<s>
The	O
hot	O
shoe	O
is	O
a	O
development	O
of	O
the	O
standardised	O
"	O
accessory	O
shoe	O
"	O
,	O
with	O
no	O
flash	O
contacts	O
,	O
formerly	O
fitted	O
to	O
cameras	O
to	O
hold	O
accessories	O
such	O
as	O
a	O
rangefinder	B-Algorithm
,	O
or	O
flash	O
connected	O
by	O
a	O
cable	O
.	O
</s>
<s>
Measured	O
on	O
a	O
Nikon	B-Algorithm
D3400	I-Algorithm
,	O
the	O
internal	O
dimensions	O
are	O
18.7mm	O
x	O
18.0mm	O
x	O
2.05mm	O
whereas	O
the	O
external	O
dimensions	O
are	O
20.7mm	O
x	O
18mm	O
x	O
5.1mm	O
.	O
</s>
<s>
Before	O
the	O
1970s	O
,	O
many	O
cameras	O
had	O
an	O
"	O
accessory	O
shoe	O
"	O
intended	O
to	O
hold	O
accessories	O
including	O
flashes	O
that	O
connected	O
electrically	O
via	O
a	O
cable	O
,	O
external	O
light	O
meters	O
,	O
special	O
viewfinders	O
,	O
or	O
rangefinders	B-Algorithm
.	O
</s>
<s>
Canon	O
,	O
Nikon	B-Algorithm
,	O
Olympus	O
,	O
and	O
Pentax	B-Application
use	O
the	O
standard	O
ISO	O
hot	O
shoe	O
with	O
various	O
proprietary	O
electronic	O
extensions	O
.	O
</s>
<s>
In	O
1988	O
Minolta	O
switched	O
to	O
use	O
a	O
4-pin	O
proprietary	B-Algorithm
slide-on	I-Algorithm
auto-lock	I-Algorithm
"	I-Algorithm
iISO	I-Algorithm
"	I-Algorithm
connector	I-Algorithm
.	O
</s>
<s>
Konica	O
Minolta	O
and	O
Sony	B-Algorithm
Alpha	I-Algorithm
digital	O
SLR	O
cameras	O
are	O
based	O
on	O
Minolta	O
designs	O
and	O
used	O
the	O
same	O
connector	O
,	O
officially	O
named	O
Auto-lock	B-Algorithm
Accessory	I-Algorithm
Shoe	I-Algorithm
,	O
as	O
well	O
up	O
to	O
2012	O
.	O
</s>
<s>
Since	O
the	O
electrical	O
protocol	O
remained	O
mostly	O
compatible	O
,	O
TTL	O
and	O
non-TTL	O
adapters	O
exist	O
to	O
adapt	O
ISO-based	O
flashes	O
to	O
iISO	B-Algorithm
hotshoes	I-Algorithm
and	O
vice	O
versa	O
.	O
</s>
<s>
Sony	O
also	O
used	O
a	O
variety	O
of	O
other	O
proprietary	O
hotshoes	O
for	O
other	O
digital	O
cameras	O
,	O
including	O
the	O
ISO-based	O
6-pin	O
Cyber-shot	B-Device
hotshoe	O
,	O
the	O
16-pin	O
Active	O
Interface	O
Shoe	O
(	O
AIS	O
)	O
and	O
the	O
ISO-based	O
16-pin	O
Intelligent	O
Accessory	O
Shoe	O
(	O
IAS	O
)	O
.	O
</s>
<s>
Some	O
of	O
their	O
NEX	B-Algorithm
cameras	O
used	O
a	O
proprietary	O
Smart	O
Accessory	O
Terminal	O
(	O
versions	O
1	O
and	O
2	O
)	O
.	O
</s>
<s>
In	O
September	O
2012	O
,	O
Sony	O
announced	O
a	O
new	O
ISO-based	O
21+3	O
pin	O
Multi	B-Algorithm
Interface	I-Algorithm
Shoe	I-Algorithm
for	O
use	O
with	O
their	O
future	O
digital	O
cameras	O
of	O
the	O
Alpha	O
,	O
NEX	B-Algorithm
,	O
Handycam	B-Algorithm
,	O
NXCAM	O
and	O
Cyber-shot	B-Device
series	O
.	O
</s>
<s>
This	O
quick-lock	O
hotshoe	O
is	O
mechanically	O
and	O
electrically	O
compatible	O
with	O
a	O
standard	O
2-pin	O
ISO-518	O
hotshoe	O
,	O
but	O
electrically	O
compatible	O
with	O
the	O
previous	O
Auto-lock	B-Algorithm
Accessory	I-Algorithm
Shoe	I-Algorithm
with	O
extensions	O
,	O
so	O
that	O
passive	O
adapters	O
ADP-AMA	O
and	O
ADP-MAA	O
allow	O
the	O
use	O
of	O
digital-ready	O
iISO	B-Algorithm
flashes	O
on	O
new	O
cameras	O
and	O
some	O
new	O
Multi	B-Algorithm
Interface	I-Algorithm
Shoe	I-Algorithm
equipment	O
on	O
older	O
cameras	O
,	O
while	O
providing	O
compatibility	O
with	O
standard	O
ISO-based	O
equipment	O
as	O
well	O
.	O
</s>
<s>
iISO	B-Algorithm
hotshoe	I-Algorithm
contacts	O
are	O
only	O
protected	O
up	O
to	O
ca	O
.	O
</s>
<s>
They	O
use	O
either	O
transformers	B-Algorithm
or	O
opto-couplers	O
to	O
transfer	O
a	O
safe	O
trigger	O
impulse	O
from	O
the	O
camera	O
to	O
the	O
flash	O
.	O
</s>
<s>
There	O
is	O
still	O
a	O
need	O
for	O
accessory	O
shoes	O
without	O
electrical	O
function	O
(	O
cold	B-Algorithm
shoes	I-Algorithm
)	O
.	O
</s>
<s>
For	O
instance	O
a	O
stereo	O
microphone	B-Application
or	O
electronic	O
viewfinder	O
can	O
be	O
used	O
in	O
the	O
Olympus	B-Algorithm
XZ-1	I-Algorithm
camera	O
's	O
hot	O
shoe	O
.	O
</s>
