<s>
The	O
Pentax	B-Algorithm
ME	I-Algorithm
F	I-Algorithm
was	O
an	O
amateur	O
level	O
,	O
interchangeable	O
lens	O
,	O
35	O
mm	O
film	O
,	O
single-lens	B-Algorithm
reflex	I-Algorithm
(	O
SLR	B-Algorithm
)	O
camera	O
.	O
</s>
<s>
It	O
was	O
manufactured	O
by	O
Asahi	B-Application
Optical	I-Application
Co.	I-Application
,	I-Application
Ltd	I-Application
.	I-Application
of	O
Japan	O
from	O
November	O
1981	O
to	O
1984	O
.	O
</s>
<s>
The	O
ME	O
F	O
was	O
a	O
heavily	O
modified	O
version	O
of	O
the	O
Pentax	B-Algorithm
ME-Super	I-Algorithm
,	O
and	O
a	O
member	O
of	O
the	O
Pentax	B-Application
M-series	O
family	O
of	O
SLRs	B-Algorithm
(	O
see	O
List	O
of	O
Pentax	B-Application
products	O
)	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
mass-produced	O
SLR	B-Algorithm
camera	I-Algorithm
to	O
come	O
with	O
an	O
autofocus	O
system	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
autofocus	O
(	O
AF	O
)	O
35mm	O
SLR	B-Algorithm
camera	I-Algorithm
to	O
reach	O
production	O
.	O
</s>
<s>
Although	O
it	O
autofocused	O
poorly	O
and	O
was	O
a	O
commercial	O
failure	O
,	O
the	O
pioneering	O
ME	O
F	O
was	O
a	O
major	O
milestone	O
in	O
the	O
history	O
of	O
camera	O
technology	O
that	O
pointed	O
the	O
way	O
to	O
all	O
present	O
day	O
AF	O
SLRs	B-Algorithm
.	O
</s>
<s>
Note	O
that	O
the	O
ME	O
F	O
was	O
not	O
the	O
first	O
AF	O
still	O
camera	O
,	O
or	O
even	O
the	O
first	O
AF	O
SLR	B-Algorithm
camera	I-Algorithm
,	O
to	O
reach	O
consumers	O
.	O
</s>
<s>
Those	O
honors	O
go	O
to	O
the	O
Konica	B-Algorithm
C35	I-Algorithm
AF	I-Algorithm
35mm	O
point-and-shoot	O
,	O
with	O
an	O
electronic	O
rangefinder	B-Algorithm
system	O
,	O
of	O
1977	O
and	O
the	O
Polaroid	B-Algorithm
SX-70	I-Algorithm
Sonar	I-Algorithm
instant	O
film	O
SLR	B-Algorithm
,	O
with	O
a	O
sonar	B-Application
echo-ranging	O
system	O
,	O
of	O
1978	O
,	O
respectively	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
trivial	O
examples	O
of	O
the	O
fixed	O
lenses	O
on	O
the	O
AF	O
cameras	O
mentioned	O
above	O
,	O
interchangeable	O
35mm	O
SLR	B-Algorithm
AF	O
lenses	O
had	O
come	O
out	O
just	O
before	O
it	O
from	O
Canon	O
,	O
Ricoh	O
and	O
Chinon	O
with	O
self-contained	O
non-TTL	O
AF	O
sensors	O
,	O
computer	O
and	O
motor	O
.	O
</s>
<s>
The	O
ME	O
F	O
,	O
a	O
heavily	O
modified	O
version	O
of	O
the	O
Pentax	B-Algorithm
ME	I-Algorithm
Super	I-Algorithm
of	O
1979	O
,	O
was	O
a	O
member	O
of	O
the	O
Pentax	B-Application
M-series	O
SLRs	B-Algorithm
,	O
along	O
with	O
the	O
Pentax	B-Algorithm
ME	I-Algorithm
(	O
1976	O
)	O
,	O
MX	B-Algorithm
(	O
1977	O
)	O
,	O
