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z
0
!-
;;
0::
Ul
(/)
Q)
0
Fig. 26
ID
Locking of the pre-focusing lever
Th
is
lever
Ci)
is
pr
o
vid ed
to p revent possible
con
tact between speci-
men and
object ive
as
w
ell
as to
simpl
ifv coarse
focusing The
l
e
~-er
1.s
locked
in the
d
irect
ion
of the ar rovv in Fig. 26. after
coarse
focus has
been
accom
pl
ished
.
T
h
i~
ls
conven ient
for liquid
apo hcati on
or
change o
f
specirflens
.
roo.
since
jt
preven
ls
fu
rther upw ard tr
avel
o
f
1l1e
stage by means o
l
the
coarse
ad
justment
k nobs
,
and
provides
a
l'
m
i
t1
ng
stop if
the
strtgfl is
lowered and
then
r aised
again
.
The
p
re-
focusing lever does not
restr
ict
fin.
e
fOG.Ut>lng.
*
Unlock
this
lever wh en not in
use.
m
Use of immersion objectives
l)
To
u
t
ili ze
the fu
ll numer
ical apert
u
re o
f
an
immersion
object ive [wi th
inscri pt ion
"
oil"
).
the
o h~ect
ive
and
spE,:c
im en
<!
re
lm nit3J
~eu
in an
i
m-
mersion oil
in a follow ing pro
ced
ure:
2
)
Focus on the
spec
imen
wit
h a
low
power
ob
jec
tive
.
3)
Pu.l
a
dro
p
o
f
immersion
oil
on
th
e
sJ:ec imen slide and the fron
t
lens
of the immersion
ob
jective.
4
}
T urn t
he nosepiece to br ing
t
he immersion ob
jecti
ve in to the
light
path
,
and focus
'lvit
h
th
e iine adj ustmen
t knobs.
*
Use of the pre -focusing lever facilitates steps 2) through 4}
above.
*
Care
should be taken to prevent oil bubbles from forming in the oil
film; if any, re-apply immersion oil, since these bubbles greatly
deteriorate
the lens performance.
*
Be careful not to stain other objectives with immersion 'oil, and
after use, carefully wip
e
off the immersion oil
on
the
objective,
etc.
completely
.
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