f.3Bio

for low power:
1.you can use the coarse adjustment knob
2.you don't need table lamp

for high power
1.you should use the fine adjustment knob
because the distance between the objective and rhe slide is very small.
it is easy to break the slide and the objective if the coarse adjustment knob is used
2.you need a table lamp
because the distance between the objective and rhe slide is very small.
little light can "shine" on the slide and the image will be very dim