<s>
The	O
Sigma	O
30mm	O
1.4	O
EX	O
DC	O
HSM	O
is	O
a	O
wide-aperture	O
photographic	O
lens	O
made	O
by	O
the	O
Sigma	O
Corporation	O
,	O
equipped	O
with	O
a	O
Hyper	O
Sonic	O
Motor	O
(	O
abbreviated	O
HSM	O
,	O
Sigma	O
's	O
trade	O
name	O
for	O
photo	O
lens	O
focusing	O
technology	O
using	O
ultrasonic	O
motor	O
)	O
.	O
</s>
<s>
The	O
lens	O
was	O
produced	O
in	O
Canon	B-Application
EF	I-Application
mount	I-Application
,	O
Four	B-Architecture
Thirds	I-Architecture
System	I-Architecture
,	O
Nikon	B-Architecture
F-mount	I-Architecture
,	O
Pentax	B-Algorithm
K	I-Algorithm
mount	I-Algorithm
,	O
the	O
SA	B-Algorithm
mount	I-Algorithm
,	O
and	O
the	O
Sony/Minolta	B-Application
AF	I-Application
Mount	I-Application
varieties	O
,	O
all	O
of	O
the	O
same	O
optical	O
formula	O
.	O
</s>
<s>
Its	O
large	O
aperture	B-General_Concept
allows	O
for	O
a	O
shallow	O
depth	O
of	O
field	O
,	O
allowing	O
good	O
isolation	O
of	O
close	O
subjects	O
.	O
</s>
<s>
On	O
APS-C	B-Algorithm
sensor	O
cameras	O
,	O
its	O
field	O
of	O
view	O
equivalent	O
to	O
that	O
of	O
a	O
46mm	O
lens	O
(	O
Nikon	O
DX	O
,	O
Pentax	O
,	O
Sony	O
,	O
current	O
Sigma	O
bodies	O
)	O
,	O
48mm	O
lens	O
(	O
Canon	O
)	O
,	O
51mm	O
lens	O
(	O
older	O
Sigma	O
bodies	O
)	O
or	O
60mm	O
lens	O
(	O
Four	B-Architecture
Thirds	I-Architecture
)	O
.	O
</s>
<s>
On	O
the	O
Four-Thirds	B-Architecture
mount	O
,	O
it	O
is	O
the	O
only	O
affordable	O
normal	O
,	O
large	O
aperture	B-General_Concept
lens	O
,	O
therefore	O
it	O
is	O
popular	O
lens	O
on	O
that	O
format	O
.	O
</s>
<s>
With	O
most	O
photographic	O
lenses	O
,	O
vignetting	O
is	O
drastically	O
reduced	O
by	O
stopping	O
down	O
the	O
aperture	B-General_Concept
by	O
about	O
1	O
f-stop	O
.	O
</s>
<s>
This	O
lens	O
has	O
a	O
more	O
linear	O
response	O
to	O
stopping	O
down	O
the	O
aperture	B-General_Concept
.	O
</s>
<s>
To	O
reduce	O
vignetting	O
by	O
about	O
one	O
half	O
,	O
it	O
is	O
required	O
to	O
stop	O
down	O
the	O
aperture	B-General_Concept
by	O
over	O
3	O
full	O
f-stops	O
.	O
</s>