MV	O
(	O
1979	O
)	O
,	O
MV-1	O
(	O
1980	O
)	O
,	O
and	O
MG	B-Algorithm
(	O
1982	O
)	O
.	O
</s>
<s>
They	O
all	O
used	O
the	O
same	O
basic	O
ultra-compact	O
aluminium	O
alloy	O
chassis	O
(	O
except	O
for	O
the	O
MX	B-Algorithm
,	O
which	O
had	O
a	O
different	O
chassis	O
but	O
used	O
similar	O
styling	O
)	O
.	O
</s>
<s>
The	O
M-series	O
remain	O
among	O
the	O
smallest	O
and	O
lightest	O
full-frame	O
35mm	O
film	O
SLRs	B-Algorithm
ever	O
made	O
.	O
</s>
<s>
The	O
ME	O
F	O
with	O
SMC	O
Pentax	B-Application
AF	O
35mm-70mm	O
f/2.8	O
Zoom	O
Lens	O
autofocus	O
lens	O
(	O
required	O
for	O
autofocus	O
operation	O
;	O
see	O
below	O
)	O
had	O
a	O
list	O
price	O
of	O
$994	O
.	O
</s>
<s>
Note	O
that	O
SLRs	B-Algorithm
usually	O
sold	O
for	O
30	O
to	O
40	O
percent	O
below	O
list	O
price	O
.	O
</s>
<s>
Although	O
the	O
ME	O
F	O
was	O
an	O
interchangeable	O
lens	O
camera	O
(	O
the	O
photographer	O
could	O
remove	O
and	O
exchange	O
its	O
lens	O
for	O
another	O
)	O
,	O
its	O
AF	O
function	O
required	O
the	O
unique	O
SMC	O
Pentax	B-Application
AF	O
35	O
mm	O
–	O
70	O
mm	O
f/2.8	O
Zoom	O
Lens	O
autofocus	O
lens	O
using	O
a	O
special	O
Pentax	B-Application
K-F	O
lens	O
mount	O
.	O
</s>
<s>
Unlike	O
all	O
later	O
Pentax	B-Application
AF	O
SLRs	B-Algorithm
,	O
the	O
ME	O
F	O
did	O
not	O
have	O
the	O
focusing	O
drive	O
motor	O
and	O
keying	O
shaft	O
built	O
into	O
the	O
camera	O
body	O
.	O
</s>
<s>
The	O
Pentax	B-Algorithm
K-F	I-Algorithm
mount	I-Algorithm
added	O
five	O
electrical	O
contact	O
pins	O
protruding	O
through	O
the	O
lens	O
mount	O
flange	O
at	O
the	O
5	O
o'clock	O
position	O
(	O
when	O
viewing	O
the	O
ME	O
F	O
body	O
from	O
the	O
front	O
)	O
to	O
the	O
original	O
Pentax	B-Algorithm
K	I-Algorithm
mount	I-Algorithm
(	O
introduced	O
1975	O
)	O
to	O
pass	O
focus	O
control	O
information	O
between	O
the	O
camera	O
and	O
the	O
lens	O
.	O
</s>
<s>
The	O
Pentax	B-Application
K-AF	O
and	O
K-AF2	O
autofocus	O
lens	O
mounts	O
(	O
introduced	O
1987	O
and	O
1991	O
,	O
respectively	O
)	O
have	O
contacts	O
of	O
different	O
number	O
,	O
position	O
and	O
function	O
,	O
and	O
therefore	O
the	O
35mm-70mm	O
AF	O
Zoom	O
cannot	O
autofocus	O
on	O
any	O
other	O
Pentax	B-Application
SLR	B-Algorithm
.	O
</s>
<s>
Almost	O
all	O
other	O
Pentax	B-Algorithm
K	I-Algorithm
mount	I-Algorithm
bayonet	O
lenses	O
will	O
function	O
properly	O
under	O
manual	O
focusing	O
,	O
with	O
the	O
AF	O
system	O
providing	O
focus	O
indication	O
–	O
Asahi	O
Optical	O
called	O
this	O
TTL	O
Electronic	O
Focus	O
.	O
</s>
<s>
This	O
includes	O
lenses	O
with	O
the	O
Pentax	B-Application
