Further…
nCheck the condenser. We shall not go into the details of adjusting the condenser and centering it. Hopefully these arrangements will not be disturbed. (These adjustments are critical in advanced microscopy).
nFor our purpose : Low power = low condenser,
n High power = high condenser.
nNow peep through the eyepieces. Adjust your eye positions until you see a single circle of light when both eyes are open. It is very tempting to close one eye to escape this little exercise, but these bad habits are hard to kill!
nAdjust the distance between the eyepieces until you succeed with this.
nCheck the iris diaphragm if the light is very dim.