Olympus BHT-312 Gebruiksaanwijzing - Pagina 14

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1. Condenser Centration
1) S to p d ow n t he f ie ld i ri s diap hra gm w i t h
kn ur l e d r ing O by ro tati ng in t he d i r ec -
t i o n o f t h e a r r o w . ( F i g ' 1 4 )
2) Us e t he c o nden s er heig ht ad jus t m en t
k nob @ to m ov e the c o nden s er u P an d
do wn unt il an im ag e of th e fiel d d i a -
ph r a gm c an be s e en c le arl y in the e ye -
oi ec es . T he ro tatio n of the k n ob i n t h e
di r ec tion of th e a rr ow low ers the con -
F i e l d o f v i e w
l f t h e p o l y g o n a l i m a g e o f t h e i r i s
t h e f i e l d d i a p h r a g m i s c e n t e r e d .
o T he fiel d i ris diap hra gm c o ntro ts t h e d i am e t e r o f t h e r ay
b un d l e i m p i ni ng on t he sp eci -
m en s u rfac e and the refo re, b y s t o p pi n g do w n t h e
f i er d d i a p hr ag m u n t i l i t i s sl i g ht l y
la r g er th an the fi eld of v ie w, i t c an r e d uc e s t r ay
l i g ht , w h i ch i n t u r n i nc r ea se s i m ag e de f i -
ni ti o n a nd c on tra s t.
F i g . 14
denser.
F i e l d i r i s
di aphr agm
ffi+o
B r i n g t h e f i e l d i r i s d i a p h r a g m i m a g e i n t o
d en s er c ente rin g k nob s @ . (F ig. 1a )
t h e c e n t e r o f t h e f i e l d o f v i e w w i t h t h e t w o c o n -
4 ) W i d e n t h e d i a m e t e r o f t h e i r i s d i a p h r a g m p r o g r e s s i v e | y '
d i a p h r a g m b e c o m e s i n s c r i b e d i n t h e f i e | d i t m e a n s t h a t
( F i g . 1 5 )
F i e l d l r i s D i a P h r a g m
A pe r t ur e l ri s Di aPhr agm
o
r n o r d e r t o a c h i e v e o p t i m u m o b j e c t i v e
p e r f o r m a n c e , t h e o p e n i n g o f t h e a p e r t u r e r r s
d i a p h r a g m s h o u l d b e m a t c h e d t o t h e n u m e r i c a l
a p e r t u r e o f t h e o b j e c t i v e i n u s e ' l t i s
o f t e n p r e f e r a b l e , h o w e v e r , t o s t o p d o w n t h e a p e r t u r e
d i a p h r a g m s l i g h t l y m o r e t h a n i n -
d i c a t e d b y t h e o b j e c t i v e N . A . T h i s w i l l r e s u l t i n b e t t e r
i m a g e c o n t r a s t , i n c r e a s e d d e p t h o f
f o c u s a n d a f l a t t e r f i e l d .
A f t e r c o m p l e t i n g f o c u s a d j u s t m e n t , r e -
move one of the eyepieces from the ob-
s e r v a t i o n t u b e a n d l o o k i n t o t h e e m p t y
eyepiece tube. As You stoP down the
a p e r t u r e i r i s d i a p h r a g m , t h e i m a g e o f t h e
i r i s d i a p h r a g m c a n b e s e e n i n t h e o b j e c t -
i v e p u p i l . A d j u s t t h e o p e n i n g o f t h e
d i a p h r a g m t o m a t c h t h e N ' A . o f t h e o b -
j e c t i v e i n u s e . l f t h e s p e c i m e n i s l o w i n
contrast, it is recommended to stop down
l o 7 0 % - 8 O % o o f t h e o b j e c t i v e N . R '
( F i g '
1 6 )
O p e n i n g o f t h e
a p e r t u r e d i a P h r a g m
O b j e c t i v e e x i t P u P i l
1 2
F i g . 1 6