Bestscope International Limited
BS-2090
4-3 the viewing tube
4-3-1
Adjusting the diopter
（
fig.21
）
1. Look into the right ocular by your right eye,
then revolving the coarse focus knob to focus
on the specimen.
2. Then use your left eye to look into the left
ocular. If the image is not sharp, just use the
diopter adjustment ring
①
to adjust please.
★
There are ±5 diopter in the adjustment
ring. The number which the reticle on the
eyepiece holder pointed is your eye’s diopter
graduation.
4-3-2 Adjusting the interpupillar distance
（
fig.22
）
When observing with two eyes, hold on the left
and right prism holder, turn around the axis,
adjusting the interpupillar distance until the left and
right fields of view coincide completely.
★
The reticle on the interpupillar distance
indicator
③
,
pointed by the spot “.”
②
on the
eyepiece holder, shows the scale of the
interpupillar distance.
（
fig.21
）
The range of the interpupillar distance
：
48
～
75mm
。
Figure 21
Figure 22
2
3
