<s>
The	O
Canon	B-Algorithm
EF-S	I-Algorithm
lens	I-Algorithm
mount	I-Algorithm
is	O
a	O
derivative	O
of	O
the	O
EF	B-Application
lens	I-Application
mount	I-Application
created	O
for	O
a	O
subset	O
of	O
Canon	O
digital	B-Device
single-lens	I-Device
reflex	I-Device
cameras	I-Device
with	O
APS-C	B-Algorithm
sized	O
image	O
sensors	O
.	O
</s>
<s>
Cameras	O
with	O
the	O
EF-S	B-Algorithm
mount	I-Algorithm
are	O
backward	B-General_Concept
compatible	I-General_Concept
with	O
the	O
EF	B-Application
lenses	I-Application
and	O
,	O
as	O
such	O
,	O
have	O
a	O
flange	O
focal	O
distance	O
of	O
44.0mm	O
.	O
</s>
<s>
Such	O
cameras	O
,	O
however	O
,	O
have	O
more	O
clearance	O
,	O
allowing	O
lens	O
elements	O
to	O
be	O
closer	O
to	O
the	O
sensor	O
than	O
in	O
the	O
EF	B-Application
mount	I-Application
.	O
</s>
<s>
Only	O
Canon	O
cameras	O
released	O
after	O
2003	O
with	O
APS-C	B-Algorithm
sized	O
sensors	O
support	O
the	O
EF-S	B-Algorithm
mount	I-Algorithm
.	O
</s>
<s>
The	O
"	O
S	O
"	O
in	O
EF-S	B-Algorithm
has	O
variously	O
been	O
described	O
by	O
Canon	O
as	O
coming	O
from	O
either	O
"	O
Small	O
image	O
circle	O
"	O
(	O
the	O
lens	O
projects	O
a	O
smaller	O
image	O
circle	O
than	O
normal	O
EF	B-Application
lenses	I-Application
to	O
match	O
the	O
sensor	O
)	O
,	O
or	O
"	O
Short	B-Algorithm
back	I-Algorithm
focus	I-Algorithm
"	O
(	O
the	O
smaller	O
mirror	O
used	O
in	O
APS-C	B-Algorithm
cameras	O
also	O
allows	O
optical	O
elements	O
to	O
protrude	O
further	O
into	O
the	O
camera	O
body	O
,	O
reducing	O
the	O
minimum	O
distance	O
between	O
the	O
sensor	O
and	O
the	O
back	O
element	O
of	O
the	O
lens	O
)	O
.	O
</s>
<s>
The	O
combination	O
of	O
a	O
smaller	O
sensor	O
and	O
shorter	O
back	O
focal	B-Algorithm
length	I-Algorithm
distance	O
enhances	O
the	O
possibilities	O
for	O
wide	O
angle	O
and	O
very	O
wide	O
angle	O
lenses	O
.	O
</s>
<s>
Such	O
lenses	O
designed	O
for	O
the	O
EF-S	B-Algorithm
mount	I-Algorithm
can	O
be	O
made	O
smaller	O
,	O
lighter	O
(	O
containing	O
less	O
glass	O
)	O
,	O
faster	O
(	O
larger	O
aperture	B-General_Concept
)	O
and	O
less	O
expensive	O
.	O
</s>
<s>
Although	O
not	O
all	O
Canon	B-Algorithm
EF-S	I-Algorithm
lenses	O
use	O
this	O
short	O
back	O
focal	B-Algorithm
length	I-Algorithm
,	O
they	O
cannot	O
be	O
mounted	O
on	O
DSLRs	B-Device
with	O
sensors	O
larger	O
than	O
APS-C	B-Algorithm
.	O
</s>
<s>
However	O
,	O
some	O
lenses	O
produced	O
by	O
third-party	O