K-A	O
mount	O
(	O
introduced	O
1983	O
)	O
and	O
the	O
K-AF/AF2	O
mounts	O
.	O
</s>
<s>
However	O
,	O
the	O
newest	O
SMC-Pentax	O
FA	O
J	O
(	O
1997	O
)	O
and	O
SMC-Pentax	O
DA	O
(	O
2004	O
)	O
types	O
,	O
lacking	O
an	O
aperture	O
control	O
ring	O
,	O
have	O
severely	O
restricted	O
functionality	O
.	O
</s>
<s>
There	O
were	O
over	O
thirty	O
contemporary	O
manual	O
focus	O
Asahi	O
Optical	O
made	O
lenses	O
of	O
the	O
SMC	O
Pentax-M	O
and	O
SMC	O
Pentax-A	O
types	O
.	O
</s>
<s>
In	O
the	O
module	O
,	O
beam	O
splitter	O
mirrors	O
sent	O
the	O
light	O
to	O
fall	O
on	O
a	O
two	O
row	O
,	O
segmented	O
,	O
linear	O
metal	B-Architecture
oxide	I-Architecture
semiconductor	I-Architecture
(	O
MOS	O
)	O
silicon	O
sensor	O
.	O
</s>
<s>
Modern	O
AF	O
SLRs	B-Algorithm
use	O
similar	O
,	O
though	O
much	O
evolved	O
,	O
AF	O
hardware	O
;	O
however	O
,	O
their	O
AF	O
software	O
no	O
longer	O
analyze	O
contrast	O
.	O
</s>
<s>
After	O
lightly	O
pressing	O
the	O
shutter	O
button	O
,	O
the	O
photographer	O
would	O
turn	O
Pentax	B-Application
brand	O
manual	O
focus	O
lenses	O
in	O
the	O
direction	O
of	O
whichever	O
red	O
arrow	O
LED	O
lit	O
until	O
the	O
green	O
LED	O
lit	O
to	O
indicate	O
sharp	O
focus	O
.	O
</s>
<s>
Note	O
that	O
many	O
independent	O
manufacturer	O
K	B-Algorithm
mount	I-Algorithm
lenses	O
focus	O
by	O
turning	O
in	O
the	O
opposite	O
direction	O
of	O
Asahi	O
Optical	O
made	O
lenses	O
and	O
that	O
the	O
focus	O
direction	O
LEDs	O
will	O
point	O
the	O
"	O
wrong	O
"	O
way	O
for	O
them	O
.	O
</s>
<s>
Except	O
for	O
the	O
AF	O
system	O
,	O
the	O
ME	O
F	O
was	O
very	O
similar	O
to	O
the	O
ME	O
Super	O
:	O
an	O
almost	O
all	O
metal	O
,	O
electromechanically	O
(	O
much	O
electronics	O
,	O
but	O
many	O
springs	O
,	O
gears	O
and	O
levers	O
)	O
controlled	O
manual	O
focus	O
SLR	B-Algorithm
with	O
manual	O
exposure	O
control	O
or	O
aperture	B-Algorithm
priority	I-Algorithm
autoexposure	O
.	O
</s>
<s>
In	O
aperture	B-Algorithm
priority	I-Algorithm
mode	I-Algorithm
,	O
a	O
steadily	O
lit	O
LED	O
indicated	O
the	O
shutter	O
speed	O
automatically	O
set	O
by	O
the	O
electronic	O
microprocessor	O
in	O
response	O
to	O
the	O
light	O
reaching	O
the	O
built-in	O
,	O
open	O
aperture	O
,	O
through-the-lens	O
(	O
TTL	O
)	O
,	O
centre-weighted	O
gallium	O
arsenide	O
phosphide	O
photodiode	O
(	O
GPD	O
)	O
light	O
meter	O
and	O
the	O
set	O
lens	O
aperture	O
.	O
</s>
<s>
Unlike	O
most	O
other	O
SLRs	B-Algorithm
of	O
the	O
era	O
,	O
the	O
ME	O
F	O
used	O
two	O
push	O
buttons	O
to	O
increase	O
or	O
decrease	O
shutter	O
speeds	O
instead	O
of	O
