Petri? V6 - INFRA-RED PHOTOGRAPHY; PETRI FILTERS FILTER FACTOR; DIAPHRAGM ADJUSTMENT

INFRA-RED PHOTOGRAPHY
When t aki ng in fr a-r ed pic ture s,
reset t he focu si ng distance to
the r ed li ne indicated
by th e
ape
rtur e f 1.8 (or f 2) on the
Depth
of Field Scale.
PETRI FILTERS FILTER FACTOR
* Filters reduce the amount of light entering the
lens , and when using them it is therefore neces ·
sary to increase the exposure . This increase is
called the FILTER FACTOR. As shown in the
table below , when the Y2 filter is used , it is
necessary to adjust the sh utter speed from
1/ 500 second to 1/ 250 second , or f/8 to f/5.6.
* The " UV" filter does not have a filter factor
and an increase in exposure is not necessary .
This fil
ter therefore also serves a useful purpose
in protectin g the lens from dust and damage .
DIAPHRAGM AD J USTMENT
B lack & Whi te C olo ur
YI
1/2
stop
UV (S kylight)
n
one
Y2
I
/I
W4
1/2
stop
YA 3
2
/I
C4 l/z
/I
RI
2
C8
1
II
II
Cl 2
1' /3
1' /3
II
POO
II
85C
l/a
II
POI
2
II
ND X4
2
II
17