<s>
Leica	B-Algorithm
R4	I-Algorithm
,	O
R5	O
,	O
R6	O
,	O
R7	O
were	O
35mm	O
SLR	B-Algorithm
cameras	I-Algorithm
manufactured	O
by	O
Leica	O
between	O
1980	O
and	O
1997	O
and	O
belonged	O
to	O
the	O
manual	O
focusing	O
R-System	O
,	O
which	O
was	O
offered	O
from	O
1965	O
to	O
2009	O
.	O
</s>
<s>
Following	O
the	O
success	O
of	O
the	O
Leica	B-Algorithm
R3	I-Algorithm
the	O
company	O
,	O
in	O
continuing	O
cooperation	O
with	O
Minolta	O
,	O
produced	O
the	O
R4-R7	O
series	O
all	O
based	O
on	O
the	O
same	O
chassis	O
.	O
</s>
<s>
Based	O
on	O
Minolta	B-Algorithm
XD-7	I-Algorithm
but	O
with	O
Leica	O
developed	O
exposure	O
metering	O
,	O
mirror	O
box	O
,	O
and	O
newly	O
designed	O
body	O
,	O
the	O
R4	O
followed	O
the	O
trend	O
setting	O
Olympus	B-Algorithm
OM-1	I-Algorithm
and	O
was	O
much	O
smaller	O
and	O
lighter	O
than	O
all	O
earlier	O
Leica	O
SLR	B-Algorithm
cameras	I-Algorithm
.	O
</s>
<s>
In	O
comparison	O
to	O
the	O
earlier	O
models	O
of	O
the	O
R4	O
,	O
it	O
's	O
upgraded	O
successor	O
R5	O
proved	O
to	O
be	O
a	O
very	O
reliable	O
and	O
well-received	O
SLR	B-Algorithm
camera	I-Algorithm
,	O
although	O
manual	O
focusing	O
was	O
already	O
considered	O
obsolete	O
by	O
the	O
time	O
it	O
appeared	O
,	O
as	O
most	O
other	O
SLR	B-Algorithm
manufacturers	O
switched	O
to	O
new	O
developed	O
auto	O
focus	O
systems	O
during	O
the	O
late	O
1980	O
's	O
.	O
</s>
