<s>
The	O
Olympus	B-Algorithm
Pen	I-Algorithm
F	I-Algorithm
,	O
Pen	O
FT	O
and	O
Pen	O
FV	O
are	O
very	O
similar	O
half-frame	O
35	O
mm	O
single-lens	B-Algorithm
reflex	I-Algorithm
(	O
SLR	B-Algorithm
)	O
cameras	O
with	O
interchangeable	O
lenses	O
produced	O
by	O
Olympus	O
of	O
Japan	O
between	O
1963-1966	O
(	O
Pen	O
F	O
)	O
,	O
1966-1972	O
(	O
Pen	O
FT	O
)	O
and	O
1967-1970	O
(	O
Pen	O
FV	O
)	O
.	O
</s>
<s>
The	O
smaller	O
image	O
format	O
also	O
allows	O
for	O
a	O
smaller	O
camera	O
and	O
lenses	O
,	O
making	O
the	O
Pen	O
F	O
system	O
one	O
of	O
the	O
smallest	O
SLR	B-Algorithm
systems	O
ever	O
made	O
;	O
the	O
Pentax	B-Algorithm
Auto	I-Algorithm
110	I-Algorithm
was	O
smaller	O
,	O
but	O
with	O
a	O
much	O
more	O
limited	O
range	O
of	O
lenses	O
and	O
accessories	O
,	O
and	O
smaller	O
110	O
film	O
.	O
</s>
<s>
These	O
cameras	O
are	O
somewhat	O
exceptional	O
since	O
they	O
used	O
a	O
rotary	O
focal-plane	O
shutter	O
,	O
rather	O
than	O
the	O
two-curtain	O
focal-plane	O
shutter	O
commonly	O
used	O
in	O
other	O
SLRs	B-Algorithm
at	O
that	O
time	O
.	O
</s>
