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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) . This allows 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.
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