<s>
The	O
Leica	O
M4	O
is	O
a	O
35	O
mm	O
rangefinder	B-Algorithm
camera	I-Algorithm
produced	O
by	O
Ernst	O
Leitz	O
GmbH	O
.	O
</s>
<s>
The	O
M4	O
started	O
production	O
in	O
November	O
1966	O
,	O
as	O
the	O
direct	O
successor	O
of	O
the	O
M3	B-Algorithm
and	O
M2	B-Algorithm
,	O
featuring	O
framelines	O
for	O
35mm	O
,	O
50mm	O
,	O
90mm	O
and	O
135mm	O
lenses	O
in	O
a	O
0.72	O
magnification	O
viewfinder	O
.	O
</s>
<s>
It	O
has	O
the	O
frame	O
counter	O
of	O
the	O
M3	B-Algorithm
,	O
with	O
automatic	O
reset	O
after	O
reloading	O
.	O
</s>
<s>
The	O
M4	O
was	O
the	O
last	O
Leica	O
rangefinder	B-Algorithm
of	O
this	O
era	O
to	O
be	O
predominantly	O
hand-built	O
.	O
</s>
<s>
A	O
scientific	O
version	O
without	O
a	O
viewfinder	O
was	O
made	O
as	O
the	O
Leica	O
MDa	O
(	O
similar	O
to	O
the	O
Leica	B-Algorithm
M1	I-Algorithm
)	O
.	O
</s>
<s>
Its	O
successor	O
,	O
the	O
M5	B-Algorithm
had	O
been	O
introduced	O
in	O
1971	O
.	O
</s>
<s>
However	O
,	O
the	O
relatively	O
bulky	O
and	O
expensive	O
M5	B-Algorithm
met	O
with	O
a	O
cool	O
reception	O
,	O
and	O
sales	O
did	O
not	O
live	O
up	O
to	O
Leica	O
's	O
expectations	O
.	O
</s>
<s>
The	O
M4-2	O
added	O
a	O
hot	B-Algorithm
shoe	I-Algorithm
and	O
motor	B-Algorithm
drive	I-Algorithm
compatibility	O
as	O
standard	O
,	O
but	O
removed	O
the	O
self-timer	O
.	O
</s>
<s>
The	O
range	O
continued	O
with	O
the	O
Leica	B-Algorithm
M6	I-Algorithm
in	O
1984	O
,	O
which	O
was	O
essentially	O
an	O
M4-P	O
with	O
through-the-lens	O
(	O
TTL	O
)	O
light	O
metering	O
.	O
</s>
