<s>
BNCR	O
is	O
a	O
lens	B-Algorithm
mount	I-Algorithm
developed	O
by	O
Mitchell	O
for	O
use	O
with	O
its	O
reflex	O
35	O
mm	O
movie	B-Application
cameras	I-Application
(	O
long	O
back-focus	O
;	O
Bausch	O
&	O
Lomb	O
Super	O
Baltars	O
and	O
equivalents	O
)	O
.	O
</s>
<s>
The	O
lens	B-Algorithm
mount	I-Algorithm
is	O
not	O
identical	O
across	O
all	O
variants	O
,	O
thus	O
there	O
is	O
a	O
marked	O
difference	O
between	O
a	O
BNC	O
and	O
BNCR	B-Algorithm
mount	I-Algorithm
,	O
for	O
instance	O
.	O
</s>
<s>
This	O
notch	O
is	O
used	O
to	O
align	O
the	O
mount	O
to	O
a	O
locating	O
pin	O
located	O
approximately	O
45	O
degrees	O
clockwise	O
from	O
the	O
top	O
of	O
the	O
camera	O
's	O
lens	B-Algorithm
mount	I-Algorithm
.	O
</s>
<s>
The	O
quality	O
of	O
this	O
design	O
has	O
been	O
a	O
key	O
influence	O
in	O
the	O
design	O
of	O
the	O
Arri	O
PL	O
and	O
Panavision	O
PV	O
mounts	O
,	O
both	O
of	O
which	O
are	O
the	O
main	O
film	B-Application
camera	I-Application
mounts	O
in	O
use	O
today	O
,	O
and	O
both	O
of	O
which	O
have	O
four-pronged	O
flanges	O
oriented	O
based	O
on	O
locating	O
pin-notch	O
combinations	O
.	O
</s>
<s>
The	O
Arri	O
PL	O
mount	O
in	O
particular	O
is	O
very	O
similar	O
in	O
appearance	O
to	O
the	O
BNCR	B-Algorithm
mount	I-Algorithm
,	O
the	O
only	O
immediately	O
apparent	O
difference	O
being	O
the	O
ability	O
to	O
seat	O
any	O
of	O
the	O
four	O
notched	O
prongs	O
against	O
the	O
locating	O
pin	O
;	O
the	O
flange	O
focal	O
distance	O
and	O
diameter	O
also	O
differ	O
.	O
</s>
