Steps

• 1. Set object lens to x4 and place your stage micrometre on the microscope stage and line the graticuleup with it (line the 0’s up)
• 2. Calculate how many divisions of the stage micrometre the eyepiece graticule takes up; 100eyepiece divisions = 25stage divisions; 1SD = 0.1mm, 25 SD = 2.5mm = 100ED
• 3. If we want to know how many mm the eyepiece graticule measures, we need to find out the length of one (1ED = 2.5/100 = 0.025mm)
• 4. Convert it to μm as it is more useful when measuring cells (0.025mm x 1000 = 25μm); this is our final conversion value for our eyepiece graticule at x4 lens