (white mark points downwards) lowers the selected objective lens for imaging.
When the microscope is switched off the turret knob should be left parked with the 10x lens in the halfway position (white mark points to the side). This ensures that the objective lens is far enough away from the stage to avoid damage, and that the turret cannot be unintentionally rotated.
The previous user may have left a lens lowered in the down position, or they may have left the knob in the up orientation, in which case the turret can be accidentally revolved into a position between two objective lenses. In the former case it is important to raise the lens to avoid damage when you start up the machine or when you put a sample on the stage. In the latter case you will not be able to lower an objective lens until the turret is correctly rotated into position
