User manual

STOP OPENINGS
STOP openings regul ate the amo unt of li ght
passing through th e lens. Th ese openings are
enlarged or redu ced by moving th e lever C.
Lever C moves pointer D, see page 7.
A knowledge of the comparat iv e va lu es
of th e stop openings is necessary f or correct ly
timing expos ur es.
The stop openings are marked ]13 ·S , 4,
S .6 ,8, I I, 16 , a nd 22.
The largest stop opening is ]/3' S, This
opening allows a ppro x im ate ly thirt y pel"
cent mor e light to enter th an] /4, and about
two and a half times more than] / s.6 . Fr om
] /4 to ] / 22 each smaller opening (larger
number ) ad mit s half the li g ht of the pre-
ceding larger stop opening. Thu s, if the
correct expos ur e is 1/ 100 seco nd at ]/S.6,
then
th e expos ur e for ]13 .S should be I/2S0
seco nd; for] /8, I/ sosecond; for i / II, I/ 2S
seco nd; for ]h6, 1/ 10 seco nd ; a nd for ] /22,
I/S second.
The exposure for the average outdoor
subject, when th e s un is shining, i s] /S.6 a nd
1/ 100 second when using Kod ak Veric hr ome
Film. If the day is exceptionally brilliant,
u se the next sma ller stop to ] /5.6, t hat i s,
] /8 a nd 1/ 100 second. Th e important thing to
remember is the average exposure 0] ] / 5.6 and
[ / £00 second. Wh en th e light conditions differ
from the average, change the
ape rtur e,
20