Gossen MetraWatt lunasix - Page 20

Eight
combinotions
of which
you
moy r"eolly
use only
one! Now,
which combinotion might
be
"the
best"?
The LUNASIX
hos done its
best by
giving you
os mony equivoleni
poirs
so
thot
you
moy
select
o reolly
suitoble
one. After oll,
o
properly
exposed
picture
must
olso
be in shorp focus
-
which meons ihot
you
hove
to
ignore
some operture
(f-stop)
settings
ond
some
shutter
speeds.
Motion
colls for
o
short
exposure
to
prevent
o blurred imoge.
(Your
comero
instruction
book
or ony
good photogrophic
monuol
will
give you
informotion
obouf
"slowest
permis-
sible shutter speeds" for moving
obiects.) Needless
to soy, sports
pictures
demond the
shortest
exposures
(l/zsolol/rooosec.)
ond normol
motion
con be stopped
with
medium
speeds
(t/co
to
l/zso)
while,
for
still scenes, the slower
speeds
(1/ro
io
1/+
sec.)
ore odequote.
Of course,
for the
slow speeds,
you'll
need
o
good
tripod
or other comero
support to ovoid lock
of
shorpness
due to comero
shoke.
Depth
of
Field.
Since, usuolly,
you
will wont io
hove
neor
ond
distont obiects
equolly shorp
in
your piclures,
you'll
hove to
"close
down" the
lens. How
much?
The depth-of-field
scole
of
your
lens, or o seporote
depth-of-field
toble,
will tell
you.
A smoller lens
opening
gives
you
the desired
greoter
depth
bui-
it
colls for
o longer
exposure.
The conflicting
demonds of motion
ond
depth
of
field
reduce
the
choice
of f-stops
ond
shutter
speeds to such
on extent thot,
generolly,
only
o
few
possible
choices
remoin. Let's
soy
you
need
o shutter
speed
of of leost
1/eo
s€c. to stop motion
in
o
scene ond, to
get
odequote
depth of field,
you
need
o lens
opening
of f/5.6
or
smoller.
With the exposure
reoding
shown
obove,
you
would only hove
the choice
between
using f/8
with
t/oo
sec., or
f/5.6
wiih
t/rzs
s€c.
l5