In general, the diopter of the left and right eyes differs among individuals. So the diopter correction rings on each of the left and right eyepieces should be adjusted to the diopter difference of the observer to minimize fatigue when observing.
Flow of diopter adjustments
Align the diopter ring with the engraved base line.
Please do the following.
①Using the 10X objective lense, rotate the focus knobs to bring the specimen in focus.
②Switch to the 40X objective lens and turn the fine focus knob to refocus on the sample.
③Switch to the 10X objective lens again, and adjust the focus by individually rotating only the diopter rings on the left and right eyepieces. Repeat ② and ③ twice to eliminate the visual differences between the left and right eyepieces.