<s>
The	O
Asahi	B-Algorithm
Pentax	I-Algorithm
series	O
,	O
by	O
the	O
,	O
was	O
a	O
pivotal	O
development	O
in	O
modern	O
photography	O
.	O
</s>
<s>
They	O
were	O
the	O
earliest	O
Pentax	B-Application
cameras	I-Application
.	O
</s>
<s>
In	O
1957	O
,	O
the	O
Asahi	O
Optical	O
Company	O
(	O
later	O
"	O
Pentax	B-Application
"	O
)	O
introduced	O
the	O
Pentax	B-Application
,	O
a	O
35	O
mm	O
Single-lens	B-Algorithm
reflex	I-Algorithm
camera	I-Algorithm
(	O
SLR	B-Algorithm
)	O
camera	O
which	O
was	O
so	O
well	O
received	O
that	O
it	O
influenced	O
the	O
design	O
of	O
35mm	O
SLRs	B-Algorithm
worldwide	O
for	O
years	O
to	O
come	O
.	O
</s>
<s>
The	O
Pentax	B-Application
and	O
its	O
later	O
development	O
and	O
likewise	O
classic	O
1964	O
Pentax	B-Algorithm
Spotmatic	I-Algorithm
allowed	O
Asahi	O
Optical	O
Company	O
to	O
develop	O
into	O
a	O
photographic	O
multinational	O
company	O
,	O
eventually	O
leading	O
the	O
company	O
to	O
rename	O
itself	O
"	O
Pentax	B-Application
"	O
after	O
its	O
seminal	O
product	O
.	O
</s>
<s>
The	O
Asahi	B-Algorithm
Pentax	I-Algorithm
of	O
1957	O
featured	O
:	O
</s>
<s>
Earlier	O
35mm	O
SLRs	B-Algorithm
,	O
with	O
the	O
sole	O
exception	O
of	O
Exakta	O
's	O
left-handed	O
lever	O
,	O
had	O
knob	O
winders	O
;	O
</s>
<s>
Film	O
rewind	O
crank	O
,	O
likewise	O
a	O
first	O
for	O
35mm	O
SLRs	B-Algorithm
;	O
</s>
<s>
Instant	O
mirror	O
return	O
,	O
unique	O
to	O
the	O
Pentax	B-Application
and	O
its	O
immediate	O
predecessor	O
,	O
the	O
Asahiflex	B-Algorithm
IIb	I-Algorithm
;	O
</s>
<s>
Microprism	O
focusing	O
aids	O
on	O
the	O
focus	O
screen	O
,	O
unique	O
to	O
the	O
Pentax	B-Application
.	O
</s>
<s>
Moreover	O
,	O
the	O
Pentax	B-Application
placed	O
controls	O
in	O
locations	O
that	O
would	O
become	O
standard	O
on	O
35mm	O
SLRs	B-Algorithm
from	O
all	O
manufacturers	O
,	O
such	O
as	O
the	O
right-handed	O
rapid	O
wind	O
lever	O
,	O
the	O
bottom	O
right	O
mounted	O
rewind	O
release	O
.	O
</s>
<s>
It	O
also	O
had	O
a	O
film	O
speed	O
reminder	O
around	O
the	O
film	O
rewind	O
crank	O
,	O
a	O
location	O
that	O
remained	O
standard	O
until	O
the	O
dial	O
went	O
from	O
being	O
merely	O
a	O
reminder	O
to	O
the	O
photographer	O
to	O
actually	O
controlling	O
the	O
light	O
meter	O
built	O
into	O
later	O
SLRs	B-Algorithm
.	O
</s>
<s>
The	O
two	O
photographic	O
giants	O
,	O
Canon	O
and	O
Nikon	B-Algorithm
did	O
not	O
introduce	O
their	O
own	O
SLR	B-Algorithm
cameras	I-Algorithm
until	O
1959	O
with	O
the	O
Canonflex	B-Algorithm
and	O
the	O
F-series	B-Algorithm
respectively	O
.	O
</s>
<s>
By	O
contrast	O
,	O
the	O
Pentax	B-Application
offered	O
these	O
features	O
at	O
a	O
relatively	O
low	O
price	O
,	O
introducing	O
many	O
photographers	O
to	O
35mm	O
SLR	B-Algorithm
photography	O
.	O
</s>
<s>
The	O
Pentax	B-Application
became	O
so	O
dominant	O
that	O
the	O
42	B-Algorithm
mm	I-Algorithm
screw	I-Algorithm
lens	I-Algorithm
mount	I-Algorithm
used	O
on	O
the	O
Pentax	B-Application
and	O
Pentax	B-Algorithm
Spotmatic	I-Algorithm
become	O
known	O
as	O
the	O
"	O
Pentax	B-Algorithm
universal	I-Algorithm
screw	I-Algorithm
mount	I-Algorithm
"	O
although	O
it	O
had	O
actually	O
been	O
introduced	O
by	O
Praktica	O
in	O
1949	O
.	O
</s>
<s>
Later	O
cameras	O
required	O
more	O
lens-body	O
communication	O
to	O
implement	O
shutter	B-Algorithm
priority	I-Algorithm
exposure	O
,	O
program	O
auto	O
exposure	O
,	O
and	O
finally	O
,	O
autofocusing	O
,	O
and	O
different	O
manufacturers	O
used	O
different	O
interfaces	O
,	O
ending	O
the	O
era	O
of	O
interoperability	O
.	O
</s>
<s>
In	O
1975	O
Pentax	B-Application
introduced	O
the	O
K	B-Algorithm
mount	I-Algorithm
to	O
replace	O
the	O
42	B-Algorithm
mm	I-Algorithm
screw	I-Algorithm
lens	I-Algorithm
mount	I-Algorithm
used	O
so	O
successfully	O
until	O
then	O
.	O
</s>