manufacturers	O
may	O
feature	O
the	O
standard	O
EF	B-Application
mount	I-Application
if	O
they	O
do	O
not	O
have	O
the	O
shorter	O
back	O
focal	B-Algorithm
length	I-Algorithm
but	O
only	O
have	O
a	O
small	O
image	O
circle	O
.	O
</s>
<s>
Such	O
lenses	O
will	O
give	O
noticeable	O
vignetting	O
or	O
unsharp	O
outer	O
areas	O
if	O
used	O
on	O
a	O
35mm	B-Algorithm
film	O
or	O
full	B-Algorithm
frame	I-Algorithm
sensor	I-Algorithm
cameras	O
.	O
</s>
<s>
The	O
cameras	O
that	O
can	O
use	O
the	O
EF-S	B-Algorithm
mount	I-Algorithm
are	O
:	O
</s>
<s>
By	O
design	O
,	O
it	O
is	O
physically	O
impossible	O
to	O
mount	O
EF-S	B-Algorithm
lenses	I-Algorithm
on	O
EF-only	O
cameras	O
.	O
</s>
<s>
This	O
is	O
because	O
the	O
increased	O
proximity	O
of	O
the	O
lens	O
to	O
the	O
sensor	O
means	O
that	O
on	O
full-frame	O
sensor	O
or	O
35mm	B-Algorithm
film	O
EF	B-Application
cameras	O
the	O
lens	O
itself	O
would	O
obstruct	O
the	O
mirror	O
's	O
movement	O
and	O
cause	O
damage	O
to	O
the	O
lens	O
and/or	O
camera	O
.	O
</s>
<s>
While	O
it	O
is	O
possible	O
to	O
modify	O
the	O
lens	O
such	O
that	O
the	O
physical	O
obstruction	O
is	O
removed	O
,	O
allowing	O
for	O
mounting	O
to	O
EF	B-Application
mount	I-Application
cameras	O
,	O
the	O
rear	O
of	O
the	O
lens	O
would	O
still	O
obstruct	O
the	O
mirror	O
.	O
</s>
<s>
An	O
EF-S	B-Algorithm
lens	I-Algorithm
alignment	O
mark	O
is	O
indicated	O
by	O
a	O
small	O
white	O
rectangle	O
,	O
whereas	O
the	O
EF	B-Application
employs	O
a	O
small	O
red	O
dot	O
.	O
</s>
<s>
EF-S	B-Algorithm
camera	O
bodies	O
have	O
both	O
EF-S	B-Algorithm
and	O
EF	B-Application
alignment	O
marks	O
,	O
while	O
EF	B-Application
bodies	O
have	O
only	O
EF	B-Application
marks	O
.	O
</s>
<s>
Some	O
have	O
reported	O
success	O
attaching	O
EF-S	B-Algorithm
lenses	I-Algorithm
to	O
full-frame	O
bodies	O
with	O
the	O
use	O
of	O
an	O
extension	O
tube	O
;	O
however	O
,	O
this	O
does	O
not	O
eliminate	O
the	O
vignetting	O
problem	O
,	O
and	O
also	O
removes	O
the	O
lens	O
's	O
ability	O
to	O
achieve	O
infinity	O
focus	O
.	O
</s>
<s>
Also	O
,	O
attachment	O
of	O
EF-S	B-Algorithm
lenses	I-Algorithm
on	O
EF	B-Application
bodies	O
can	O
often	O
be	O
accomplished	O
by	O
removing	O
the	O
small	O
plastic	O
ring	O
seen	O
in	O
the	O
photo	O
above	O
.	O
</s>
<s>
This	O
modification	O
comes	O
with	O
caveats	O
,	O
one	O
being	O
that	O
on	O
some	O
lenses	O
,	O
like	O
the	O
EF-S	B-Algorithm
10-22mm	O
,	O
at	O
the	O
