<s>
A	O
reflex	B-Algorithm
finder	I-Algorithm
is	O
a	O
viewfinder	O
system	O
with	O
a	O
mirror	O
placed	O
behind	O
a	O
lens	O
.	O
</s>
<s>
The	O
image	O
formed	O
on	O
this	O
ground	O
glass	O
can	O
be	O
observed	O
directly	O
,	O
giving	O
a	O
waist-level	O
reflex	B-Algorithm
finder	I-Algorithm
,	O
or	O
through	O
a	O
redressing	O
optical	O
device	O
(	O
set	O
of	O
mirrors	O
or	O
prism	O
)	O
for	O
eye-level	O
viewing	O
,	O
giving	O
an	O
eye-level	O
reflex	B-Algorithm
finder	I-Algorithm
.	O
</s>
<s>
With	O
a	O
reflex	B-Algorithm
finder	I-Algorithm
,	O
you	O
can	O
focus	O
the	O
image	O
on	O
the	O
ground	O
glass	O
and	O
frame	O
your	O
picture	O
at	O
the	O
same	O
time	O
.	O
</s>
<s>
It	O
is	O
common	O
to	O
find	O
a	O
device	O
on	O
the	O
center	O
of	O
the	O
ground	O
glass	O
to	O
help	O
precise	O
focusing	O
,	O
for	O
example	O
a	O
split-image	O
or	O
a	O
microprism	B-Architecture
device	O
.	O
</s>
<s>
Reflex	B-Algorithm
finders	I-Algorithm
are	O
found	O
in	O
:	O
</s>