the	O
traditional	O
dial	O
and	O
this	O
LED	O
scale	O
is	O
the	O
only	O
display	O
of	O
the	O
set	O
shutter	O
speed	O
.	O
</s>
<s>
What	O
appeared	O
to	O
be	O
a	O
shutter	O
speed	O
dial	O
on	O
autoexposure	O
M-series	O
SLRs	B-Algorithm
was	O
actually	O
the	O
exposure	O
mode	O
dial	O
:	O
AUTO	O
meant	O
aperture	B-Algorithm
priority	I-Algorithm
and	O
M	O
was	O
for	O
manual	O
.	O
</s>
<s>
The	O
viewfinder	O
also	O
had	O
a	O
fixed	O
focusing	O
screen	O
with	O
Asahi	O
Optical	O
's	O
standard	O
split	O
image	O
rangefinder	B-Algorithm
and	O
microprism	O
collar	O
manual	O
focusing	O
aids	O
.	O
</s>
<s>
The	O
split	O
image	O
rangefinder	B-Algorithm
was	O
a	O
good	O
indication	O
of	O
the	O
width	O
of	O
the	O
AF	O
sensor	O
field	O
of	O
view	O
.	O
</s>
<s>
Major	O
accessories	O
for	O
the	O
ME	O
F	O
included	O
the	O
Pentax	B-Application
Winder	O
ME	O
II	O
autowinder	O
(	O
automatic	O
film	O
advance	O
up	O
to	O
2	O
frames	O
per	O
second	O
)	O
,	O
Pentax	B-Application
Dial	O
Data	O
ME	O
databack	O
(	O
date	O
stamping	O
on	O
the	O
film	O
)	O
,	O
and	O
the	O
Pentax	B-Application
AF	O
200S	O
(	O
guide	O
number	O
66/20	O
(	O
feet/meters	O
)	O
at	O
ASA	O
100	O
)	O
and	O
AF	O
280T	O
(	O
guide	O
number	O
90/28	O
(	O
feet/meters	O
)	O
at	O
ASA	O
100	O
)	O
electronic	O
flashes	O
.	O
</s>
<s>
The	O
1970s	O
and	O
1980s	O
were	O
an	O
era	O
of	O
intense	O
competition	O
between	O
the	O
major	O
SLR	B-Algorithm
brands	O
:	O
Pentax	B-Application
,	O
Nikon	B-Algorithm
,	O
Canon	O
,	O
Minolta	O
and	O
Olympus	O
.	O
</s>
<s>
The	O
introduction	O
of	O
integrated	O
circuit	O
(	O
IC	O
)	O
microprocessors	O
made	O
it	O
easy	O
for	O
SLRs	B-Algorithm
to	O
provide	O
convenience	O
features	O
like	O
electronically	O
timed	O
shutters	O
,	O
electronic	O
autoexposure	O
,	O
electronic	O
information	O
displays	O
(	O
using	O
LEDs	O
or	O
LCDs	B-Device
)	O
and	O
use	O
electronic	O
computer	O
calculated	O
zoom	O
lenses	O
.	O
</s>
<s>
The	O
industry	O
was	O
trying	O
to	O
expand	O
out	O
from	O
the	O
saturated	O
high-end	O
professional	O
and	O
advanced	O
amateur	O
market	O
and	O
appeal	O
to	O
the	O
large	O
mass	O
of	O
low-end	O
amateur	O
photographers	O
itching	O
to	O
move	O
up	O
from	O
compact	O
automatic	O
leaf	O
shutter	O
rangefinder	B-Algorithm
(	O
RF	O
)	O
cameras	O
to	O
the	O
more	O
versatile	O
and	O
glamorous	O
SLR	B-Algorithm
but	O
were	O
intimidated	O
by	O
the	O
need	O
to	O
learn	O
all	O
the	O
gritty	O
details	O
of	O
operating	O
a	O
traditional	O
SLR	B-Algorithm
.	O
</s>
<s>
The	O
Asahi	O
Pentax	B-Application
Electro	O
Spotmatic	O
(	O
Honeywell	O
Pentax	B-Application