10mm	O
setting	O
,	O
the	O
element	O
protrudes	O
too	O
far	O
back	O
toward	O
EF	B-Application
mount	I-Application
camera	O
bodies	O
.	O
</s>
<s>
The	O
10D	B-Algorithm
,	O
D60	B-Device
,	O
D30	B-Device
,	O
and	O
earlier	O
cameras	O
share	O
the	O
EF-only	O
mount	O
with	O
the	O
full	O
frame	O
EOS	O
camera	O
bodies	O
,	O
and	O
also	O
with	O
the	O
APS-H	O
size	O
EOS	O
camera	O
bodies	O
(	O
1D	O
series	O
prior	O
to	O
the	O
1D	O
X	O
)	O
,	O
despite	O
having	O
a	O
smaller	O
sensor	O
and	O
therefore	O
a	O
smaller	O
mirror	O
.	O
</s>
<s>
The	O
EF-S	B-Algorithm
lens	I-Algorithm
mount	O
is	O
a	O
relatively	O
new	O
offering	O
from	O
Canon	O
,	O
so	O
the	O
selection	O
of	O
available	O
lenses	O
is	O
limited	O
compared	O
to	O
the	O
full	O
EF	B-Application
range	O
,	O
but	O
it	O
is	O
backward	B-General_Concept
compatible	I-General_Concept
with	O
the	O
EF	B-Application
mount	I-Application
,	O
and	O
can	O
therefore	O
still	O
accept	O
all	O
EF	B-Application
lenses	I-Application
.	O
</s>
<s>
The	O
variety	O
of	O
EF-S	B-Algorithm
prime	O
lenses	O
is	O
very	O
limited	O
in	O
comparison	O
to	O
EF-S	B-Algorithm
zoom	O
lenses	O
,	O
with	O
three	O
primes	O
to	O
nine	O
zooms	O
.	O
</s>
<s>
EF-S	B-Algorithm
lenses	I-Algorithm
are	O
very	O
popular	O
due	O
to	O
their	O
lower	O
cost	O
and	O
zoom	O
lenses	O
are	O
preferred	O
by	O
amateur	O
photographers	O
.	O
</s>
<s>
no	O
EF-S	B-Algorithm
lens	I-Algorithm
has	O
been	O
produced	O
with	O
the	O
"	O
L	O
"	O
designation	O
or	O
with	O
diffractive	O
optics	O
,	O
and	O
only	O
three	O
EF-S	B-Algorithm
prime	O
lenses	O
have	O
been	O
produced	O
.	O
</s>
<s>
Focal	B-Algorithm
length	I-Algorithm
Equivalent	O
focal	O
length( ×	O
1.6	O
crop	O
factor	O
)	O
Maximum	B-General_Concept
Aperture	I-General_Concept
range	I-General_Concept
Mark	O
Introduced	O
Macro	O
USM	O
STM	O
IS	O
10	B-Algorithm
–	I-Algorithm
18mm	I-Algorithm
16	O
–	O
28.8	O
mm	O
4.5	O
–	O
5.6	O
IS	O
STM	O
2014	O
10	B-Algorithm
–	I-Algorithm
22mm	I-Algorithm
16	O
–	O
35.2	O
mm	O
3.5	O
–	O
4.5	O
USM	O
2004	O
15	B-Algorithm
–	I-Algorithm
85mm	I-Algorithm
24	O
–	O
136	O
mm	O
3.5	O
–	O
5.6	O
IS	O
USM	O
2009	O
17	B-Algorithm
–	I-Algorithm
55mm	I-Algorithm
27.2	O
–	O
88	O
mm	O
2.8	O
IS	O
USM	O
2006	O
17	B-Algorithm
–	I-Algorithm
85mm	I-Algorithm
27.2	O
–	O
136	O
mm	O
4	O
–	O
5.6	O
IS	O
USM	O
2004	O
18	B-Algorithm
–	I-Algorithm
55mm	I-Algorithm
28.8	O
–	O
88	O
mm	O
3.5	O
–	O
5.6	O
I	O
2003	O
I	O
(	O
Jpn	O
.	O
)	O
</s>