Spotmatic	O
ES	O
in	O
the	O
USA	O
)	O
of	O
1971	O
was	O
the	O
first	O
35mm	O
SLR	B-Algorithm
with	O
electronic	O
aperture	B-Algorithm
priority	I-Algorithm
autoexposure	O
and	O
the	O
Pentax	B-Algorithm
ME	I-Algorithm
was	O
the	O
first	O
electronic	O
autoexposure-only	O
35mm	O
SLR	B-Algorithm
.	O
</s>
<s>
By	O
1981	O
,	O
almost	O
every	O
part	O
of	O
the	O
classic	O
mount	O
lens/load	O
film/compose/focus/meter/f-stop/shutter	O
speed/shoot/wind	O
sequence	O
of	O
SLR	B-Algorithm
operation	O
could	O
be	O
automated	O
–	O
although	O
no	O
single	O
production	O
SLR	B-Algorithm
or	O
even	O
single	O
brand	O
of	O
SLRs	B-Algorithm
possessed	O
all	O
existing	O
features	O
.	O
</s>
<s>
It	O
and	O
the	O
other	O
first	O
generation	O
autofocus	O
or	O
focus	O
indication	O
35mm	O
SLRs	B-Algorithm
(	O
such	O
as	O
the	O
Canon	B-Algorithm
AL-1	I-Algorithm
of	O
1982	O
,	O
the	O
1983	O
Olympus	O
OM-30	O
(	O
called	O
the	O
Olympus	O
OM-F	O
in	O
the	O
USA	O
)	O
,	O
or	O
the	O
Nikon	B-Algorithm
F3	I-Algorithm
AF	I-Algorithm
,	O
also	O
of	O
1983	O
)	O
were	O
the	O
beginning	O
of	O
a	O
dominant	O
breed	O
of	O
camera	O
.	O
</s>
<s>
Asahi	O
Optical	O
turned	O
away	O
from	O
AF	O
and	O
came	O
out	O
with	O
the	O
Pentax	B-Algorithm
Super-A	I-Algorithm
(	O
Super	O
Program	O
in	O
the	O
USA	O
)	O
,	O
a	O
less	O
radical	O
SLR	B-Algorithm
also	O
built	O
upon	O
the	O
M-series	O
chassis	O
,	O
but	O
offering	O
the	O
much	O
more	O
mainstream	O
features	O
of	O
programmed	O
autoexposure	O
and	O
TTL	O
autoflash	O
,	O
in	O
mid-1983	O
.	O
</s>
<s>
The	O
ME	O
F	O
was	O
quietly	O
dropped	O
from	O
the	O
Pentax	B-Application
lineup	O
in	O
1984	O
.	O
</s>
<s>
It	O
would	O
not	O
be	O
until	O
the	O
introduction	O
of	O
the	O
landmark	O
Minolta	B-Algorithm
Maxxum	I-Algorithm
7000	I-Algorithm
(	O
Alpha	O
7000	O
in	O
Japan	O
)	O
in	O
1985	O
,	O
with	O
its	O
superior	O
and	O
better	O
integrated	O
phase	O
comparison	O
AF	O
system	O
and	O
far	O
wider	O
lens	O
and	O
accessory	O
selection	O
,	O
that	O
autofocusing	O
captured	O
the	O
35mm	O
SLR	B-Algorithm
buying	O
public	O
's	O
imagination	O
and	O
the	O
AF	O
SLR	B-Algorithm
camera	I-Algorithm
revolution	O
truly	O
began	O
.	O
</s>
<s>
Asahi	O
Optical	O
's	O
second	O
AF	O
SLR	B-Algorithm
,	O
the	O
Pentax	B-Algorithm
SFX	I-Algorithm
(	O
SF1	O
in	O
the	O
USA	O
)	O
,	O
introduced	O
in	O
1987	O
,	O
owed	O
its	O
configuration	O
more	O
to	O
the	O
Maxxum	O
than	O
to	O
the	O
ME	O
F	O
;	O
one	O
that	O
modern	O
Pentax	B-Application
(	O
and	O
Samsung	B-Application
)	O
digital	O
SLRs	B-Algorithm
continue	O
to	O
use	O
today	O
.	O
</s>
